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Modern Masonry: Natural Stone and Clay Products (1956)

Chapter:III. Research and New Technical Developments

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Suggested Citation:"III. Research and New Technical Developments." National Research Council. 1956. Modern Masonry: Natural Stone and Clay Products. Washington, DC: The National Academies Press. doi: 10.17226/9551.
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Suggested Citation:"III. Research and New Technical Developments." National Research Council. 1956. Modern Masonry: Natural Stone and Clay Products. Washington, DC: The National Academies Press. doi: 10.17226/9551.
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Suggested Citation:"III. Research and New Technical Developments." National Research Council. 1956. Modern Masonry: Natural Stone and Clay Products. Washington, DC: The National Academies Press. doi: 10.17226/9551.
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Suggested Citation:"III. Research and New Technical Developments." National Research Council. 1956. Modern Masonry: Natural Stone and Clay Products. Washington, DC: The National Academies Press. doi: 10.17226/9551.
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Suggested Citation:"III. Research and New Technical Developments." National Research Council. 1956. Modern Masonry: Natural Stone and Clay Products. Washington, DC: The National Academies Press. doi: 10.17226/9551.
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Suggested Citation:"III. Research and New Technical Developments." National Research Council. 1956. Modern Masonry: Natural Stone and Clay Products. Washington, DC: The National Academies Press. doi: 10.17226/9551.
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Suggested Citation:"III. Research and New Technical Developments." National Research Council. 1956. Modern Masonry: Natural Stone and Clay Products. Washington, DC: The National Academies Press. doi: 10.17226/9551.
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Suggested Citation:"III. Research and New Technical Developments." National Research Council. 1956. Modern Masonry: Natural Stone and Clay Products. Washington, DC: The National Academies Press. doi: 10.17226/9551.
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Suggested Citation:"III. Research and New Technical Developments." National Research Council. 1956. Modern Masonry: Natural Stone and Clay Products. Washington, DC: The National Academies Press. doi: 10.17226/9551.
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Suggested Citation:"III. Research and New Technical Developments." National Research Council. 1956. Modern Masonry: Natural Stone and Clay Products. Washington, DC: The National Academies Press. doi: 10.17226/9551.
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Suggested Citation:"III. Research and New Technical Developments." National Research Council. 1956. Modern Masonry: Natural Stone and Clay Products. Washington, DC: The National Academies Press. doi: 10.17226/9551.
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Suggested Citation:"III. Research and New Technical Developments." National Research Council. 1956. Modern Masonry: Natural Stone and Clay Products. Washington, DC: The National Academies Press. doi: 10.17226/9551.
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Suggested Citation:"III. Research and New Technical Developments." National Research Council. 1956. Modern Masonry: Natural Stone and Clay Products. Washington, DC: The National Academies Press. doi: 10.17226/9551.
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Suggested Citation:"III. Research and New Technical Developments." National Research Council. 1956. Modern Masonry: Natural Stone and Clay Products. Washington, DC: The National Academies Press. doi: 10.17226/9551.
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Suggested Citation:"III. Research and New Technical Developments." National Research Council. 1956. Modern Masonry: Natural Stone and Clay Products. Washington, DC: The National Academies Press. doi: 10.17226/9551.
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Suggested Citation:"III. Research and New Technical Developments." National Research Council. 1956. Modern Masonry: Natural Stone and Clay Products. Washington, DC: The National Academies Press. doi: 10.17226/9551.
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Suggested Citation:"III. Research and New Technical Developments." National Research Council. 1956. Modern Masonry: Natural Stone and Clay Products. Washington, DC: The National Academies Press. doi: 10.17226/9551.
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Suggested Citation:"III. Research and New Technical Developments." National Research Council. 1956. Modern Masonry: Natural Stone and Clay Products. Washington, DC: The National Academies Press. doi: 10.17226/9551.
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Suggested Citation:"III. Research and New Technical Developments." National Research Council. 1956. Modern Masonry: Natural Stone and Clay Products. Washington, DC: The National Academies Press. doi: 10.17226/9551.
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Suggested Citation:"III. Research and New Technical Developments." National Research Council. 1956. Modern Masonry: Natural Stone and Clay Products. Washington, DC: The National Academies Press. doi: 10.17226/9551.
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Suggested Citation:"III. Research and New Technical Developments." National Research Council. 1956. Modern Masonry: Natural Stone and Clay Products. Washington, DC: The National Academies Press. doi: 10.17226/9551.
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Suggested Citation:"III. Research and New Technical Developments." National Research Council. 1956. Modern Masonry: Natural Stone and Clay Products. Washington, DC: The National Academies Press. doi: 10.17226/9551.
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Suggested Citation:"III. Research and New Technical Developments." National Research Council. 1956. Modern Masonry: Natural Stone and Clay Products. Washington, DC: The National Academies Press. doi: 10.17226/9551.
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Suggested Citation:"III. Research and New Technical Developments." National Research Council. 1956. Modern Masonry: Natural Stone and Clay Products. Washington, DC: The National Academies Press. doi: 10.17226/9551.
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Suggested Citation:"III. Research and New Technical Developments." National Research Council. 1956. Modern Masonry: Natural Stone and Clay Products. Washington, DC: The National Academies Press. doi: 10.17226/9551.
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Suggested Citation:"III. Research and New Technical Developments." National Research Council. 1956. Modern Masonry: Natural Stone and Clay Products. Washington, DC: The National Academies Press. doi: 10.17226/9551.
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Suggested Citation:"III. Research and New Technical Developments." National Research Council. 1956. Modern Masonry: Natural Stone and Clay Products. Washington, DC: The National Academies Press. doi: 10.17226/9551.
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Suggested Citation:"III. Research and New Technical Developments." National Research Council. 1956. Modern Masonry: Natural Stone and Clay Products. Washington, DC: The National Academies Press. doi: 10.17226/9551.
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Suggested Citation:"III. Research and New Technical Developments." National Research Council. 1956. Modern Masonry: Natural Stone and Clay Products. Washington, DC: The National Academies Press. doi: 10.17226/9551.
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Suggested Citation:"III. Research and New Technical Developments." National Research Council. 1956. Modern Masonry: Natural Stone and Clay Products. Washington, DC: The National Academies Press. doi: 10.17226/9551.
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Suggested Citation:"III. Research and New Technical Developments." National Research Council. 1956. Modern Masonry: Natural Stone and Clay Products. Washington, DC: The National Academies Press. doi: 10.17226/9551.
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Suggested Citation:"III. Research and New Technical Developments." National Research Council. 1956. Modern Masonry: Natural Stone and Clay Products. Washington, DC: The National Academies Press. doi: 10.17226/9551.
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Suggested Citation:"III. Research and New Technical Developments." National Research Council. 1956. Modern Masonry: Natural Stone and Clay Products. Washington, DC: The National Academies Press. doi: 10.17226/9551.
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Suggested Citation:"III. Research and New Technical Developments." National Research Council. 1956. Modern Masonry: Natural Stone and Clay Products. Washington, DC: The National Academies Press. doi: 10.17226/9551.
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Suggested Citation:"III. Research and New Technical Developments." National Research Council. 1956. Modern Masonry: Natural Stone and Clay Products. Washington, DC: The National Academies Press. doi: 10.17226/9551.
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Suggested Citation:"III. Research and New Technical Developments." National Research Council. 1956. Modern Masonry: Natural Stone and Clay Products. Washington, DC: The National Academies Press. doi: 10.17226/9551.
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Suggested Citation:"III. Research and New Technical Developments." National Research Council. 1956. Modern Masonry: Natural Stone and Clay Products. Washington, DC: The National Academies Press. doi: 10.17226/9551.
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Suggested Citation:"III. Research and New Technical Developments." National Research Council. 1956. Modern Masonry: Natural Stone and Clay Products. Washington, DC: The National Academies Press. doi: 10.17226/9551.
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Suggested Citation:"III. Research and New Technical Developments." National Research Council. 1956. Modern Masonry: Natural Stone and Clay Products. Washington, DC: The National Academies Press. doi: 10.17226/9551.
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Suggested Citation:"III. Research and New Technical Developments." National Research Council. 1956. Modern Masonry: Natural Stone and Clay Products. Washington, DC: The National Academies Press. doi: 10.17226/9551.
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Suggested Citation:"III. Research and New Technical Developments." National Research Council. 1956. Modern Masonry: Natural Stone and Clay Products. Washington, DC: The National Academies Press. doi: 10.17226/9551.
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Suggested Citation:"III. Research and New Technical Developments." National Research Council. 1956. Modern Masonry: Natural Stone and Clay Products. Washington, DC: The National Academies Press. doi: 10.17226/9551.
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Suggested Citation:"III. Research and New Technical Developments." National Research Council. 1956. Modern Masonry: Natural Stone and Clay Products. Washington, DC: The National Academies Press. doi: 10.17226/9551.
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Suggested Citation:"III. Research and New Technical Developments." National Research Council. 1956. Modern Masonry: Natural Stone and Clay Products. Washington, DC: The National Academies Press. doi: 10.17226/9551.
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PART THRE:E PRESIDING CHAIRNIA~- Howard T. Fisher Howard T. Fisher ~ Associates, Inc. Chicago, Ill. Research and New Technical Developments M R . C . E . S ~ ~ ~ ~ N G: Sometime during the confusion of ~ ~ a Harvard education that incluclec] being a teacher, ~ ~ acting as consultant to our Fecleral~ Government and the United Stations, 3 ~ research on land use. housing and integrated buil(ling design, 4 ~ practicing as an architect. 5) presiding over a music school board of trustees, and 6) associating with a variety of professional societies harboring consultants, architects, planners ant! others, your next session chairman found tinge to erect a personal cor- porate facade to cover his manifold activities. ~ ant sure you are all aware of his solid professional accomplishments as an architect and a planner. Ladies and gentTen~en, Mr. Howard T. Fisher, Howard T. Fisher & Asso- ciates, Tnc., Chicago. 51

Thermal Performance of Clay Masonry Walls R . F ~ s H E R: Mr. Walker this morning made one statement that interested me espe- cially and which T wrote down at the time. He said substantialZy as follows: "The joining of material is more important than the mate- riaZ itself." This is a statement of the very greatest importance in the construction indus- try, and not perhaps generaZZy recognized by all of the manufacturers o f materials and the _1 'r _ r _ ' 1 architects, engineers who are concerned with design. Our first speaker this afternoon is Clarence 17\1onk, manager of the Structural Clay Prod- ucts Research Foundation's Architectural and Engineering Research Division. He is IN recent years designers of air conditioning systems have come to realize that predictions of heat loads based on tile conventional cal- culations (using the "U" factor) gave higher C. B. Monk, Jr. Structural Clay Products Research Foundation. Geneva, III. particularZy concerned with this question of the joining of materials not only how these materials join, but how these materials join other materials-how walls meet roofs how f oors meet partitions, and so on. Mr. Monk was an architectural engineer with the Armour Research Foundation of the Illinois Institute of Technology, and has been an instructor in the civil engineering depart- n~ent of that school anal in the mechanical engineering department of the University of ZZinois. He is a member of the American So- ciety of Civil Engineers and the National Society of Professional Engineers. design requirements than the completed buiid- ings demanded. This experience plus both analytical and experimental findings have high- lighted the importance of the influence of 53

density and specific heat of building materials on the thermal transmission into and within structures. The usual way of making heat gain (or heat loss ~ calculations is to think of some fixer! outside temperature, perhaps 95° to lL05° F. The inside temperature is usually chosen from some control level, 70° to 80° F. The fixed temperature difference between the outside and inside temperature is the n~eas- ure of the amount of air conditioning ~ or heating) needed as calculated from the k or U factor. The fallacy in these assumptions is thinking in terns of a constant outside ten~- perature. The inside temperature nary be con- stant; we like to have it so. But since the sun rises anc! sets every 74 hours, there is inevitably a rise and fall of outside air ancT building sur- face temperatures. This cycle in heat gains (or losses) is affected to a n~arkec! extent by the mass characteristics of the builcTing materials (specific heat and density) as well as their thermal transmission coefficients. Recent field experience has shown that consideration of the thennal transmission coefficients alone is not a sufficient basis of calculation; specific heat and density are equally important. Specific heat is the measure of the amount of heat requirec] to raise a certain quantity of substance, we'll say; a pound, one degree of temperature. Certainly it takes snore heat to raise the temperature of one pound of water one degree than of one pound of alun~inun~. Archaeologists tell us that primitive Nan soon learned that the continued warmth sus- tained in the stone he heated to cook his food was ren~arkably effective in keeping hint warns over a perioc! of tinge after the fire cried out. In the modern age, the hot water bottle is familiar to all of us. This is a means of con- veying heat by means of specific heat an density. In climatology the influence of n~aritin~e bodies over continental lane] areas on te~- ~4 perature is well known. Cities near the Great Lakes area enjoy higEcr temperatures cluring the winter than cities in the central plains area at the same latitude. The reason is that the relatively higher specific heat of the water means that the water temperature never sinks to the same Tow level as the lancI masses. NVall constructions having high heat storage capacity; (i.e. high specific heat and density characteristics) will dampen the effect of the ~naxin~um rate of heat gain (or Toss). As soon as the ~naxin~un~ outside surface wall tem- perature is reached. the surface begins to cool. As tile outside wall continues to cool, the heat flow that 1las started on its way through the wall at the time the maximum surface tem- perature was reached will be split into a quan- tit~; that will flow out as well as in. This cia~npens the amount of heat finally reaching tile inside surface. The greater the heat stor- age capacity the sneakier will be the instantane- ous rate of heat flow to the interior. Obviously this reduces the capacity size require(1 of the cooling equipment. What floes this mean to Duncan comfort? The (la~npening effect of wall mass wit] reduce the fluctuations of inside wall temperatures. People living in frame houses frequently ex- perience the necessity of setting the thern~o- stat higher to compensate for a rapidly noosing coIc! front which suddenly engulfs the house. This sense of chilling is due to a sudden fluctuation in insicle wall temperatures. In~- ~nediatel~, radiant heat is lost front the Duncan boils; to the wall. Another matter that is of importance is that mass contributes to a lag in time of the heat progressing through the wall. For example, this Slav amount to six or eight hours for a relatively heavy masonry wall, before the heat which has accumulated during the day begins to reach the interior later in the evening. But in the n~eantin~e the external temperatures hex e cTroppecT deciclecITy ancT you can then avail

