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Modern Masonry: Natural Stone and Clay Products (1956)

Chapter:II. Technology of Building With Masonry

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Suggested Citation:"II. Technology of Building With Masonry." 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:"II. Technology of Building With Masonry." 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:"II. Technology of Building With Masonry." 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:"II. Technology of Building With Masonry." 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:"II. Technology of Building With Masonry." 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:"II. Technology of Building With Masonry." 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:"II. Technology of Building With Masonry." 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:"II. Technology of Building With Masonry." 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:"II. Technology of Building With Masonry." 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:"II. Technology of Building With Masonry." 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:"II. Technology of Building With Masonry." 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:"II. Technology of Building With Masonry." 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:"II. Technology of Building With Masonry." 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:"II. Technology of Building With Masonry." 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:"II. Technology of Building With Masonry." 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:"II. Technology of Building With Masonry." 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:"II. Technology of Building With Masonry." 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:"II. Technology of Building With Masonry." 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:"II. Technology of Building With Masonry." 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:"II. Technology of Building With Masonry." 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:"II. Technology of Building With Masonry." 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:"II. Technology of Building With Masonry." 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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P A R T T W O PRESIDING CHAIRMAN John Knox Shear Technology of Building With Masonry M R. S H ~ A R: In this second session we turn our attention to the sub- ject of technology of building with masonry. Having started on an aesthetic basis, which ~ must say ~ commend, we must nevertheless move quickly into things equally basic but in another dimension. 29

Or:

Reinforced Brick Masonry R . ) O H N K N O ~ S H E A R: The tech~ol- ogy of buiZ3ing with masonry presents us with two men, an engineer and an architect, both coming out of backgrounds of broad experi- ence. Our first speaker, Mr. Walter L. Dickey, has had a broad background, which has pre- pared him for his discussion today. Mr. Dickey has worked at it actively and practicalZy, and has for many years rzow worked at it in the theoretical realm as an engineer. He is the chief structural engineer for the Bechtel Cor THIS is a description and discussion of the combining of modern reinforcing techniques with ancient and venerable brickwork, to solve problems of modern architectural expression and construction. The subject of Reinforcect Grouted Brick Masonry is one that is noted to tie into almost Walter L. Dickey Bechtel Corporation, San Francisco, Calif. poration. He is a civil engineering graduate of the GaZifornia :Institute of Technology and worked as a bricklayer whiZe doing graduate work on masonry structures. Mr. Dickey is a member of the American Society of Civil Engineers, the American Standards Association Masonry Committee the Structural Engineers Association of CaZi- fornia' the Pacific Coast BuiZ6ing Officials Conference and the American Ordinance Association. all the other topics of this conference. it provides flexibility in architectural design to achieve effectively the `'Aesthetic De- n~ancls of Contemporary Architecture," in- cluding n~inimizing the norn~ally great need for "era cl; filllers." It provides for combinations of "Colors and Textures" in almost anv type J ~ 31