yourself of nocturnal cooling by an attic fan. Allis leas been a great benefit in Australia. Their people have e~nployecl this n~etho<1 to the fullest extent, almost eliminating tl~e need for air conditioning systems in low-cost blousing in that particular part of the globe. In sugary, theory and experimental facts to ciate show evidence that high heat storage influences tI~ennal flow in the following ways. T. Reduces the instantaneous rate of lariat gain or loss. The initial size of the air condition- ing or heating equipment may be reduced by; as much as 25-50%. 7. Dampens variation of inside surface ten~- peratures, thus contributing to greater co~n- fort to the incliviclual clue to racliant ex- cI~ange between Lois and his environment. 3. Delays the peak lint Toad reaching the in- terior (time lag) which allows the use of nocturnal cooling by attic fan for uncondi- tionecT space or of favorable electrical rates on air conditioners for conditionecT space. T~_ HEORETICAL L)ISCUSSION Tl~e factors that contribute to the ~nagni- tude ancT variation of surface wall temperatures are complex. Direct solar radiation plus rac:lia- tion frown the atmosphere anc! terrestrial ob- jects are tl~e initial sources of heat. The amount of this latest that goes into the outside wall surface is a function of the reflective characteristics of the surface. Wl~ite or buff surfaces may reflect 40-60~7o of energy received, Wylie dark colors may absorb as much as 90~ and reflect only ~0~. (The building surfaces the~seIves are sending out radiant energy to their total environment to further con~plicate the excl~ange.: As a builcTing is surrounded by air, tem- perature variation in the passing air masses plus the speed of air movement affect the con- vective transfer of heat into a building wail surface. Surface texture characteristics influ- er~ce this phenomenon. The contained effects of solar radiation, air temperature, and air velocity is frequently rep- resented by the "Sol-Air Temperature" which is the equivalent temperature at the weather surface of the wall to give the saline heat flow that actually takes place on to the surface due to the above causes. It is similar to (but by ~nathe~natical definition not exactly) the ten~- peratures of the outside wall surface. Outside air temperatures may hare daily variations ranging front ~ 7 to ~ ~ clegrees on the east coast to 33 to 47 degrees in the Rocky Moun- tain area. It is important to note that the air temperature selclo~n exceecis a n~axin~u~n of 100 to TI0°F. whereas the Sol-Air ten~pera- ture may have peaks ranging front ~ 30 to ~ 60 ° F clepending on the wall surface. Tl~e daily variation in Sol-Air temperature may be 70°F on a north wall to /0°F for a west wall. The flow of such a periodic heat cycle as cTescribecl above through a builcTing wall is ciepenclent on the physical parameter: Thermal cliflusivitv (`x) a k , PA Adhere k coefficient of thermal transmis slon p density C specific heat It is this physical property that is of signifi- cance in discussing periodic heat flow as op- posecl to k or U for steacly heat transfer. Un- fortunately ~nathe~natical expressions relating this property to heat flow are not in a form suitable for office computation. However the 1950 edition of tile ASHAE Guicle approxi- n~atec] the exact solution as follows: q U ~ t,~-ti ~ + ~ U ~ te-tm ~ Revere q snag. rate of instantaneous heat gain where to= average Sol-Air temperature te= Sol-Air temperature at a tinge earlier by an amount equal to the time lag 55

ti average inside air temperature g- a factor that ciepencis on the wall thick- ness and orientation. The tinge lag is the delay in the heat gain clue to mass in passing through the wall. For 8" of brick this is theoretically 5.5 hours; for 2" of wood T.3 hours. The two wails have about the sense U factor, yet the theoretical n~axin~um rate of heat gain is 60: greater through the wood for a west wall. The n~axi- ~nun~ heat gain would occur around 6:00 P.M. for the wooc! and 10:00 P.M. for the brick. Exact theoretical solutions taking into ac- count mass effects have been achieved analyti- cally by thermal circuit analysis or experi- ~nentally by electrical or hydraulic analogies. These methods depend on the ~nathen~atical parallel between electrical or fluid flow and heat flow. These exact solutions substantiate the above approximation and emphasize the influence of the heat storage of interior walls in re(lucing peak loacis. ExPER~ExT~ DEs~oN To determine with precision the influence of heat storage on tile thennal performance of cIav ~nasonrv the Structural CIav Products Research Foundation undertook tile experi- ~nental stucly of eight wall constructions: 6 clay n~asonrv;, ~ wood frame, and ~ natal pane! (See Figure ~ for details). The technique of the experiment employed cubical huts (10' :; 10' in plan). Taxis pern~itted erecting 8' 2: 8' HEAT FLOW THROUGH MASONRY 1 500 1 400 10" CAVITY WALL /__ 8" TILE WALL \ \ 6" TILE WALL \ 8" B R IC K WALL '\ 'A- 1 300 , ~ f RAME WALL _ BRICK VENEER _ TRAILER _ METAL PANEL f 6" BRICK WALL FIGURE 1 Plot plan of test site showing ar- ran~,ements of thermal huts. 56 panels in each wall of the but. oriented to the four points of tile compass. Tile purpose of adopting an experimental study on such a relatively large phonological scale was to obtain representati~eness hotly as to flee panel construction and ~orI;n~ansl~ip ancT as to tl~e statistical influences of weather patterns. Smaller specimens were held not to yield this effect. Prior to e~nbarI;ing on flee program it was obvious that much fine theo- retical work had been cone in the field of periodic latest flow. However. for clay masonry, the projection of this theoretical work into practical results depen(led entirely on i(lealizecl mathematical assumptions and on existing laboratory cleter~nination of physical prop- crties. It was felt that the combine(1 influence of all variables subject to periodic weather patterns could best be studiecl by full scale huts. However elaborate the theory, it is no better than tl~e experin~ental ~ ork on which it is based. The use of thermal huts for experimental treat flow studies has been employed by several Con~nonwealth Experin~ental Stations. Scan- dinavian researchers have built then. In this country vapor transmission studies at Penn State and thermal circuit investigations at UCLA are letdown to have used thermal huts. The n~etho(ls of constructing the huts are shown in Figure 7. Each hut rests on a rein- forcecl concrete slalom. The walls are separated front each other at the corners by plywoo(1 colun~ns filled with insulation. The walls were erected on a 12" bed of rigid insulation (k- .34~. The floors are covered with rigid insula- tion board (K=.25) to a depth of 9". The ceilings are insulated with 10" of loose fill in- sulation covered by reflective insulation. The attic space is vented and the roof surfaces are painted alun~inun~. The construction is de- signed to force the heat floss primarily through the wall panels. Figure 3 show-e how access' after the soZid waZZ panels are in place, is pro

FIGURE 2-View of huts prior to installation of wall panels. viclecT to the inside through~a trap door in the roof. Instrumentation includes thermocouples in each wall (16 in eacl, face plus several ac~cii- or navies T°F ~ record of the inside ambient air temperature is continuously, obtained. The instrument sI~eiter contains watt hour meters that measure total power consumption by each lout and flow meters that measure the total flow of water through the air conditioner. Thennopiles measure the temperature gra- ~lient in the air conditioning water. It is ap- parent frown this instrumentation that the total heat flow into the huts may be checlce against the heat re~nove(l. This has been done and found to balance within 3 to 66,7G. NVeather data obtained inclu(le outside ambient air temperature, wind speed, wind direction, amount of precipitation, and solar radiation. Provision exists to measure air con- ditioning condensate (latent heat ~ and hu- ~nidit~; inside each hut. An over-all view of the test installation is shown in Figure 5. i. ~ ~..~..~.~ ~ ~ . .... . ~ FIGURE 4 Instrument shelter housing 144 point longer. FIGURE 3 Typical hut with access trap door open. tional ones of interest within the wall). Three heat flow meters are placed on the inside of each wall (ancT eventually on the outside). Data front these instruments are recorclect (see Figure 4 ~ in an instrument shelter which houses a I14 point logger. The tc~nperature within the huts is ~nain- tained constant with the aid of 3 kw electric heating cements and a sneaks 3~4 ton air con- ditioner. A spiral type ther~noregulator ~nain- tains temperature in the huts to within plus ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ . ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ .~ ~ ~ ~ ~ . ~ ~ ~ i. ~ ~ ~ ~.~.~ ~ ~ ~ ~ . ~ it. it. FIGURE 5-Complete test installation. 57

TES T RESULTS Since tile test project started in Sentencer of 1955, only ciata for the winter season are now available. The influence of heat capacity during the winter season has not been studiecl bv theoretical analysts for it has been assurnecl J J that the range of ciaily temperature variation was greater in the sundrier than in the winter. the incident solar racliation is greater in sun~- ~ner than in winter, and the difference be- tween insicle and outside mean temperatures is n~uch greater in the winter than the sum- mer tending to mask the influence of tee ciaiTy tenaperature range. Due to these consiclera Building Ail Brick Veneer (a Building #2 10" Cavity (c ) Building #3 S" Solid (b) Building #4 "SCRbrick'(b) :3rlilding #> 8" Tile (c) Building #6 6" Tile (c) Building #7 Steel Panel (a) Building #8 Wood Frame ~ a Ma';. Teacup. °F Min. Teacup. °F Average Wind Nic1. % Possible Sun Precipitation Trace tions the conv~ntior~al steady flow Sterna properties were felt adequate for heating sea- son calculations. Data presented below sug- gest a re-exan~ination of this viewpoint. Table ~ su~nn~arizes the experimentally ob- tainec] Us factors cletern~ined uncler periodic tl~er~nal flow clue to varying weather patterns. This factor represents tile average heat Toss through the walls of the thermal hut for the period of stucly per clegree F temperature dif- ference between average inside ancT outside ambient air (see Table If. Four three-day periods have been chosen as typical results for n~icT-winter ancT earls; spring. TABLE I UV VALUES OBTAINED FROM THERMAL HUT PROGRAM Jan. 10-13 Feb. 3-6 Us i\/Iar. 9-17 A,br. 77-30 .10! .320 .936 9 .47, .507 .767 .092 .297 .421 .452 .339 .394 .189 .1'T 38 78, 15 MPH 6 MPH 0-0-100 100-99-76 NOne .117 .397 .491 .678 .186 .146 .408 .375 .42) .1,0 ( a ) NNiall constmction includes interior Lisle and insulation # ] (b) Interior finish and insulation added between Feb. / and Liar. S. #a. =4 (c) Exposed masonry on interior, - I. ~5. -'6 58 .094 .096 .347 .183 .117 .397 .704 .167 .17) .40& .431 .439 .750 .12) ~9 14 MPH 14 RIPE 100-70-68 7 5-0-0 7.38~, Rain .93/ 775 .150 .179 .110 78 36 .47 3

A variety; of weather patterl-;~s is represented. The period front Jan. 10-13 represents as near a steacly state as was obtained during the period of record: even here a 10°F range was experiencecI. Feb. 3-6 was a period of high temperature range, Tow wincT speecTs, ancT large percent possible sunshine; therefore, cyclic in- fluences shouicT be most pronounced cluring this period. Tile period April 27-30 inclucTecT mostly overcast skies witty consiclerable rain. The Us factors are those calculatecT front tee ASHAE Guide for steady state condition. The one exception is the natal pane} which value was obtained front the manufacturer who reporter! the results of laboratory tests on wall sections inclucTing through-the-war:! metal ties. The construction will not be clescribecl in detail leers, but suffice it to say blat tile clay masonry walls were all composed of red clay units, lightly texturecT. The wall finishes used consisted of conventional furring, blanket in- sulation, ancT ciry wall techniques. The woos] France but was coverer] with white ship-lap sicling. The metal panel was a typical in- Justrial type containing ~ ilk" of Fiberglas insulation with a metal sheet interior finish. Tl~e metal surface being galvanized was left unpainted; this surface has darkened with age. Generally speaking, there is a marked clif- ference between the Us ant] Uv values. The France and metal huts have Uv values above Us; the clay masonry buts have values below. While differences in color do have an effect, it should be noted that the frame was white and the metal was darkened galvanizecT, each representing racliation extremes on both sides of the reel brick color; yet both of these con- structions having sn~all mass showed heat Tosses greater uncler periodic heat flow than predicted front steady state knowledge (10- 20G/G for France and 30-6070 for metal). The clay n~asonr,v (lisplayed Us values that were 0-705 below tee Us values with a trend to smaller differences occurring with the hollow units and larger ctifl:erences with the solid units. A comparison between the brick veneer and France is of interest since these two construc- tions hac] nearly identical Us factors. Yet the veneer experienced heat Tosses roughIv lL0~7O less than caTculatecl, Whereas the France showed 15':0 snore. Maltese two constructions were near- ly iclentical except the outside covering being 4" of red brick in the one anc] I" of white wooc! siding in the other. The table below shows for tile Feb. 3-6 period the daily Us values for the north anc] south walls of the two huts. Us UN North NVall _/ ~ 2/4 2/5 . . . . . . . . . . . . . . . U>. Softly NVall 2/3 2/4 / ~. Brick Wood Veneer Fit ame .112 .110 .118 .135 .119 .148 .12S .131 .069 .096 .067 .11 3 .063 .089 Tllese data, typical of other perio(ls. show that even on tile north wall (where color dif- ferences are n~inin~ized) the veneer values are much less than the frame values. The low Us values of the soutl1 wall are due to the solar radiation received during the day. The data; also point out tile difficulty of choosing an arbitrary U factor to be representative of Motif orientation and periodic effects. Tllose designs based on U factors carried to tile third decimal place suggest an accuracy not warranted. A comparison between the "SCR brick" (a 6" througll-the-wall clay unit) and the metal louts is worth noting. Tl~e insulated values of these walls are roughly the same (.175 and . 150, respectively) . The Uv for the "SCR brick" is on the average 157 under tile Us value whereas flee Uv for the metal is about 507 above. On this basis. if the two waZZs had 59

identical U factors, 55C:o more heat would be lost through the metal pane, than the "SCR brick." Presumably these differences are due to mass. The experimental determination of Us for the metal panel is reported to have taken into account through-the-wall ties. The darkened thetas surface should have had the advantage in receiving solar radiation to re- cluce treat loss. Thought not studied in as n~ucl~ detail as the U factors above, the maxin~un~ rates of heat loss shown for the brick veneer and frame during the Feb. 3-6 period are: Brick Veneer Wood Frame btu/ fir. btu/ hr. North Wall 2/3 2/4 2/5 South Wall 2/3 . . . 274 . ... ... 2/5 60 500 450 400 400 350 300 600 500 350 600 500 350 Thus tile demands on the capacity of tile heating source were 20WG less in the case of the brick veneer. SUMMARY The results obtained thus far in talc Floral hut program were primarily for the winter season. Contrary to orthodox assumption, periodic heat flow was shown to have a signifi- cant influence on heat losses. Under the periodic heat flow of actual winter weather patterns wall constructions having low mass, such as France and metal panels, were shown to have total heat Tosses significantly greater than front steady state calculations (ranging front 10-20~7o for the France and front 30-40% for the metal). For walls having high mass. such as clay masonry, the total heat losses were less than front a steady state calculation (rang- ing front 0-20~7O ~ . The precise extent to which mass (both density ant] specific heat) affect this result may await future detailed stucly of all the physical parameters concerned.

Ceramic Veneer Panelizing M R . F ~ s HE R: One of the fine things about these BuiZ6ing Research Institute Con- ferences of this kind is that a wide variety of viewpoints is re,~resented. In contrast to the viewpoint of Err. Monk for the engineers, we have an industriaZ viewpoint expressed by Mr. Barnes who wiZZ speak on ceramic Veneer pane7lizing. EVERY alert November of the buiTcling industry has, ~ awn sure, noted with great interest the trend in recent months toward the extensive use of curtain wall construction. It has become so well known and so widely used that no definition at this time is requirecl. Mender manufacturers of the Architectural Terra Cotta Institute have noted this trend and recognize the obvious merits of curtain wall construction. Albert E. Barnes Cladding, McBean & Company San Francisco, Calif. In ad`lition to his 29-year connection with GZadding, McBean ~ Company as manager of architectural products promotion, Albert E. Barnes is also Secretary of the Architectural Terra Cotta Institute, a past president of the Southern California Chapter of the Producers Council, and a member of the Construction Specifications Institute. As has so often been pointed out, curtain wall design elin~inates the need of a back-up wall, thereby reducing the required wall thick- ness and reducing the weight of the exterior wall. As a matter of fact, there has been a trencT toward thinner mason curtain walls for a number of years and some of the largest and finest recent buildings on the Pacific Coast have had exterior masonry non-Toad bearing walls of S" thickness rather than the 61

thickness of 12", 17" or 19" so often referred to in comparisons of thinner curtain wall con- struction. This reflects a saving, both as to installation time involved and as to cost. The obvious objective of curtain wall construction is the ultimate reduction of thickness anc! of n-the-wall cost. Ceramic veneer manufacturers have, for several years. cTiscussecT this problem ancT actual research and procLuction of test panels has been in progress for snore than two years. ceran~ic veneer panelizing, as it is known to- ciay, is the development of ~ precast ceramic veneer curtain wall panel which is cast and cured under icleal stop conditions and then cleliverec3 to the job and attached in place on tee building by bolted or welder! connections. Emenders of the ATCI have adopted the tracle- mark name 'CV PANEEWALL," The Prefabri- cated Ceramic Veneer Curtainwall. This cle- velopn~ent is most significant in that for the first time in the buiT(ling industry, the time proven advantages of high-fired glazed ~nason- ry facing material are now oracle available for curtain wall construction. Our discussion today will include two gen- eralL types of panels which are known as CV PANEEWALL. We will refer to the first as a curtain wall panel, which is fabricated with liglltweight aggregate concrete backing, is ap- proxi~nately 3" to 5" in thickness clepending upon fire resistance requirements, and is avail- able in units up to approximately 30 sq. ft. This pane] was clesigned for ant! is now in- stallecT on the Methodist Hospital in Arcadia, California. In fact, it is because of an urgent request by the architects, Neptune and Thomas of Pasadena, for a method of using ceramic veneer in curtain wall construction that we acceleratec! our activities in develop- ing this panel. We are indebted to then for their continued interest and cooperation (lur- ing the design and fabrication of our curtain wall panel for this project which is now being constructed by the Ford l. Twaits Co. of Los Angeles. We have also developed a thinner, lighter weight panel, approximate; TI/2" to 13/4'/ in thickness which is clesigned for use in window wall construction. ~. = ~ ..... PRECAST CERAMIC VENEER SPANDREL PANEL DEVELOPMENT OF CV PANEEWALL The development of ceramic veneer panels involvecl the adaptation of well known and thoroughly proven techniques of lightweight precast masonry construction. Tile problem consiste(1 of developing a satisfactory tech- nique for placing ceramic veneer ~ arcllitec- -tural terra cotta) facing units in a form ancl casting a reinforced lightweight concrete back- up that would produce a panel of required thickness and strength in order to handle the panel cluring the curing, delivery and erection and to provide the proper resistance to wincI pressure and seismic forces when the panel is installed in the structure; also, to provide a panel that is impervious and that will remain so cluring the life of the structure. In this re- spect, attention is calle(l to the proven char- acteristics of good masonry construction as to permanent water resistant qualities and low maintenance cost. The ceramic veneer facing unit is approxi- n~ately I" thick and is a cle-aired, extruded, precisely finished clay body with a high-fired impervious glazed finish. Tile lightweight ag- gregate used in the concrete back-up is an ex- pan(led shale type such as Basaiite, Rocklite, Hayclite, etc., and was chosen to obtain con- crete of lightest weight and greatest strength.

:.: ~ ::: : ::: ~ : ... . . ~ Hi t , Fit ~ :: ala:::::-:: ~::::: - :> :~: - - - - ~ - - ~ I' 1 .. ,,ii=i - - ~ - - ~ .. '.~:~. - - - = i?~) ~ ~-..s - - - - - - - - ~ -~-:::.-~ ~- - - - - ~ - ~ - - : - a = I ~ ~ _ · v. - - 1 · at.--~ :: ~ l _~ e _ - ~: - __ ~ ~. ~ ~ ~ ~ ~.~. ~. ~.~. ~. ~.~. ~.~. ~. METHODIST HOSPITAL. ARCADIA cAT.TT; Freer Rev ~1~`T~tin~ ~hn`~ri^~ i~ll~;~ Vermiculite concrete is added to the panel to provide the required fire resistance or adcli- tional insulation when specified. The reinforc- ing steel used is a heavy galvanized welded steed mesh or reinforcing bars or light cleanness may be used to provide the proper reinforcing. PHYSICAL PROPERTIES OF CV PANEEWALL After several years of research, it has been determined that a thickness of I" of ceramic veneer facing with a backing of 2" of rein- forced lightweight concrete. in which reinforc- ing steel Las been incorporated, provides tile required strength for this type of panel. Work is now proceeding on the development of a much thinner panel, approximately 3/". for use in window wall construction in which chan- ne] steel is incorporated in the reinforcing de- sign in order to furnish satisfactory; tensile strength requirements in the 3~4" thickness of concrete this thinner pane] is being developed 7 . ~ ~ ~ _~ ,, ~ An, ~- ~744~ ~ ^~ ~61~_F84 of 9'0~" panels and 4'6" panels. to lee used in aluminum or steel window wall construction. There is a permanent bond between the ceramic veneer facing and the concrete back- ing. This is assured by thoroughly dampening the CV units, applying a brushed-on bond coat of neat Portland cement and nearing sure that the low water-cement ratio concrete is effec- tively vibrated for n~axin~um density and bond. The fre resistance of the basic 3" panel is one and one half hours, according to recent tests at the Ohio State University Research Laboratory. However, a higher fire rating may be obtained, when required, by the addition of vermiculite concrete or other rated insulating n~aterial. Also. a precast CV n~uZlion has been developed and can be furnished where fire rat- ing requirements indicate the advantage of a masonry mullion. The excellent weather resistant qualities of ceramic veneer are assured by tile higll-fired 63

METHODIST HOSPITAL' ARCADIA' CALIF. Cement mortar bed is pre- pared and Koroseal gasket placed. impervious glazed finish. In casting the CV panel, joint strips I/2" deep are used which are later remove so that the finished panel can be pointed with a dense pointing mortar and tooled to provide proven water repellent quali- ties. Since the thermal coefficient of expansion of the CV PANEEWALL is considerably less than n~etal, ~ninin~un~ temperature n~oven~ent is assurer! and the n~ethods used in casting produce a monolithic watertight panel with no voicis in which condensation or other moisture can collect. Since there are no through-waZZ joints in the panel itself, the only seal required to prevent infiltration or rain penetration is around the perimeter of the panel where it adjoins a metal nonillion or other element of the building struc- ture. These joints are clesignecT of polyvinyl chIoricle plastic. Because of the ~nini~nu~n temperature ~noven~ent n~entionecT above, the adjusted compression against the polyvinyl gasket remains well within the n~odulus of elasticity of the material. This provides a per- ~nanent joint seal. As far as the thermal conductivity of the CV PANEEWALL is concerned, it is to be noted that in acicTition to the basic U factor of the masonry panel, depending upon the thickness and bacic-up material to be used, the pane] has the adcTitional benefit of heat lag, the recog 64 Toggle bolts placed through strap anchors into holes in mullions. Fiber gasket and metal shims placed for accurate adjust- ment. nized heat capacity of a masonry wall widen in- tern~ittent heat Toacls, such as the hot after- noon sun, are tile main consideration. A Tower U factor is easily obtainer! by additional in- sulation which may be applied to the panel at the time of casting or to the interior surface of the wall after installation. In the case of the Arcadia Hospital, on which this panel is now installed, a satisfactory U factor to meet rigic! air conditioning require- ~nents was obtained by a(lcling I" of vern~icu- lite plaster to the back of the spandrel wall after installation. This insulation covered the metal mullions as well as the masonry panel, thereby elin~inating any through-wall metal connection. Attention is called to the fact that masonry panels which have no through-wal1 metal surround have a more consistent insulat- ing value than any type of panel that involves a metal perimeter frame and through-wall metal connections. FABRICATION OF CV PANEEWALL No particular propylene or unforeseen dif- ficulty was encountered in casting the panels; the casting was accomplished by men well ex- perienced in precasting concrete units. in regard to anchoring connections on the panels for the Methodist Hospital, strap anchors were attached to the panel reinforcing