of pattern that might be desired. It provicles for the achievement of "Modular Design," even the mixture of different modular systems within the same wall. :[t provicles for aIn~ost any 'Veneer" surfacing desired. It has been used in lieu of "applied veneer" in many instances. In so using it, the "Veneer ancT Face-bonded walls' would be homogenized with the struc- ture. The "TLern~al Performances is excellent. "Ceramic Veneer" can be used in this type construction. Also there have been instances in which "Natural Stone" was used as one wythe of the Reinforced Grouted Masonry. "Marble and Granite" night have been used although ~ do not know of specific instances. "Brick anc! Tile Research" has been conductecT extensively evaluating this type of construc- tion as well as providing information that can be used in unreinforced masonry. "In-the- wall Costs" are relatively goocT, and "Main- tenance of Industrial and Public Buildings" is minimized by this type of construction. :Et has been used in "Residential Design" with striking results ancT is effective in construction to provide not only curtains but also structural shear elements. It has been used on "Hospi- tals" such as the large Veterans Hospital just outside of Los Angeles at SepuIveda. :[t has not only been used in "Schools" but the Cali- fornia State Division of Architecture, responsi- ble for the design and construction of safe school buildings, was one of the leading or- ganizations in the initial development of the technique. ~ So it touches the many facets of a Modern Masonry Conference. AUTHOR s COMBINATION OF PRACTICE ran AND 1 HEORY The author's early experience was on con struction jobs as bricklayer laborer, hod carrier, brick layer, and brick layer foreman, primarily 32 on brick and tile walls, partitions, etc. The- oretical training was at the California Institute of Tecl~nology with graduate work, particularly in masonry structures. Since then experience was as structural engineer in private practice ancT structural engineer for the power division of Bechte] Corporation. It was in the latter capacity that there was the responsibility for the design of one of the largest brick builctings in the western area, a power plant some 800 feet long, 90 feet high and 400 feet wide. There were of course many other similarly in- teresting responsibilities, in the tremendous and widespreacT activities of Bechte! Corpora- tion. The above theoretical and engineering train- ing was valuable, but in design the practical experience was of even more value and aid in visualizing the problen~s of combining brick, mortar, grout and reinforcing into a 1~o~no- geneous structural element. The problems of design are no snore complex than design of reinforced concrete, but details of assembly sonnetizes tax the experience and practical ingenuity of the (resigner. WHAT [S RBM AND RGBM? The terms RBM~an(1 RGBM are abbrevia- tions of "Reinforced Brick Masonry" and "Reinforced Grouted Brick Masonry.', These should be definecl of course, since they are the subject of this paper. RGBM for some time referred to the reinforced grouted world that was cleveloped as a new method of construc- tion, and which became most generally popu- lar and effective. it consists of wythes of ma- sonry with grout poured between, i.e. a grout collar joint to provide for reinforcing, to tie the wythes together, and to form a weather barrier. There are other founts of reinforced masonry but this is presently the most effec- tive.... The rather clumsy term RGBM is now being dropped for the more euphonious RBM.

RBM is now being usecT as the generic terns for all reinforced brick masonry, wheth- er of the more popular grouted type, or the type with reinforcing in bee] joints, or in filler] cells or holes in the brick units, as will be dis- cussec! later. Frown an architect's standpoint, RBM seems to offer the designer greater flexibility in treat- n~ent ancT use of finisher] materials than any other comparable material or method. There is little limitation in selection of masonry materials, of patterns, of types, of sizes, etc. The choice is greater even than in unreinforced masonry. In adclition the finish surface or material is not applied merely as a skin or covering, it serves as part of the structure as well. It can be said that the finish becomes an active loacI-carrying participant rather than a passive Toacl, or burden. It is a mystery why so little is known about the use of this n~ethoc! except in the area in which it was initially cle- veloped. HISTORY RBM was reported to have been user] 140 Years ago in Englanc! ancI later in France and in TncTia. The author's first personal experience with reinforced brickwor]; was in 1911 on the construction of the State Hospital at Agnew. The reinforcing consisted of flat steed straps in the bed joints with notches or holes for vertical bars. The installation was not well re- garclecT by the masons, their felt tint "they had built the Pyran~icis without steel and steed was not necessary." However, while rein- forcen~ent has been used for a long tinge ancI sometimes rather haphazarcIly, to strengthen n~asonr,v, reinforced brick masonry in the modern sense is a relatively new construction requiring new design procedures and new con- struction n~ethocis. In the past 20 years espe- ciaTly these have been developed from experi- mental investigations ancT observations of con- struction of hundreds of buildings uncler orclinar,v vertical Toacis, anc! uncler the influ- ence of earthquakes. The trained and practical observation as well as the Iaborator,v work has confirn~ec! the soundness of tile scheme. LONG BEACH EARTHQUAKE RBM was developed ant! has experienced its greatest use and improvement in the Southern California area. It was there that the Long Beach quake of 1933 shook clown the cheaply built, poorly designecl, loosely tied, boom built, brick structures. Brick were salvagecT and cleaned front the debris be; the simple expedient of sweeping off tile loose, powdery mortar crust. It was said at the tinge tint the purpose of the mortar nest have been to "keep the brick apart" rather than to bond then together. There was an example of a stack of brick on a pallet adjacent to a collapsed brick structure. The pile was still unclisturbecT anc] standing relatively true, not having mortar to keep the brick apart, while the brick building was a pile of debris sin~ilar to the photo below of the church in Bakersfield. ~,~ ,,, ~ ~ ~ ~ · ,,, ~ ~ ~ T~ ~ ~ ~ ~ ~ : ~ OLD BRICK CHURCH AFTER BAKERSFIELD EARTHQUAKE OF 1952 The old church in the fore:,round' built with old brick masonry desi:,n methods' was completely destroyed. The new annex in the background' built of 8" RBM' is unharmed. 33