mesh and en~bedded in the concrete backing; these were shaped to project at the ends of the panels for attachment to the back of the aTun~i- nun~ Auctions. The panels were then set on the concrete floor slab in a cement mortar bed and were bolted to the back of the alu~ninu~ mullions by toggle bolts through the project- ing strap anchors. A fiber gasket was used for insulation between steel and alu~ninu~. Metal shines were also used to assure proper con~pres- sion of the polyvinyl gaskets against the alun~i- nun~ mullion angles. :Et is possible to enrobed anchor points in a lightweight concrete pane! to meet the re- quirenacuts of any anchoring system which the architect or engineer may design. Recently, we have developed details to show proper anchor- ing for a pane] set on the face of a building, supporter] be; anchor clips to a steel or concrete frame. For window wall construction, no clif- ficulty is foreseen in inserting a pane] of proper thickness into a surrounding metal France; taxis has been demonstrated in our research Jabora- tory and plans are now being prepared for its use on a west coast office building. INST ELATION OF CV PANEEWALL Techniques of installing precast concrete panels are well known to most contractors. The Arcadia Hospital panels, concrete with CV facing, were delivered to the job on large wooden easels and unloader] by fork lift trucks. Handling of the panels was facilitated by threaded inserts which were welcled to the re- inforcing mesh and into which steel eye-bolts were screwed to provide lifting points. The panels were then lifted into place in this 4- story building by means of standard rigging equipment. No serious problems were experi- encecT in handling the panels and the instalia- tion was accomplished by a masonry con- tractor in less tinge than originally anticipated. Attention is caller! to the flexibility of CV PANEL\VALL. Having proven the practicability of title precast masonry panel and having de veloped both the curtain wall panel ancT a panel for thinner window wall construction, it is ap- parent that the clesign possibilities of the panel are quite flexible and navy be adapted to practi- cally any type of construction by means of proper anchoring details. The curtain wall panel serves its best purpose as a masonry cur- tain wall incorporated in lift-stab, steel-frame or reinforced concrete frame construction, anc! - can readily be finished with low cost con- tinuous interior surface materials. COMPARATIVE DATA OF CV PANEEWALL In considering cost, the flexibility of the CV pane} design and proven economies of masonry construction will assure over-all economy when the building is ciesigned for this type of con- struction. Basec] on our present experience, we believe that a CV pane} can be cast and placer:] in the wall for very little more than the present cost of installing only the ceramic veneer fac- ing by the hand-set method; thereby saving a large percentage of the cost of the back-up wall. Obviously, the size of the job, type of building, anchoring design, etc. will affect the in-the-wall cost. it is estimatecl, however, that the cost of the curtain wall panel wit} compare favorably with prices now being quoted on bet- ter gracle, insulated panels of other materials. In Flaking any comparison of cost, it is neces- sary to list all costs of preparation, provision for proper anchoring, etc. Weight-saving is important in presentciay Construction. CV PANE1:WALL, in the 3" cur- tain wall thickness, weighs approximately 30 lbs. per sq. ft. This is most significant when you consider that handmade architectural terra cotta, approximately 4" thick backed up with 8" of masonry, weighs approximately 175 lbs. per sq. ft. Present day 1" thick adhesion-type ceramic veneer backed up with 6" of light- weight aggregate concrete a total thickness of approximately S" weighs about 70 lbs. per sq. ft. Tlle weight of the CV PANELWALL, which is approximately 30 lbs. per sq. ft., is less 65

than IF of the weight of a 17" masonry wall with which competitive panels are so often compared. Test panels indicate that a thin CV PANEEWALL for use in window wall construc- tion wiTi weigh front 15 to TS Ibs. per sq. ft. Since weight is an important factor affecting the sounc! transmission of walls, it is apparent that the use of CV PANEEWALL. where through-waTI natal connections are eli~ninatecI. will provide notch Tower sound transmission than other types of panel construction. In regard to color, the outstanding proven eludes manufacturers of ceramic veneer (archi- acivantage of CV PANEEWALL is the higI~-firecT, tectural terra cotta) throughout the United impervious glazed surface, available in practi- States. Continued research and development cally an unTin~itecT choice of shacTes of color work on tile pane:t is being done by the Struc- anc! finishes that will not facie under the bright- est sunshine anc] that are impervious to the action of corrosive atmospheres, thereby as- suring permanent beauty and Tow maintenance costs. Regarding the space saving qualities of our curtainwall panel, taxis pane:t reduces the re- quirecT thickness for a ceramic veneer faced wall frown S", which includes 6" concrete back- UP PIUS :13~" of ceramic veneer ancT mortar setting becl, to 3", plus whatever acIditional insulation or fire proofing may be required. The CV PANEEWALL for window wall con struction is approximately ~ 3/~" thic];. The Structural Clay; Products Research Foundation is actively engaged in a research program to improve the ceramic veneer panel construction and to assist in developing thinner and lighter panels. DISTRIBUTION AND 1MARKETING OF CV PANEL\V ALL CV PANELWALL is a developn~ent of the Architectural Terra Cotta Institute which in 66 ~ ~ , tural Clay Products Research Foundation anc! with their advice and help, n~en~ber com- panies are developing curtain wall panels ancT fastening cletails to fit the requirements of projects in various parts of the country. CV PANELWALL construction is available through ~nen~ber con~panies of the ATC:F who are now prepared to discuss the possibilities of this developn~ent with architects and engineers in any part of tile United States and whose policy it wit} be to see that such panels are- properly clesigned, fabricated and installed so. that a satisfactory result is assured.

A'ivences in Uses of Solute! Stone modern masonry natural stone and clay prod- ucts. We heard something on the clay products and now we wit! hear two speakers on recent advances in research on natural stone. I. T. McKnight Indiana Limestone Institute. Bedford. Ind. SIR. FISH:~:R: The scope of this conference is President of the Indiana Limestone Institute. He began his work there as a fez engineer. He has been associated with a number of com- panies in file Indiana and Texas limestone in- dustries and has a specialist's education in con- struction and administration. Fir. T. T. McKnight is the Executive Vice NATURAL buiTcTing stone, which has been e~n- plov;ecT for human habitation in all periods since the beginning of recorclec! history, is still the preclon~inant facing n~ecliu~n for natty of our finest structures clesignec! be; architects toga;. The method of quarrying stone, its fabrica- tion, its design, ancT its installation have, of course, varier] wiclely with architectural stancI- arcis emplov;ec] at the time. In recent years, because of the rising cost of construction, architects have concentrated on raclically single design co~nparec] with the typical architecture of yesterday. A prerequisite of this simple clesign 1las been the clesire to use thinner anci lighter walls. Our substantially ac- celeratecl research program has joined in this search. Eve have clirectecI our research thinking to a varied application of thin walls, using stone 67

as a facing, supplemented and coorclinatec3 with accepted installation media in individual com- plen~ent or in packaged arrangement. The steps we have taken in the Institute clevelop~ent program are the result of in~- ~necliate de~nand. Thev represent only a be J J ginning. \Ve will continue to improve all our projects. five also intend to increase our breacith of imagination and our usefulness to the architect who strives to design buildings which are not only different but better. Many of the projects we will discuss here ave been developed by our engineers and researchers ancI will, for the most part, employ Indiana limestone. Many of these projects, however, are aciaptable or applicable to other natural limestones, such as Texas, ATaban~a, Minnesota and Kansas. ~ would like to take just a n~on~ent to ex- plain Ranclo~n AshIar or Rubble Veneer. There scenes to be a neecT for clarification of the use of this material for proclucing and ap- plying to the building. Ranclo~n AshIar cliffers a little front rubble stone, as you have exact sizes in heights, run- ning 7~/~", 5" ancT 73/4", ant! with a i/2" mortar joint, can be coordinated with brick for cle- sign purposes. You will find the Random AshIar type of stone more prevalent in lime- stones, such as Tncliana, Alabama, Texas, Kansas and Minnesota. These stones permit the quarrying of large size blocks and through the process of sawing can make the regular course heights. Rando~n AshIar is shipped to the job site in promiscuous lengths whicl1 provides an op- portunity for the mason to set it in a practical and economical manner, as he can break the stones to lengths required at the job site very easily with a masonry saw. ard course heights. This type of stone permits an even more random, or rustic effect. The Rubble stone is usually found in a variety of colors, ranging from white to a dart; pink or red. Until recently, it was necessary to hancIle random stones in individual pieces, which was very tinge consuming and expensive to the producer anc] consumer. This type of stone is now buncIlecT with metal bands faith a ton of stone to each bundle. The loading and un- loading problems have been ~nini~nized by palletizing to the point where it is very advan- tageous to both the producer ant] the con- sumer. Rando~n AshIar and Rubble stones have increased in popularity because of the cle~nancl in the residential construction field for a material with durability and beaus`; which is ~naintenance-free. For the most part, Random AshIar or Rubble stones are confined to resi- clential construction. They are also a(laptable to co~nn~ercial or religious type buildings, however, when used with a cut stone trim which provides a very pleasing contrast in color and texture. Because of the popularity of these products the Institute research department has given high priority to the developn~ent of a thru- wall unit. We specifier} that the exterior of this consulate unit was to be stone resenting Ranclon~ AshIar. What resultec] is a thru-wall unit using 3" of stone as the exterior, 2" of a rigic] type insulation, such as foam glass, ant! 3" of natural stone aggregate which serves as the interior ant] can be painted or plastered. The aggregate nude front natural stone waste can be permanently color stained ashen cast. The tllru-wall unit has a very good insulat- ing quality, taking advantage of the insulating Rubble stone, often referred to as "Native material. It gives an average U factor of .~. Stone" because it can be found in practically The unit has been designed for ease in han- every state in the Union, is also shipped in filling and will be principally 5" high and 74" promiscuous lengths, but does not have stand- long, although this is not a strict Imitation, 68

HONIE IN INDIANAPOLIS, IND., BUILT WITH INDIANA LIMESTONE. FRANK HOCHMILLER, ARCHITECT as it could easily be 30" long. But, in general, we have fount! Flat tl~e lighter the unit, the quicker its acceptance by builders. The thru- wal1 unit will provide the builder with a con- struction material which is beautiful. has in- sulating value, is maintenance free ancl fire- proof, and has a very Tow per square foot cost. The cost in the wall will vary, of course, with freight rates, setting costs and other fac- tors involvecI. But we do know frown surveying LIMESTONE THRU-WALL UNIT the market that the thru-wall unit is lower in cost than many competitive materials. There is another application of stone serv- ing both as the exterior and interior for trim work around windows. It was developed to be used with either the tl~ru-wall unit or for ac- ceptance in the prefabrication field. This ap- plication is for winclow surrounds, using a snooty finish stone, I" thick with 3" of in- sulating board ant! a sprayed-on aggregate which serves as the interior. The interior sur- face can be painted or plastered. LIMESTONE M7INDOW SURROUND The stone, insulation and interior finish surround the window franae in any size (le- sired. In other words, it permits the place- ment in the builcling of the window frame, stone trim and interior as one unit. We believe this wit! permit our entry into the prefabrica- tion field which is Seconding more and snore popular. On the two above-Inentioned projects, T have referred to rigid-type insulation. There are a number of rigid-type insulating materials which can be used, including foam glass as 69

n~anufacturecI by Pittsburgh Corning Corpo- ration, or Tectun~, as manufacture by Tec- tu~n Corporation of Newark, Ohio. These are the materials we leave worked with in our lab- oratories anc] which have proven successful al- tLough there snap be equals. As you all know, the application of water- proofing materials on n~asonr~' has become very; popular in the last few ~ears. For the LIMESTONE WINDOW SURROUND 70 most part, these materials leave been ~isusecI because they have been applier] to prevent staining or discoloration rather than for tiled purpose, wick is to increase tile flow of water frown the surface of walls. At least that has been the experience of the Institute fielc! en- gineers. You are all acquainted with tile prob- Ic~ns of construction and know the situation teat can be created by water getting into the wall Juring the period of construction. Natural stone is often blanked for discolor- ing and staining when actually the material is not at fault. Natural stones, for tile most part, do not 1lave any staining qualities in their physical or cLen~ical n~akeup. Stain- ing occurs when water has been permitted to get into the wall cavity and carry soluble salts or alkali frown tile back-up n~aterials tl~rougl the stone to tile surface by capillary attraction. Staining can be prevented with proper precau- tions but, of course, we have no control over tile elements of weather. The probes of staining anc] cTiscoloration on natural stone are now being solved through tile application of waterproofing material nanufacturecT for use on limestones only. For instance, the Institute has cTevelopecT a water- proofing material Illicit takes advantage of the very clle~nistry within Incliana I,in~estone. Taxis waterproofing material wl~icI~ is aciaptable only to TncTiana Limestone will not discolor the stone after application as will some of the co~n~nercial products. Front all laboratory tests we leave fount] that all indications point to a snore lasting or durable waterproofing than some now found on the market, yet it does retard absorption of water anc] permits a free flow front the surface of tile material. We know that oilier natural stone producers are working on else same project. Tile Tnsti- tute's waterproofing material wit! be releaser! ancT n~arketecl in the near future for application on IncTiana 1,i~nestone. As indicatecT, frown all tests ancT laboratory ciata. we believe this will