Some of the brick structures that were clef Polished by the Long Beach quake were iden tical to many of the brick structures now built in the East (since the last big earthquake occurred in the area ~ . The first quake, for ninny, will probably be the last. We do not predict a quake soon, but the records, as shown on the seismic chart, show quakes have oc- currecT here in the past. DESTRUCTIVE AND NEAR DESTRUCTIVE EARTHQUAKES OF THE U. S. THROUGH 1950 While the greatest number of earthquakes has occurred in the West' particularly California, some of the largest on record have occurred in the Eastern area. Since the builctings referred to had not been designed to resist any lateral force the factor of safety against lateral force might be FS ~ O-- O so Lence the collapse. The buildings that suffered worst as a group were the school buildings. These hac] certain unclesirable characteristics in con non. Tilers was excessive, massive, ornate gingerbread! "embellishment" arounc! the top. There were Digit winclow openings, in~posing top-heavy entrances, a minimum of structural material to back up the fancy facing, a n~inin~um of roof structure and detail connection-eEect of unclue emphasis of a competitive bidcling system inadequate inspection of the quality with resultant n~inin~u~n cement content, and low regard for workmanship. 34 The sight and Sensory of brick buildings collapsed as piles of debris was a factor that practically elin~inate(1 the popular pendant for brick production, especially perhaps since so much "used" brick was available in such good condition, unbroken and hardly stained. It was obvious then that a different type of construction nest be developecl. DEVELOPMENT OF RBM Recognizing the advantages of bricT; con- struction and the serious need for developing structures to resist quakes safely, the Southern California groups initiated active programs of engineering study. Mr. Harry Bolin was one of the aggressive and far-seeing engineers who cIid much to develop the scheme of grouted reinforced masonry; and to conduct tests which verified the soundness of the various factors He established facts where there hack been but theory before. One series of tests was especially interesting and valuable. It establiished that grout could, and should, be pourer] very wet, even "sloppy, ~ apparently violating the engineering concept of "water cement ratio.' The grout might be poured, with a W/C ratio to result in 1600 psi concrete, but due to the absorption of the brick ant] the subsequent curing effect, the grout core when actually tested couIcl develop 5000-6000 psi in 78 days. Also, when poured tllusly, the bond was extremely laigh. The first noteworthy exan~ple of that pro- gran~ was the Vermont Avenue School built in 1937. Many types of masonry were attempted special shapes were (leveloped The Grout Lock Brick and the Port Costa Key Brick shown in the sketches are two. The ~ne- chanical key to the brick is a desirable feature, elin~inating one of the hazards of poor world manship, namely poor bond. However, sinus

Scab forcing Is. 7 Z~Gro~f \ . / ~ . - 7 me, _ A ~ ~ , - _ comer ~ . dS"WALL CORNER CONSTRUCTION DETAI L ~ 124"s 134~ PI ER In: ~ if ~e,~forceo' fork AFROS L~ Is. ~ IS ~ ~ ~ ~7fl /f~c CO LU M N ~ BE AM 8 E A M BR [C K C O N STRU CTION PORT COSTA KEY BRICK GROUTED MASONRY Sketch at upper ri,,ht shows typical wall sec- tions constructed with special brick known as `-Groutlock'' brick. The beveled ed:,es of these units provide more space for both vertical and horizontal reinforcing' and give the impression of mechanical bond. Although such special shaped brick as shown here' on the Port Costa Key brick details' and L's and soaps used on the Vermont School have been developed in some areas for RBM, it can be designed and constructed with the conventional brick shapes and sizes found all over the country. Slcetcl~ at lower right illustrates various REM wall sections and thicknesses constructed with modular brick of conventional size. Variations are possible as brick sizes vary locally. In most cases the variation will be largely in the over-all wall thickness when brick of different widths are used. Thickness of vertical or horizontal joints is determined by the size of reinforcing bars used. A minimum of ]/4 in. clearance should be maintained between the bars and the masonry units except that No. 2 (~/4 in.) liars may lie used in ]/2 in. joints. 1 \ 3/~. ~ ~ 2^'0.C. ~OQ':O~TALLY - 19~0.C VLRTICALLY PLAN OF 7 ~ WALL BLA M bR,CK Grabs ~lLrCK TYPICAL GROUTLOCK BRICK CONSTRUCTION >40~1~AL SIZE OF bR\C~ ASSU "CD A5 23 ~4 ~ d' ' ~W In' four rl`L PtA CRAV[L \ GQOLUT rail ~ -I ~ ~ 1' l l >' For arl~roQc` - c'4r NIL ~ '~'-1 ~'CLlAQAbCt ~ Rt~rORCC"C~7 i ~ ALL' -I ~ afar ALTER,4~` POSITION. ~ or HORIZONTAL b^QS 1 ~F7- (THESC 64~5T BL.. 2 ~,r Jolt 15 'I') ~ . ~ . .,1 1 | ;~' ~. rod Q~l~ro~cc~c~T I'd- Ail 3A'1. ~\'l~ (LtA4A>`C£ TO 411NtO4Ct - C - T 5' WALL ; . ~ l . . ' . //~/ f ~ ~ -~. ~ ~ ~r ~ ~ ~ . Amp. . j HA' loll 5''- yell a/ ~ , . 1 , | 13'6 WALL ; |- -- - - ~; ~1~1 ~11~1~ ;~h 1'i 34 anti 3~ I L 12 /s WALL i VARIOUS RBM WALL SECTIONS WITH CONVENTIONAL SIZE BRICK 35