THE SAMPLE OF LIMESTONE ON THE RIGHT SIDE SHOWS THE EFFECTIVENESS OF THE WATERPROOFING MATERIAL DEVELOPED BY THE INDIANA LIMESTONE INSTITUTE reduce our problems of staining and cliscolora- tion by 90 per cent. T\Iorc an(1 snore si~nplicitv; in design secrets to be tile keynote of modern buiTciing, and along with this has gone tile reduction of wall weight and a trencI towards timider walls. :En keeping witty this trencI, tile Institute leas first designed a ~nasonrv wall using a thin veneer stone 3" thick, backed up witty a rigi(l-type insulation. Talc tI~ickncss of talc wall was re LIMESTONE THIN WALL PANEL c:Tuce(1 yet the structural and insulating quali- ties were maintained. TIlis thin veneer used with an insulating material was first employed in the Labor-In(lustry Builcling at Harrisburg, lea. On this building, foam glass was applied to tile back of the stone to maintain insulating qualities. Our experience was very satisfactory on the Labor-Tnclustry Building and as a result that type of wall design has been used in other buildings throughout the Unite(l States. This >~:as one of our first steps toward reducing wall freight in conjunction with the popular cur- tain wall design. The next step towards rcclucing wall weight \57aS tile development of a panel using a nun~- i~er of pieces of stone applied to a single piece of rigicT-t~pe insulating boars:] by mechanical fasteners. This type pane! is now being used in the Meadows Shopping Center in Indian- apolis, Indiana. The panel used on this project was 10' long, 30" wide. This, however, is not limitation in size. Aside front the panels being vised in the project, they were tested in the mills and handled in a very destructive manner 71

in an attempt to breal; the stone front the in- sulating board. :~ Tile panel provides an opportunity to False use of several stones economical to fabricate in size, but which, when applied to the insu- lating board, can be hoisted into the wall as one unit, permitting an increased square foot coverage at the end of the work clay. Our ex- perience to date has been that masons, al- though they were not acquainted with the use of the panels, have been able to set over 1,000 square feet per working clay. The insulating value of this panel, using 7" of stone and 7" of Tectun~ is .18, or the equivalent of 5 feet of solid concrete in insulating value. Tile pieces of stone are applied by n~ecllani- cal fasteners. The panel is then anchorec! to the building with strap anchors ant] dowels. For the most part, the panel is attacLecT to tile wall in Ducts tile saline manner as stone is co~nn~only applied. Details and specifica- tions on this pane] will be released in a very short time and Oracle available to architects and builders. :E have spoken at different tinges about con- trast in color and texture. ~ know that you are all acquainted with the clen~ancT for color anct how it is being used very attractively by the architect in light and dark shades. The In- stitute has developed a penetrating stain which can be applied to a natural stone without destroying the natural texture or appearance. This coloring process is not a paint, but a penetrating stain which is applied with special equipment. Front all tests negate in inde- pendent laboratories we can state that the colors will last 15 years and probably longer. Standards and specifications are being pre- pared for this penetrating stain using basic colors at this time. Through the use of this penetrating stain we can provide the architect 72 and consumer with a colored product witl1 clurabiTity and all the advantages of natural stone. jive anticipate that this colored stone will be used for the noose part as a contrast with the color of natural stone, which is usual- Ty lighter. For instance, a l~uilding is now under con- struction using a standard buff ashIar fielcI, which is a light wand color, with dark gra!, Indiana Limestone with the penetrating stain applied for window surrounds and entrance features. This penetrating stain is another new product which will be prepared and distribute~l in a very short tinge. As ~ indicated at the outset of this presenta- tion, ~ have been talking about clevelopments in the Indiana :Lin~estone Industry for the roost part. It is only because T ant most familiar with this program, having been as- sociatecl with the Institute for several years. [however, ~ know that great strides have been made by the other natural stone producers and they, too, wit! provide the architect ant! builcl- ing owner with new designs and new applica- tions. Tllese projects undertaken by the nat- ural stone industry have been designed to pro- vide the architect with new and n~oclern ap- plications of stone that can potentially be user! for some of the Tow-cost buil:ling programs, such as schools anct residences; but also it can be used in practically every elements of the con- struction industry, including con~n~ercial anc! religious buildings. In conclusion, let Nile say that tile natural stone industry is making every effort to provide tile construction industry with new, more ef- ficient, and less expensive applications of nat- ural stone. We believe architects and buiTcling owners who use masonry and natural stone have something both new and exciting to fool: forward to in the future.

Marble and Granile Research MR. FISHER: Our next speaker is Vice Presi- dent and General Sales Manager of the Ver- mont Marble Company Mr. A. T. Howe. ~ understand Mr. Howe started in the marble business 47 years ago as a young man when he MY subject is "Marble and Granite Re- search," but as I speak in this instance for the Marble Institute of America, I may easily omit reference to granite. Please understand that in many instances what is stated about marble could also apply to granite. Marble is one of the oldest known materials for use in n~onun~ents and buildings, for it was used long before the birth of Christ, and its A. T. Howe Vermont Marble Company, Proctor, Vt. carried water that was thrown over the slabs of marble for their gracling. Mr. Howe has a very long career anc] inti- mate contact with this great industry in our fieZ(l. use continued on down through the ages. It Is old, yet it is ever new. . On the other hand the word ''research'' has become associated in the minds of many peo- ple only with new products and materials. In nay book that is only one kind of research. To us in the marble industry, research means not only finding new applications for an ancient material, but discovering in the shop, in the ~3

laboratory, and in the field, new methods of manufacture, new newels of installation, and new waves in which to drake the architect and builder constantly and actively aware of n~ar- bles in their 1noclern dress. [ have with Nile today several illustrations of what is being done throughout the country with marbles activities which prove that marble is ~naintain- ing its pre-eminence in the buiTcTing field. ~ shall say nothing regarding beauty, charac- ter, infinity of color, durability, and easy anc! low cost of maintenance of n~arble, nor shall ~ discuss the beautiful builcTings of yesterday (and for that matter, of the day before yester- day) which have employed marble with such high standards of taste anc! design, sonic of which we see around us today. Modern architecture, the architecture of tomorrow, has been called many things, both good and bad. T want to go on record here ancT now to say that ~ think much of it is good. ~ don't nosed, of course, that every buiTcling erected today or from now on wit} be a work of art, but, generally speaking, that concept of architecture which sets up a strong, slender, steel France on which are hung floors, walls, and all elements of the building, cannot be ignored. We in the masonry industry must adapt ourselves to the spirit of this type of architecture, and we are so doing. The stimulation which only classic materials can inspire, plus research, will give the archi- tect, the contractor, and the owner that which is desired. The direction of our research was stimulated by new architectural design anc! its demand for thin and lightweight walls. Our research takes into consideration the prepara- tion of units which can be instalIec! snore economically. Basically, the new architectural design is aimed at reduction in the cost of material anti its installation. ~ would like to show you some illustrations of the results of our past research and some '}4 i. . . . . ~ . . ~ T..: , . .. .... _ I I. ~ ~ ~.~.~. ~. ~.~. ~.~ . ~.~.~.~.~ . ~ ~ I ~ ~.~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ I I ~ FIGURE 1. State Office Building' Pittsburgh, Pa., financed by the General State Authoritv' now . ~ . nearing completion. Of the tilings we are working on now for the future. Figure ~ is a progress photograph of the Pennsylvania State Office Building which was financed and built by the General State Au- tI~ority in Pittsburgh, Pennsylvania. it repre- sents a good example of veneer application of n~arble. The ~ I/4~, thin stabs of marble are securely anchorec;l into the masonry bacl:- up which progressed at the same tinge. This is typical, of course, of the practice of veneering. Veneering of marble is excellent practice in no(lern construction and plays an important role in the n~oclernization of older buildings as well. Figure 2 shows the exterior of the National T]eaclquarters Building, International Brother- hood of Teamsters. Here is another fine ex- a~nple of the marble veneer wall with masonry '~ack-up. It is, as you can see, a new building. Those of you who know Washington, D. C., will easily recognize it. Figure 3, the Equitable Life Building in San Francisco, California, is yet another modern example of marble veneer construction. The method of applying marble veneer is a familiar one. Specifications for it are set fortes in a booklet called "American Standard Specifi

cations for the Support Anchorugc and PIO- tcction of Extcrior Ample Veneer 2/' and Lass in Illickncss and Exterior Marble Used in Cur- t~in or P~ncl Shahs' In spite of thc length of the tide, the spcciEc~tions thcmselvcs, ~ldlc thoIougb, are contained in just ~ fc~ panics. You Al bc intcIcstcd to 1carn that thc latest cdihoI1 of thc book has ~lrcudy been ~idc#< distributed to ~Ichitcctur~1 offices throughout the land. It ~ avad~blc from the o~cc of the Warble Institute of America Mount Vcrnon, Nc~ York, to any who Aqua it. Vcnccr construction, ~ product of rcsculch, Ads dcvclopcd to meet the dcm~nds of modern architcctura1 design for ~ thin, lightweight malt gild thcrc arc many more cxamplcs of madly used in this manner in ~N our savior cities. Industry rcsc~rcb bus gone on to Fact cvcn more rigid demands for thinner malls and prc- ~sscmBlcd units the curtain ~1t Ibc S2I~C rchitcctur~1 dcshcs which brought about thc vcnccr applications which can be dchncd as ~ covering for masonry construction, now h~vc gone farther and dcm~nd ~ ~N that is not only ~ covering but ~ complete through-thc FI~RE 3. The Equitable [1~ Building, San Francisco, California, illustrating the use of 2 marble veneer construction. ............................... I I ~ ~ I ~ !~ ~ ~1!~ - - - _!!!! ~SS~S it. .. - HI _ _s Sib: Sib Am: a: I ~. ~. . ~. . . ~. . . . ~ . ~ . ~ ~ ~, ~ ............ . ... ....... ...... ....... .. . . .... FIGURE 2. Matinal Headquarters Building, Internationa1 Brotherhood of Teamsters, ~ashi-it~n, D. Cal another example of marble veneer construct10n. ~5

FIGURE 4. West Columbia Elementary School, West Columbia' Texas. Marble slabs were used above as well as below all windows. . :>Aj~! ~l_~A54'C ~ SECTION A-N SCALE Aid = 1 0 bCtiF:DULE 0E,~,~621ALS ~ A ~ ~ L I- ~-~ - Co,~'C~ETL i'; ,~':' 1~;;: W;1 L.,~ IN'jU' A:10,~ j M I:: 1. A 1: raid ll~ )-v l l y~ PLAN D-B SCALE 112 ^ 1-0' ~ L ~ V A T I ~ N 1 ~,74-~ _ D4~fLS <~-~,~Lr F. by tQI ~SCALE lb 1-O ~'~'~'~'~'~'~' ~'~'~'~'~'~'~ ' ~. ' ~ . ~ I. ~ - '' i:' '''-at _ __,, FIGURE 5. West Columbia Elementary School' West Columbia, Texas. The -~/8 " marble slab being, tilted into place constitutes the entire thickness of the wall. FIGURE 6. Detail Plate No. F from Marble In- stitute of America's Standard Specifications For the Support' Anchorage and Protection of Ex- terior Marble Veneer Two Inches and Less in Thickness and Exterior Marble Used in Curtain or Panel Walls. 76 FIGURE 7. Gulf Oil Corporation Building, At- lanta' Ga. Exterior marble being set into place from the inside of the building.

wall unit. It was required that this unit in- clude insulation equivalent to masonry back- up, and even an interior finish, installed in franking or without it. Our research is geared to the fulfillment of these desires but with the realization that heavy, cubic construction ant] veneer treatments over masonry will always have a place on ~nonu~nental anc] enduring structures. What has been accomplished by research in these newest concepts of architectural design? What problems were faced in providing eco- no~ical curtain walls? There were, of course, many problems, but ~ should like to say There that one proven we did not have to face was tile performance of tile marble itself. WhetI~er -~&" in thickness or thinner, or seven feet thrice, marble still retains its dimensional stability, its characteristic beauty;, its clurability, its Juxu- rious appearance, its economy and low ~nainte- nance. We will not go deeply into all tile details of tl~e problem. Their enumeration, however, would give an indication of tile extent of our energies to accomplish the objective. Rather let us examine several snore photographs which show typical curtain walls of marble or con- struction details that speak for then~seives. As the first photograph, (Figure 4), it would seem appropriate to show the simplest of all curtain walls. Here is a photograph of the West Columbia Elementary School, West Columbia, Texas, which consists of large slabs of marble As" in thickness under anc] above windows. As you can see, the erection was simple. The marble was installed in sash ancT then the retaining frame screwed into place (Figure 55. This wall had no back-up, no insulation,- it is the wall. This is in a southern climate, to be sure, but how simple it would be to attach insulation and interior finish to a similar in- stalIation where climate snakes it necessary. Figure 6 shows the detail followed in the In- ternational Business Machines Building in Kingston, New York. This is Plate F in the M.~.A. Specifications booklet. Figure 7 shows how the marble, the exterior marble, by the way, was applied or set in place front inside the Gulf Oil Corporation Building in Atlanta, Georgia. Figure ~ shows how the rigid insulation was applied directly to the back of the slab. The interior plaster wall, by the way, was applied directly to this insulation. Inciclentally, the building was built in 1950, aIn~ost six years ago, and any reason for showing it was simply to point out that the research carried on by the industry in the past was not without its results. As you can see front the vertical section shown in Figure 9, the Hi" exterior marble FIGURE 8. Rigid insulation is applied directly to the luck of the marble slab on the Gulf Oil Corporation Building,, Atlanta' Ga.

If i__ ~. AL Cat C --''''iffy C=. 'A 'a 1-~ 4~_?.~ 2' ~ ~ t~ i i! it ~ -1` ~ f''f'"''-- -.:::$:: :::.:X *:: :: jl 'I _ I'.: _ _, '~ a a ~ care 4A _ PARTIAL ELEVAT10~ AT i SCALE Act ~ ~-O 2~THE oFF:lCF biDG ~72 -HEGULt~olL`02P, ATLAN7A,GA. ' 1 H PE1 A2(HIfCC1-- STEVEN', 4 ~VIL<1~50N, ASS=l^1E AQC~iT5Cr5 <.r y TO ~lAlf COALS ~ AWLS kP ~I . ~ <~ Y tools I r V1 L I 5LCT10\ A-A SCALE 1~"- 120' T~A2B' -: ~ ~ N :-B ·'(,kLL. 1'.1''-l'O' l ~r I_ ~ Car ~ O ~ 5-5 = t _~_J l _ -'-f 11 I._ FIGURE 9. Detail Plate No. D from M.I.A. Stand- FIGURE JO. Marble Curtain Mall Panel IJnit ard Specifications showi;n~ section through Gulf Oil Building wall. "A" shows marble plus insulation. -.B-- shows marble plus insulation in marble France on hack. "C" shows marble plus insulation plus interior enable. FIGURE 1l. Marble panel with insulation and in- FIGURE 12. A detail of the corner of the panel terior finish all enclosed in metal frame and showing how the panels interlock during erec- readv for immediate installation at the job site. lion of the marble curtain wall. 78

panel is backed up witl1 1~2" parging and air space which, with the 3" rigid insulation, finished on the interior with 3/~" of plaster, makes the total wall thickness just 5~/~". If the thin curtain stall or panel wall type construction had cone along before we knew how to cut marble into thin slabs, ~ really don't know what we'd have done. Fortunately, how- ever, long before ~ became identified with the industry;- and that goes back nearly half a cen- tury-equipment was available which was ca- pable of cutting marble into 2", I", and even i/2" slabs. Most of this marble in the thinner dimensions, as you well know, was confined to use in building interiors. Even with the equip- ~nent generally available today, special care must be used in cutting marble to the smallest thicknesses. But machines, which are now be- yond the development stage, will be able to economically cut marble as thin as its struc- tural strength will allow, and it is here that the architect, the designer and the building owner can take advantage of the unique virtues of marble. For whether the marble in a build- ing is -~8", 7", or 7 feet thick, it still has the lance beauty; it still has the same luxurious ap- pearance; it still retains its color, its pattern and its features of low maintenance and easy installation all the features which you know, and which T promised not to mention, but T clot The current trend is towards further reduc- tion in weight, not only in the marble itself, but in an entire, packaged, through-the-wall unit. Also, there are many advantages to hav- ing the exterior facing, the insulation, and even the interior finish supplied to the job site in one package. Perhaps the principal advantages would be those of simplifying the erection and reducing the cost of the installation. Working along these lines, the industry has progressed far in creating these units, some of which are indicated in Figure 10: A- Marble plus insulation B Marble plus insulation in marble France C Marble plus insulation plus interior marble Here we have three typical ways in which marble can be designed into curtain avail panels. "A" shows marble witl1 insulation attached to it. This is very much like the panel used in the Gulf Oil Building (Figures 8, 9, 10), but remember that this panel would be delivered to the job site as a unit with only setting into the France to be completed in the field. The center sketch, "B" shows another method we've been exploring. The back of the marble is franked with 2" wide marble strips which are securely attached to the slab. The insulation is fastened against the back of tile slab in the recess formed by the frame. Tile frame of marble gives better bearing and it also provides deeper ~narble-to-~narble joint- ing, which is desirable. In addition, it gives the necessary support to the insulation in handling and erecting. Plan "C" shows tile complete curtain wall package unit with exterior finish, insulation, and interior finish, delivered to tile job co~n- plete and ready to install. One of the most interesting phases of re- search consists of the work done to forn~ulate marble panels in sturdy metal Frances. Tnter- locking, insulated Novembers which can be snapped into spandrel framing in the building have been developed. Figure IT is a general view of the panel. Figure 17 is a detail photograph showing the France close up. You can see here how the n~en~bers interlock; note the groove and slot provision for snap-in installation. Specifications on this panel are: Marble Ozark Famosa Finish Hone Finish ~ Waterproofed ~ insulation Styrofoam #33 ~ Expanded Polystyrene ~ Back FIextos Board Adhesive Permanent Fire Retardent Sur- face Coating 79

Calking Con~pound Thioko} Base France Alun~inun~ France designed to be used with curtain wall system Weight ~ 04 pounds ~ including frame ~ Dimensions 4' 7-5/16" ~ 7' 6-~" to out- side of France Panel thickness- ~ 3/4" This panel, inclucling the France, insulation, and backing, weighs less than 9 poun:ls per square foot. These are not the only innovations being researched by the marble industry. Although will not have tinge to go into then in detail, ~ want to list a few other areas into whicI~ our research program is leading us: New finishes for marble for exterior use that wouIc] enhance tile natural color anc] markings of the marble. New and improved ~nethocis of anchoring marble to the structure of tile building. iNew and in~provec] n~etho(ls of packaging marble for shipment. marble used as masonry, but there are many applications on the interior where these ideas have great potentiality. These projections of research are presented with the full realization that much engineering ancT architectural design will be needed to adapt talent for specific installations. The marble industry looks forwarc] to new suggestions and ideas, to further experin~enta- tion, where advisable, by, for and with the architect, contractor and owner. Veneer or curtain wall, or a combination of both, in marble can ancT will be pro~idec3 if specified. The supply of marble is unTi~nitecl, and ex- perts tell us that it will not be exhaustec] for thousands of years. The marble industry is well prepared to provide marble for the heavier walls, for n1onunlental buildings, as well as to provide it in thinner slabs. Marble, one of the oldest of building ~na- terials, is modern through the ages and will continue to be modern because of its adapt- I have confined n1y remarks here to exterior ability to changes in architectural design. 80

Brick anti Tile Research Robert B. Taylor Structural Clay Products Research Foundation, Geneva, Ill. MR. FISHER: Our next speaker is the Director n~enclous results out of this laboratory in the of a great new laboratory that is now serving coming years and for exciting things right now. the masonry fieZc] the Structural Clay Prod- Mr. Taylor was educated at Denison Univer- ucts Research Foundation Laboratory at sity and at Ohio State. He is a member of the Geneva, ~ZZinois. This little laboratory, I'd like to mention, has space inside for the erecting of large fuZZ-size structures, one and a half to two stories in height. ~ think we can look for tre THE Structural Clay Products Research Foundation was organized in 1950 by clay brick and tile manufacturers in the United States and Canada to undertake research ain~ecl at improving the competitive position of brick and tile in both present and future markets. Its membership has subsequently increased until today there are Il0 U. S. and 28 Cana- dian manufacturers participating. This re American Ceramic Society, a member of the Building Research Advisory Board, and a rep- resentative to the Building Research Institute from his Research Foundation. search effort began as an exploratory five-year program with its future beyond that date to be reviewed at that tinge. ~ total of one and one- quarter million dollars was subscribed by the nen~bership for this exploratory period. At the end of three years, however, the membership had seen sufficient results, and couIcl see suf- ficient future progress, that it clecicled to estab- lish the Foundation on a permanent basis. The 81

income of the Foundation today is approxi- ~nately $500,000 annually, and it has current assets of nearly one and one-quarter million dollars. This reserve is intended to sn~ooth out any ups and downs in the sales curve of the industry and will permit the Foundation to undertake important Tong range programs rather than planning expecliently on the basis of each year's income only. The current operat- ing budget is approximately $500,000. Since its very beginning, the FouncIation's principal research objective has been what we call "end-use" research, dedicated to seeking means for putting our industry's products "in- the-wall" at a lower total over-all cost. Three approaches have been taken to in~plen~ent this ob Active. No. I, we have critically exan~ined many current wall designs to detern~ine if a sin~plifi- cation of wall design will utilize the strength of our materials snore efficiently, or improve the performance of the wall. No. 7, we have also looked into the design of specific clay units for specific markets to de- ter~nine if changes in unit design could be Inane to simplify wall construction and recluce over-all wall costs. No. 3, we have critically exa~ninec] site con- struction techniques to determine those con- clitions at the job which should be elin~inatecl or modified to improve both mason and laborer productivity. in connection with approach No. ~ above, the "SCR insulated cavity wall"* was devel- oped. Tllis wall, incorporating a special low density porous insulation especially developed for it, gives a U factor of 0.17 with exposed masonry on the interior and exterior surfaces ant] at the same tinge performs as a true cavity wall in preventing transfer of moisture front the exterior to the interior. Other walls are also being studied to determine possible ~noclifica ~ Reg. T. M., SCP~F. "* :Reg. U. S. Pat. cuff., Pat. Pend., SCPRF. B2 tions. This is particularly- true of n~asonrv walls normally thought of as non-Ioad bearing ele- n~ents. Tests to date indicate that many such partitions of relatively thin thickness have very real structural strength ant! naight well be con- sidered as economic load bearing elen~ents in a structure. For example, a 6" facing tile partition built of 4" units and 7" units leas been found to be a very efficient load bearing elen~ent. The first result of approach kilo. 7. improve(1 unit design, was the development of "SCR brick,"** first announced to the construction industry in May of 1952. This unit leas (le- veloped for the large percentage of current home building that is one story in height. It builds a single wythe wall, non~inalI~ six inches thick, that does not require either n~asonr,v or France structural back-up materials. Because only 4~/2 units must be laid per square foot by the mason, it radically reduces the number of units he must lay per square foot and increases his wall area production per day be; nearly 10040. To date more than 30,000 "SCR brick" hones have been built and the sales curve is still rising sharply. it has definitely been estab- Iished in many, many areas of the country that "SCR brick" hones can be built and soIc! di- rectI~: competitive with quality wood France construction. In addition to its original application for one-story hoInes, physical tests of the "SCR brick" panels have indicated that its properties make it suitable for many other applications. Schools have been built with it. In several areas of the country it has been used for very satis- factory, economical curtain wall construction in n~ulti-story buildings. Motels, one-story fac- tories and Toad bearing industrial partitions leave become a developing market for it. Its properties are sufficiently unique that we be- lieve that it can also serve as the load bearing France structure for certain types of cellular n~ulti-story buildings, ten to fifteen stories in