taneousT:, research in mortar and grout had disclosed the fact that bond between brick and mortar couIc3 be so good as to be better than tile strength of the material, under prop- er conditions. Therefore there was no need for special sllapes, ordinary common brick of any shape and size would clot The only special con- sicleration was good workmanship, i.e., clean moist brick, good plastic cement mortar, sloppy wet cen~ent grout. Other masonry units such as tile, stone, concrete block. etc., could serve. PRESENT RBM DATA There is a wealth of material publishec! on RBM but two publications are especially rec- on~n~encled as covering flee subject quite thor- oughly and in considerable detail. One is the "Technical Notes on Brick and Tile," Struc- tural Clay Products Institute, Volume I, No. I, 7, 3' and 4. Another is the very excellent book, "Reinforced Brick Masonry and Lateral: Force Design," by Mr. Harr,v C. Plun~mer of the Structural Clay Products Institute and Mr. John A. Blume, one of the leading structural engineers of the west. A good guide to the design of RBM, in the western areas especially, is the Uniform Building Code developer! by the International Conference of Building Officials. One of our Conference Con~n~ittees also prepared a book- let as a practical aid to inspectors of RBM, "Reinforced Grouted Brick Masonry Field Inspectors Handbook." These describe construction procedures and some effective methods to aid in accon~plish- ing teens. They emphasize the importance of good workmanship and continuous inspection to achieve it. The importance of the inspection is to be noted in the different values of design strength which are permitted in the Design Tables of the UBC. The clesign strength permitted is considerably higher for continuously inspected structures than for those not inspected. 36 TYPES OF RBiM As mentioned before there are many edec- tive types of Reinforced Brick Masonry. Some of these are listed below. The item in common is the use of masonry elements and reinforcing boncled together by a cen~entitious material' generally cement mortar an(1 grout. Stone Masonry Stones set in mortar Cavity NVall lMasonr: Space provided between wythes Reinforced Hollow Unit Masonry The units contain hollow spaces, and reinforcing may be in joints or in filled cells. Reinforce(1 Solid Masonry Solid Masonry with the bars in the becT joint or between soaps' for example. (Includes SCR 8z Brix Blox, etc.: Reinforced Groutec! Masonry Wythes bonded together with grout collar joint between. Composite Construction Might be similar to reinforced grouted masonry, with hollow units in one wythe and solid in another. I~nprovec] use of mortar was developed in the search for adequate reinforcing methods. The mortar of the new RBM is almost as unique a feature as is the reinforcing, ant! is a feature that insures the action of RBM as a homogeneous element. Two of the above, Composite, referred to frequently, and SCR are describe(1 in noose detail. The Bricl: Block, a form of reinforce soli(1 masonry, is mentioned briefly. There have been quite extensive tests on many of the aspects of the above types, too numerous to mention in this paper other than merely in passing, and to emphasize that they verify the theories.