height, as described in the Architectural Rec- orc] in 1952 by Davison and Monk. In regard to approach No. 3, improve site techniques, we have looked critically at the site problems of both the Nelson and the laborer. In regard to the reason we have found that continuously; adjustable scaffoIcTs, which keep the mason in an optimums working position with respect to the wall lie is building, can narkeclly improve his productivity without in- creasing fatigue. In these scaffolds provision is also noble for keeping the ~nason's supply of brick and mortar at a convenient height ant! location behind him. These improvements in scaffolding techniques by actual test have clen~onstrated that they can improve his pro- cluctivits: between 20 ancl 25Wo. As a result of the Founclation's work in this scaffoIc} field three new scaffolds of this type are now on the market. The "swing" scaffold for ~nulti-story construction work is also ideally suited for this purpose, provicled it is sufEcien.- Ty wide to install a material platform of proper height behind the n~ason's working position. N;Ve have found that a n~arkec] nylon line which is now available for both modular and non-modular units can reduce costs in the original AN, bonding of a wall and can also aid tile mason in keeping bond throughout the construction of the wall. Tile strength of this line in comparison to its weight permits longer lines to be run with fewer intermediate sup- ports and thus can speecI up the work ancT i~n- prove workmanship. More than 200 buildings of all types, sizes and encI-uses have been built by contractors employing this complete "masonry process." We know that it does work, that masons are receptive to it and in notary areas are using it effectiveIv at this moment. Their productivity J ~ increases are resulting in a n~arkecT reduction in masonry construction costs. In the field of laborer economies we have developed a new type of brick and tile package for the handling of our products by mechanical means from the plant all the way to the scaf- fold position of the mason at the wall. In its brick form, the package contains 62 brick naiads up of three strapped bundles of 20, plus 2 spacer brick. This package is adaptable for both large and senate types of construction, by both large and sn~all contractors, and can be handIec! by hand trucks on small jobs, or in n~ultiples on large jobs with mechanical fork lifting equip- ment. One contractor on a senate house saved snore than $~.00 per thousand brick through the use of this package. This package is not currently economical for our members to pro- cluce by hand strapping and assembly ~nethocls. 'Therefore, a year ago we began the clevelop- ~nent of an automatic packaging machine which will produce these packages at an eco- non~ical cost at the rate of 100,000 brick per (lay with a ~ninimum of plant labor. This n~a- chine has been completer} ant] is now being Inane ready for a plant trial installation. In sun nary of our attendants to lower wall costs, we believe we have Oracle real progress already and that some of it is being effectively used in the fieTcl today. We are also very hope- fuT tint much more of this current work wit] have a real impact on the construction inclus- try shortly. Awhile new products were originally subordi- nated to our "end-use research," they are be- con~ing an increasingly important factor in our development work. While "SCR brick" is prin~ariTy a new unit design it is also a new product in terns of manufacturing and pro- duction problems. We now have 77 manufac- turing licensees, and it has established a very desirable economic place in our inclustry's sun. Another new product, designed for a specific market, has been named "SCR re-nu-veener"*. This is a 3/4 inch thick clay stab with a "Nor- man brick" face size. It has a special) shape geometry that permits rapid attachment of it * Reg. T. M., Pat. Pend., SCPRF. 83

to existing wood or fiber sheathing with spe- cial metal clips to hold it in place. The joints are filled with a real mortar applied through a special pressure gun which we have devel- opecT. Special L-shaped corner units are en~- ployec} so that a genuine brick appearance is achieved. Economic studies inclicate that it can be applied in place and be directly cornpet- itive with many types of residing materials on the market. It also has a very definite place for interior redecoration of existing buildings since it will not require the strengthening of walls or floors to carry its weight. It is currently being test n~arketec! in the Colun~bus, Ohio, area to learn marketing techniques and facts prior to its national introduction to the builcting indus- try. If this new product reaches 10% of its po- tential market it will provide a 58 nonillion clol- lar annual market for our Industry in a ren~od- eling field in which it has never hac] a major foothold. At the present time in another of our major markets it has been established, and ~ ant sure it will be confirmed! tomorrow, that masonry curtain walls are one of the n~ost economic forms of construction available on the market today despite all cIain~s to the contrary by the pane] wall people. Even in the matter of speed of building enclosure, the proper size mason crew for a job can still keep up with the other trades that must complete their work in the over-all construction schecluTe. The one dubi- ous advantage that panel walls today might have lies in their reducer! thickness. In order to protect our future economic position in this field we have been carrying on considerable long-range work in precast panelized wall sec- tions for exterior curtain wall applications. NVe have developed an extremely fast setting cement grout which wit] enable us to produce such panels without large nooks investments. In its exterior applications, such panels are two and one-half inches thick, and reinforce(l to carry tile required wine} anti other structural 84 loads. Only two sizes would be needed in any specific building. It appears that these panels can be produced at a plant price of $~.00 per square foot an(l installed with lath ant! plaster interior for another $~.00 per square foot. We have also produced a structural ceramic glazed clay tile unit four inches thick that has a sound absorption of 60N, and a sound trans- emission loss of 47 db. unplastered and 54 db. plastere(1 on the back sicle. Production equip- ~nent for this tile is currently being (developed. A process for the production of economic lightweight clay units has also been developecI, and is currently being refiners on a pilot plant scale. It wit! permit a reduction of weight for structural brick an(1 tile units of 40GNo in addi- tion to that weight saved through coring. In other words, a current five pound brick wouic! weigh three pounces and the eight pound "SCR brick" would weigh less than five pounds. This lightweight process provides sealed cells, and the water absorption of such units is not appre- ciably higher than current clay bodies. Our process, which we believe to be unique, will permit the production of such units by nearly every one of our November manufacturers de- spite the great variation in clay properties that exists in our industry. It will permit a greater control of unit size, and will make grinding to exact size an economic possibility. Best of all, it can be pro(luced with the existing facilities of our industry without requiring that they be obsoleted or discarclec] before this development can be offered to the construction industry. Another important current phase of activity of the Foundation involves physical research to learn new facts about the behavior of clay masonry walls front a thern~al transmission basis. ~ believe we have the most elaborate buil(ling thorns research program uncler way in the country. We have built six test buildings with six different types of masonry wall con- struction, ant} one identical builcling with metal pane} walls and another iclentical build

ing with wood France walls. Each building is heater! anc] eoolecT as desired by a special air conditioner and electrical heating device. Hun- drecis of thermocouples and dozens of heat flow meters are employecT plus a very elaborate control ancT instrumentation builcling. These tests are already showing that the thermal ea- paeity of masonry walls can be a deeicled factor in reclueing the initial size ancT cost of heating and cooling plants. They are definitely show- ing that the U-faetor of a wall is not necessarily the only factor that will cletern~ine the thorns perforn~anee in a building of a given wall eon- struetion. The first public progress report on the results of this research has been given to this conference earlier tociay by Mr. C. B. :Monk. Fundan~ental research into mortars has be- gun to show real progress. Certain cement eon~binations currently under study are devel- oping ultimate bond strengths in excess of 700 psi, instead of the name usual 50 psi. It is still a mortar that can be handIec! with the trowel. Funcia~nental research into efflores- eenee and greenstaining is cleveloping knowI- edge that is aIreacly being en~ployed in some of our plants to recluee this problem in wall ap- pearanee. Tmprovec] methods of cleaning n~or- tar stains from masonry have also been cle- veloped. In connection with effloreseenee, ~ would like to eall the following facts to your atten- tion. Sonnetizes on a given building, arehi- teets, contractors ant! owners fins! effloreseenee on eIay units which in the past have never giv- en then any trouble. It must be remembered that effloreseenee means that there was water within the wall to carry soluble salts to the sur- faee. Without such water, regardless of where it originates, effloreseenee cannot oeeur. We have also established that even if the brick is absolutely effloreseenee free, serious amounts of effloreseenee can result if there are soluble salts in either the mortar or the back-up ma sonry materials. It has also been established that even if the bricklaying workmanship is perfect so that water cannot enter the exterior face of the wall, effloreseenee can still occur if proper flashings have not been installed at crit- ical points in the building or if moisture vapor is not prevented by suitable vapor barriers front entering the wall from the interior side. A large amount of our work in the past and present involves architectural research studies. For example, facing tile shapes are being an- alyzed with a view to a sin~plification of shapes to reduce plant production and inventory prob- len~s as well as the design of such walls by the architect. It is believed that this study will per- ~nit more rapid deliveries of facing tile to the public ant! will make estimating of facing tile a much simpler procedure. Architecturally and structurally we have also stucliecT school construction requirements and costs. There has been a substantial amount of publicity given to purported] savings in school construction costs by means of prefabrication of buildings constructed of either metal or wood. Widespread claims have been made that such schools can be erectec] for the school boars! at classroom costs of 15 to 20 thousand dollars. This has been coupled with the claim that this cost is one-third or less of the usual typical masonry school which has been stated to be as high as 50 thousand dollars a cIass- roon~. Our school cost studies have shown the "per classroom cost figure" to be completely misleading. On a recent public platform with Nile one of the prefabricated school suppliers stated that they had just completed a six cIass- room school for $120,000, or $30,000 per cIass- room. The square foot cost of his buildings however, turned out to be more than AS per square foot of space. There are many, many masonry schools being built today in all parts of the country for costs of 10 to 12 clolIars per square foot. Further, they provide the school board with yearly savings in the form of low 85

maintenance and operating costs, real fire pro- tection for the students and the wealth of color ancT architectural form that architects can so well fit to the local site ancT surroundings. In a (lesire to provide a simplified design for even lower cost masonry schools we have also developecl a concept of load bearing interior wall construction that, in the Chicago area, can pennit econon~ical masonry school construc- tion at an estin~atecT $8.35 per square foot in- clucTing the mechanical services. ~ sin~ilar cost study in Texas employing this concept yielcled an estimated cost of $7.14 per square foot. However, contracts for three schools of this type leave since been let in Texas at square foot costs of $6.7l, $6.86 and $7.25, respectively. This is dramatic proof that real utilization of the structural properties of masonry combined with the attendant savings in the roof and framing structure can result in a balanced de . , . sign or maxllnum economy. A recent phase of our work that has been extremely interesting is a series of high explo- sive shock loading tests of various masonry walls. In the final test, ~ walls were simulta- neously tested in an octagon test-fixture ap- proximately 30 feet in dian~eter. Four of the walls were n~ounted as vertical beans, 9 x 10 feet in size. These were: ~ a ~ standard S" brick and block construction; (b) S" rein- forced lightweight concrete block; (c) 9" re- inforcec] grouted brick wall with the same amount of steed as in "b"; (cT) 9" reinforced grouter] brick wall with twice the steel of "b" and "c". The other four walls were testecI as horizontal beans with end restraint against pilaster-type piers to develop "arching" action. These walls were 10 x 9 feet in size. They were: ~ e ~ S" brick wall ~ unreinforced ); ~ f ~ 12" brick wall (unreinforcecl); (g) 9" rein- forced grouted brick wall with the same steel as "b" and "c"; (h ) 6" "SCR brick" wall with ~ pencil rods in every other horizontal mortar joint. 86 Forty-five pounds of high explosive were detonated within the octagon, developing a peak surface pressure of 140 psi for 3 miTTi- seconds. This is in excess of the energy im- puIse sustained at 4700 feet front ground zero during Operation Cue's atomic building test in 1955. At that time, wall "a" in a two-story home failed, and wall "b" in a one-story structure withstood the blast. In our test, these two walls were employed as control speci- n~ens to provide direct comparison with Opera- tion Cue performance. In our test, wall "a" was co~npleteliy de- n~olished as at Operation Cue and wall "b", which survived Operation Cue, was completely destroyed. All six of the other walls stayed in- tact and were all structuraZZy sound after the tests. This dramatically illustrates the fact that economical brick walls can be designed to withstand the tremendous lateral pressures generated in atomic blasts, earthquakes, hurri- canes and tornadoes. The engineering design criteria developed in this program are being assembled into a "hand-book for blast resistant design" to be released to the architectural and engineering profession this fall. We began our research effort in 1950 be J employing the technical and industrial re- search facilities and staff of Armour Research Foundation of Illinois Institute of Technology. This was supplemented by contractual arrange- ~nents for our architectural research witl1 tile architectural firm of Howard T. Fisher Nz Asso- ciates of Chicago. In ~ 95 ~ we leases] labora- tory space of our own to supplement the con- cract work, and began to acquire our own staff and equipment as our objectives and programs began to develop and nature. In 1954, our n~anagen~ent demonstrated its faith in its research effort by authorizing the establishment and construction of a new na- tional Research Center for our industry. It was built on a 15-acre site 40 unites west of

Chicago in Geneva, Illinois, and occupied last fall. \Vithin the engineering section of this buiTcling full size two-story tonnes, or two-story prototypes of a n~ulti-stor,v builcling, can be erected to stucly engineering ancT construction techniques anc] to develop short cuts that will result in lower construction costs. Space Las also been provided for the establishn~ent of pilot plant production lines such as for the automatic packaging machine and for tee pilot production of pre-cast wall sections. Facilities have been provided for engineering stucly ancl testing of full size wall sections for water penneabilit~i ancT for compressive, transverse and racking strength. Complete ceramic re- search facilities of both a funcian~ental and production nature Lave been installecI. En- gineering ancT architectural laboratories have been provicled. Sufficient :lanc] is available at the site to permit tile outdoor erection of full size prototype structures to test builcling tecL niques and materials clevelopecl in the labora- tor~;. For speciaTizec] personnel or equipment, or for certain projects of short duration, we still intend to employ tile services of establisllec! research organizations. The Foundation with its adequate reserves, new facilities anc] trainee] stab, is cleclicated to the in~prove~nent of masonry structures and to the development of more economical ways in WIliCI1 to buiT(1 tiled. Research leas given our industry a new Took into its future a new confidence in that future a future of better present products, and with new products for new markets. It has en- couragecl the Industry to increase its capacity by snore titan 20: in 1955 an(l 1956. Truly, research is enlarging tile frontiers for brick and tile and we are confident that our inclustrv will continue to maintain its pre-en~inent position in the construction industry, Motif today and to~norro~7. 87

Discussion M R . F ~ s H E R: Our first question is di- rected to Mr. Howe: With expansion and contraction in New England temperature ranges, what is the maximum size sheet recom- ~nended for n~arble veneer if maintenance of joints is desired? M R . H o sv E: T think we said this ~orn ing that the n~axin~un~ size is what the quarry would produce, but it would vary some on the quarry itself as to size. But I'cI think the naximun~ panels would be somewhere in the neighborhood of six to seven feet long and three to four feet high. Although the other clay we had one ~ 5-foot square. M R . F ~ s H E R: Mr. Taylor, what provi- sion was Inane in your blast tests to com- pensate for the pressure relief afforded] by the failure of walls in determining the resistance to the blast? M R . T A Y ~ O R: Tile velocity of the mass propagation and the short duration of tile total blast of only three milliseconds. Our pressure measurements incTicated that there was no cti~ninution of an;; specific wall, because two walls went out. M R . F ~ s H E R: Here is another question to Mr. Howe: Is any serious work being clone toward structural applications of natural stones, such as prestressed stone assemblages, utilizing new cutting methods and high strength, low creep characteristics of stone? M R . H o w E: ~ don't believe so. MR . FISHER: In these panels Mr. Taylor just spoke of, they are using the brick structurally there. ~ think they first asked that question, wondering if any similar work was being (lone in the marble field. MR. HOWE: I'm not on the research committee of our institute, but ~ have not heard that they are starting that as yet. M R. F ~ s H E R: Here is a question for Mr. Monk. If you had used a porcelain enameled pane] instead of a galvanized one, would your results have been any different? MR . M ONK: The only difference wouIcl have been in the color. And you will note that 89

~ e~phasizecT, but ~ clicIn't have a chance to explain it, that the France Lut was white. The metal hut happened to change to a ciark color, so we hacT two extremes of color so far as mass was concerned. The enamel, of course, wouIc] be somewhere between these two extremes. The difference probabiv wouicT be onIv in J J color, and therefore it wouicT be someplace between ~ ~ per cent ancT 50 per cent heat Toss in excess of what you can expect with Horns U factors. ~ R. F ~ s ~ E R: There is a general question to all of the technical speakers this afternoon. If the jointing material for masonry is more important than the masonry n~ateriaT itself, whv taken has this important factor of n~asonrv J J work not receiver] more discussion by techni- cal speakers of this conference? Before passing that question on, ~ wouIcl like to sac- it is no own ingression that a J J considerable portion has clealt with the rela- tionship to the jointing between panels. Who wouIc] care to comment? Mr. Taylor? \{ R. T A Y ~ O R: Front nay point of view, I'c! say it takes approximately 75 per cent of our total research, both in the prefabricated panels and research having to do with stanciard type units. AncT we have work, as ~ mentioned, where we have achieved 200 psi bond strength compared to '0 psi. We also have evaTuatecT mortars. It's a very important thing, because the strength of a clay wall is no better than that of its weakest component, which in this case happens to be mortar. And it is essential, to get the best results, that the design of our inclustr,nT's products follow the kinds of speci- fication we know will really give good per for~nance. M R. F ~ s H E R: WOUI] anv~oUv else like , , to comment on that last question? Mr. Mc- Knight? 90 M a. M e K N ~ G H T : T think, Mr. Fisher, along with joining mortar tilers has been quite a revolution in the mastic industry in tee last year with some new discoveries in mastics, which we Lave usec! in broadening our scope in joining these panels. M R. F ~ s H E R: How permanent are tee penetrating stains to outdoor exposure? Mr. McKnigllt. M R. M e K N ~ G T-T T: NVe have run some of the most elaborate barometer tests possible with the latest equipment. NVe know (lefinite- Ty that we can penetrate with special spraying cquip~nent the stain to a clepth of a quarter of an inch. Tllat is consiclrecT an average because we clo have some variance of natural n~aterial. Groin all indications frown the technicians and engineers, we can say, for all reasonable appli- cations, it is good for 15 years. M R. F ~ s ~ E R: Mr. Barnes, can satisfactory lateral (reflection of one story with respect to the next be per~nittecl, say /-inch per story;, with safety to the panels? ~ assume the ques- tioner has in noting! the wind stresses on the building possibly cracking the terra cotta. M R. B A R N ~ S: We were faced with that on a recent project in Oakland, where it was ex- pressed in IS of an inch drift per story. what depends entirely on the connection and it is quite practical, and the material itself is very adaptable to the proper connection for that. M R. F ~ s H E R: What is the effect of stack bond versus running bond in RBM? Mr. Dickey isn't on our pane] at the moment. Would he care to convenient on that front the floor? Someone said this morning they thought it would not have too much effect on the strength. M R. D ~ c ~ E Y: Yes. Normally the engi- neers just don't like to fool; at tile stack boncI. It (loesn't look as strong, lent the tests show

that we shouldn't Took clown at stack bond, that we should be snore optimistic. Tests showed that reinforced stack bone! wouIcI be just as good as your design valuation but that your unreinforced running bond would be eight tinges as good, which wouIcT indicate an extremely 1ligl1 factor of safety in masonry. M R. F ~ s ~ E R: What is the relative cost of cut stone and clay brick-say a cost per cubic foot? What is the ~nini~nu~ thickness of stone paneling? Mr. McKnigllt? M R. ~ C K N ~ G H I: Well, Mr. Fishier, there are several things teat are contingent here. For one thing, freight rates, location of the job. But for the roost part, you have the source of brick near every metropolitan area in the country;. Whereas limestone is very limited as to its location in areas. With regard to that last question on tl~ick- ness of our panels, today we are working on two incises. They have been adapted ancT are being applier! now to the two-inch thickness. We flack it clown to one inch, but at the present tinge our specifications call for the two-inch thickness. MR. Fisher: Mr. Taylor and Mr. Monk, Las any research been done on tile prospect of reducing tee thickness of joints on S.G.F.T. I'n~ not sure just what this means without grinding on the job, especially clouble-faced partitions? Can you continent on the general problem, Mr. Taylor, of joint thickness ant] flow you look upon it in the future research? MR. TAYL OR: It is a very important problem, and the control of clay to an exact size is often difficult in solve of our clay procT- ucts. But in terms of some cloul~le-faced parti- tions, they are available in some places in this country in two colors. The surfaces are glazecT. Sucks units are available in certain tripes of manufacture units tociay. We do fee] that when we leave a lightweight aggregate that we . . wit] cone even closer to having that sense control size available in all of our clay; products. M R. F ~ s H E R: How creep floes the color stain penetrate limestone, and can it be ap- plie(1 on tile job? Mr. McKnight? M R. :~! C K N ~ G H T: ~ think, Mr. Fisher, that ~ answered that question a minute ago when ~ said as an average the stain can now penetrate to a point of 3/16 of an inch to a quarter of an inch, according to the density of a product. You have to understand tllat, witty tile process of taxis special spraying equip- n~ent, you can put the stain into the stone with an absorption point where it will last for ~ 5 or 20 years. But you also have to take into consideration that stone is a natural product anc! will vary maybe son~etin~es within four or five feet running length. But ~ ant speaking now of tile average, and we wit] say it is 3/16 of an inch as the average and is good without any noticeable fading for 15 years. M R. ~ ~ s H E R: What are the limitations in the use of I~ighly-colorecl and figured ~nar- bles for very thin stabs? Mr. Ilowe? M R. H 0 w E: Well, of course up to this tilde we have used generally what we call the sound Garlic. But stuclics are going on, ancT T awn sure in the clays to come we wit] finch ways to perfect nature's shortcomings to use the colorcc! marble very successfully. M R. F ~ s H E R: Tllis is in connection with granite ancT marble research. How are the marble panels attached to tile buiTcling frame to prevent moisture pcnctration, to per- ~nit structural cleflection, but to be safe in earthquakes? Mr. Howe? Ma. HOWE: ~ clon't believe that ~ will attempt to answer that, sir. Of course on the west coast the present requirement is that tile n~arble panel, as an orclinar-y veneer, is joined 91

to the structural wall. I'm not experienced with this earthquake question. M R. F ~ s H E R: Mr. Barnes, what type of material is used for the intermediate or false joints in your panel? How was a satisfactory bond effected? MR. BARNES: The jointing mortar, ~ presume, is what is referred to, between the various elements of ceramic veneer in the one panel; ant] that is a rather dense jointing mortar application, approximately one to three, with one quarter part lime and a small amount of ammonium stearate added. What was the other part of that question? MR. F~sHER: Well, it's justthe same question, how is the satisfactory bond effected? assume the material achieves that. M R. B A R N E s: Yes, it will. if tile bone] material is well dampened, there is no problem on the bond. M R. F ~ s H E R: Mr. McKnight, are these penetrating stains inorganic colors? M R. M c K N ~ G H T : Yes, they are. These stains have been cleveloped not through our own laboratory anc] engineering abilities or facilities, but we have gone to some of the major chemical companies throughout the United States, told them what we were after, told them what the potential was, and they in turn worked with us in this coordinated effort in developing the stain. As a matter of fact, soda`; has been the first tinge a member of the Institute has released then; and the specifications preparer! for them will be distributed to the construction indus- try in the near future. M R . F ~ s I! E R: Mr. Taylor, your insti- tute has in the past frowned on silicones as a surface water-repellent treatment for brick, 92 etc., presumably because of suppression of efflorescence and hence promotion of spelling. T.s the Institute still committe.`l In that nosi M R. TA Y ~ O R: ~ have had experience with silicones and a knowlecige of them for a very long tinge. In fact one of my best per- sonal friends, probably, is the inventor and original developer of silicones; and ]: ant the first to admit that they wit} stop penetration of water through certain size pores and with a breathing action remaining. But they will not span, necessarily, cracks of more than a certain size, nor will they close up joint mortar cracked by erosion or other types of defects, unless the wall is first tuckpointed. I spoke about some of the danger of efflorescence due to interior water entering the wall from other sources. We leave firm proof and we have a building to point to in which silicone was put on it to cure the leaking condition that existed, without first putting the building into good masonry repair. And more than half the brick in that building have spelled. There are slabs a half-incl~ thick around the base of the build- ing. And silicone applied properly; wiT1 do a good job with masonry where special condi- tions make it necessary to use it. But T would hate to be the guy that put silicones on a building, made the decision to do it, and have to pick up the tab for rebuilding the building. And that is why we take that position. At one tinge our industry even considered supplying and furnishing contractors with silicone that we'd mix in our own plants. But we had to abandon that. It happens that, when soluble salts in the brick or mortar are dissolved, that solution of salt moves to the surface like normal water, only it is carrying efflorescence salts. When it reaches the silicone, it can moire no further, so evaporation of the liquid takes place at this point, because the surface is porous and crystal pressure develops which

can be as much as 4,000 or 5,000 psi locally or cause splitting of the brick itself. M R . F ~ s H E R: Mr. McKnight, do your through-wall pane} tests indicate that the use of Tectun~ insulation board, as the back-up for your exterior stone panels, afforcIs sufficient water resistance to repel driving water surface penetration front rain storms? MR. MeK~cHT: We have run tests on this natural stone facing utilizing a number of welI-known insulating n~aterials. The use of Tectun~ for a complete through-wall panel is, however, still in the testing stage. We have not as vet officialIv released such a wall for J J recommended use, but anticipate cloing so in the very near future. My picture of a through-wall stone faced composite was not Tectun~ but fount glass nanufacturecT by Pittsburgh Corning Corpora- tion. The many tests we have run for thin natural stone wall panels in combination with insula- tion n~eclia have successfully passed our labora- tory requirements. The U factor has been highly satisfactory. It should be noted that the insulation part of the unit assumes no structural function. It is, rather, a ~nediun~ to which natural stone facing or possibly a natural aggregate composite can be bonded. The other type of pane] which we have re leased will probably mostly be used in the cona- mercial field. On this panel we apply several thin stone pieces to a single sheet of Tectun~. In this manner we can construct a thin, stone-faced panel of aIn~ost any reasonable size. We are negating use of this development on a large shopping center at Indianapolis. The panels we use there are lL0' high and 30" wide ant} consist of 2" of limestone n~echani- cally fastened to 7" of Tectun~. The masons working with this new material for the first tinge anywhere achieve a setting rate of ap- proximately 1,700 square feet per day. This is not a complete through-wall. But the con~- bination of natural stone and insulation re- duces the wall weight in addition to providing a high insulation value, low cost, and sheerly erection. The panels are anchored into the back-up of structural steel with strap anchors and clowels. This type of construction is highly practical ant] may be adapted to many (resigns. M R. S I L L I N G: ~ think one of the most interesting things about these sessions that I have always found tremendously impressive, and that has impressed people front other countries who visit technical sessions in Ameri- ca, is to find the wheels within wheels. And while they may respectively rub abrasively against each other, T invite you to remember that they also do interlock; and T think that is a very interesting commentary on industry and private enterprise in America. 93

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