COXIPOS3[TE GROUTED MASONRY 800. /'SC/i?4C~__~ CONSTRUCTION /; ~ --- ~ :~ - Tllis may be of many types' and one, tile combination of structural glazed tile ancI co~n- n~on brick. is described here as an example. This type was used in a plant in which there were laboratory, ofI;ce, and storage rooms. Along one side wall there was an outer finish face, which was entirely of a Norman unit stretcher bond. The inner wythe in the storage area was a bunko brick, economical of n~ate- rial and labor. The laboratory was formed by intersecting walIs of reinforced hollow glazed tile and by having the interior wythes of the exterior wall co~nposec] of glazer! tile, bondec] to the grout collar similar to the brick. Then in tee office space adjacent in this same ex- terior wall, the interior wythe was a buff face brick in lieu of the Norman, jumbo or glazer:] tile. That particular wall was an example, to a sn~all clegree, of the freedom and functional expression that might be achieved with REM. The (resign of such composite shapes re- quires a thorough visualization of stress paths, requiring that one cleIve into the higher orders of witchcraft. Recognizing the uncertainties, the author participated in some tests which were neatly on reinforced beans which verified nanny items rather satisfactorily. Results of the tests of clay tile beans with their complex interior shapes are indicates] on the chart. The chart (right above) indicates that n~a- sonry, in stack bond, complies with the design values permitted. It also emphasizes that ~na- sonry is a good n~aterial on its own, without reinforcing. It indicates also the comparative value of stack vs. running bond. Since the stack bond performed as well as design values wouIc] require, we should note that the running bond is so much better than the stack bond, rather than stating that the stack bond is so much worse than the running bond. In other words: 600, 500 . ` 400. 3 Boo . 200, O O 50 /' ~\ ["'a- ~ ~ ~ ~ ~ ~0~0 SHOOTS' / / -I ~ ,. T~ - SICK r~ TESTS OF STRUCTURAL CLAY TILE The type tested is shown as above. The three arrows on Design Curve show Calculated values for ``uninspected'', ``inspected,?, ~`ultimate.~' This illustrates' not how poor stack Lund is' but how excellent is masonry. "The glass is half full!" not "the glass is half empty!" The sections of composite brick and tile con- struction iTIustratecT on next page are for fur- ther clarification of the type. The test ~netho(1 which was used to check the increase of strength achieved by the grout as poured between the brick is shown in the sketch below. Grout should be poured into place very wet to make thorough intimate bond with tile TYPICAL MASONRY TEST PRISM Well oiled, non- absorbent /: end p I ates. ,: Typicai for job. it/ / ~ Swell oiled, non-absorbent base plate. tA OQTAQ ~^,`~:~ | GROUT 37

masonry and reinforcing. Tile porous volume of masonry then sucks the water from the grout core leaving it with an excellent. edective water cement ratio. The tests showed that the grout samples developed 1600 psi in 78 <lays. However else grout core. tal;en frown the ma- sonry enclosure c:Tevelopec! front 5000 to 6000 ps~. SCR SCR is a through wall type of construction sin~ilar to partition tile or concrete block. The ~nasonrv units are of cIav like cannon brick ~ J but are the full wicith of the partition for a single wvtLe wall. Horizontal reinforcing in the form of senate bars or i'1adder" reinforcing can be placed very easily in the mortar joints. Vertical reinforcing can be provided but not with tee sane ease. Structural clay file has greater flexibility in the placing of reinforcing, similar to the more conventional reinforced hollow masonry, or concrete block work. Both SCR and tile den~- onstrate the efficiency of providing an archi- tectural finish material which serves simul- taneously as tile structural element. These types of construction are especially well suited for economical curtain wall function, or parti- tions for space division. TI~ev resist lateral forces of wincT or eartL- quake and receive stability frown the fact that they are generally spanning horizontally be- tween relatively closely spaced supports, such as front column to column or between inter- sections of walls. These intersections generally occur with adequate frequency so that no spe- cial structural frame need be added. An ordi- nary; wall is laid and no special provision need be Oracle for it to be structurally satisfactory. If necessary however, elements such as rein- forced masonry pilasters may be added. They 38 can be quite economical if properly detailed so there is minimum interruption of the ma- son's work. They may be exterior pilasters or may be reinforcing bars in the wall between soaps. REINFORCED GROUTED BRICK & TILE CONSTRUCTION Typical Vertical Wall Section Vertical Section at Pilaster An example of the effective use of SCR is illustrated in a school building plan and science developed by the Structural Clay Products Research Foundation and entitIec] "SCR school clesign concept." This concept was developed for areas not subject to the hazards of earthquake and is quite econon~ical. "First SCR Concept School goes for $6. /1 per square foot," the journal Masonry Builcl- ing stated recently. Tile "BoonviTTe-Boone Township School' plan for masonry building costs less tIlan $10 per square foot. It features partitions lair! out with returns or intersections. In this manner the SCR concept could be revised slightly to acicl reinforcing for earthquake, tornado anal blast resistance. It would merely be necessary, for exan~ple, to provide that the wall portions span easily between vertical elements, which can be re- turns, pilasters, or "soap" reinforced elen~ents, and the tops of the vertically reinforced ele- n~ents supported laterally by tile roof structure.

REM AD\TANTAGES Savings In Structural Steel Support Savings In Steel Reinforcing It is recognized that masonry shows less shrinkage cracking than concrete ant] therefore customarily less temperature reinforcing is re- quired for masonry walls than for concrete walls. In addition unreinforced rnasonr,v panels can be included between reinforced portions for even greater savings. These savings in rein- forcing steel night be very important, espe- cially (luring tinges of acute steel shortages. In some instances the supporting structure can be incorporated in flee masonry with no acldi- tional reinforcing. The table below shows tile comparison of temperature steel required in masonry walls of various thicknesses as contoured to that re- quirecT for reinforced concrete walls. Concrete requires .0025 x area each way, but masonry .007 i; area, or .001 ~ area if divicled equally vertically anc! horizontally, i.e. concrete re- quires 7~/' tinges as much as n~asonr~ NIININIUM NVALL REINFORCING ( UBC ) REINFORCED BRICK Wall As/ft. ~bars & Weight Weight (to) I ea. way spcg psf i psf 6" 8' 1 10" 1 .120 .072 ~ ~9 ~18 1 REV 1 .096 ~6 ~@,13 ~11 ~lv .144 ~ W;~VR~) 34~?,16 Advantage can be taken of tile bigly com- pressive strength of masonry to carry vertical Toads eRectively within the wall. Then, if there is other consideration, SUCH as lateral force or moment in~pose(l, special reinforcing can be added. In this way many building types can be constructed without requirement for support- ing structural steel. E CONOMY OF REINFORCING AND LAYING Economy of placemerzt is effected since tile reinforcing can be placed easily and econo~ni- cally by tile masons as desired. Workmanship is important in all masonry work, but some of tile uncertainty is removed by tile pouring of the grout. It provides a weather barrier. It bonds tile wytiles securely together, it fills the portions of bed joint that may not Lave been filled full, it fills the back REINFORCED CONCRETE l l bars & ~As/ft. ~Wall spcg ea. way (~) 1 ~.18 6" 1.22 ~ ~@,8 ~(~13 .65 . ~- 1.62 ~@J5~' .24 ~ 34@,10 I . _ 8" .81 ~2.04 ~8 .30 10" ~12 1 _ ~_ ~I .98 1 2.431 ~6~' ~(7,10 .36 1 12" 39

of the head joints providing good bond in tee event the mason Pact not used full shoved joints. In fact some careful workmen leave the inside edges of the joint open so the grout will flow in and develop good mechanical bond in addition to adhesion. When RGBM was ini- tiated into the Utah area in a power plant program, it was necessary for the author to spend a few days indoctrinating the masons. T ~ ~ r ~ mere are some exan~ples ot what tl~e masons were told: "Don't spread such a full bed- it squeezes out into the grout space. "Put more water in the grout so it is sloppy and pours easier. "Don't put so much mortar on the heac! joints, it's better if the back edge is not full than for mortar to extrucle or drop into grout space. `'Don't furrow the bed-merely swipe it. "Don't wet the brick too notch, they won't dry up the grout core. "Don't put those headers across do it as shown in the drawings. 'Don't put that angle over the opening, you don't need it and it will rust. "PucIdle the grout quick while it is still wet- don't wait. "Don't bother to tie the bars, you jiggle then too eunuch, just lay then in." After a short while one of the contractor's forenoon said: "But those are all things that will help us save money; we have a Jump sun contract!" After teat he was very cooperative and helpful ant] Oracle constructive suggestions himself. E CONOMY OF REINFORCING WALLS It is recognized that steel reinforcing antis strengths to walls, particularly with regard to buckling tendencies. This is recognized to a certain degree in the Uniform Building Cocle where the H/D ratio permitted for unrein- forced bearing walls is 20, but for reinforced walls the H/D may safeIv be increased to 25. 40 The additional strength is also recognized in 'non-bearing walls' in which the limitation for H/D is Z0 for unreinforced walls but is 30 for reinforced walls. An exan~ple of the practical result of this additional value wouIc! be for a story height of 20 feet. Obviously it would be necessary to use a wall thickness of 12 inches for unrein- forcecT n~asonr,:: but the grouted rcinforcecT ~na- sonry couIcT be ~ inches thin! The unreinforced wall would require 50:O snore brick and labor and would add 50 ~ snore weight to be carried by the supporting structure. The foundation would 1lave to sup- port the additional wall weight' the additional structure weight and its own consequent acidi- tional weight. Also, of course, by a little exercise of in~agi- nation it Night be possible to eliminate much of the supporting structure, incorporating it within the reinforcing and strength of the REM. BOND BEA~r The "Bond Bean" is another element that can be built into the masonry effectively. The masons build to the bond bean area and con- tinue right on through, placing the reinforcing as they go. This is as opposed to cletailLs which too frequently require that the masons stop when they cone to the bond bean area. Then carpenters cone in to build forms, steed need to place reinforcing, concrete men to pour the cleans, carpenters to strip and the masons to return and continue with the briclkworl; all of which makes the hair of the superintendent charged with the coordination and cost of con- struction turn grey. Bond beans of REM were used efl ec- t~velv; on the P. G. & E. Contra Costa Steam Plant, a building some 800' long, 450' wide ancT 90' high. (Described in greater cletai] in ASCE Separate No. 347, No. 540 and an arti- cle in Engineering News-Record, July; 5, 1951.) Tllis plant was designed for a higher

assumed seismic coefficient than generally con sidered adequate. In spite of the high design lateral force, and the 27-foot spans, the bond beans were of REM, as were tile lligl;l ele- sonry units. relents between tile "slotted" winclows. Allis enabled tee masonry construction to proceed economically without interruption. As mentioned before, this brick building is some 800' long and it is to be noted that there are no visible cracks in the front, rear, or inter ~ncdiate walls, aTtl~ougl~ there are cracks in the concrete base portion at about 9 foot centers. DESIGN The structural design theory for REM is identical to the design theory for reinforced concrete, except teat certain different nu~neri- cal values are involvecI. Although the clesign is so similar to our familiar reinforced concrete design, certain portions are discussed here for greater clarity. For example the basic assun~p- tions are: I. The materials are stressec] within the elastic limits so Hooke's Law applies, i.e., "stress proportional to strain." 7. Plane sections before bending are assumed to remain plane after benching. 3. Tension in the masonry is neglected (ex- cept for unreinforced masonry portions). 4. Bond is developec] between stecT and ~na On tile basis of these assumptions, which result in rather conservative structures, tile following approximate forn~ula may be used. M (steel) /s A8f,~ M (masonry) fix by' 6 Formulae can be derived and set up in form similar to those for concrete for "exact" solu- tions' e. g., clb' M/K, and saline procedures foIlowect including: V l.:L - bj] it- ojU Although the design of RBM is basically identical to tile design of reinforced concrete' the actual RBM cletaiTs Night tax the in- genuity of some designers. He does not 1lave quite tile freedom of placen~ent that he 1las in reinforced concrete. He must recognize arid visualize flow the structure will be built by bricklayers placing nodular units in a definite pattern. He always keeps in Nina, of course, tile basic factor of tying all parts of tile struc- ture together. As in otter architectural design, _ TABLE OF STRESSES (Assume form & f'c = 2000 psi) Types Of Stress | RBM Compressed Flexural Axial Bearing Shear no web reinf. Shear with web reinf. Bond, Def. bars Modulus of Elasticity Steel, tension fin = .33 f m 670 fm = .16 f m 320 fm = 25 f rr 500 vm 50 v 150 um = 160 Eon = 1000 f'm 18,000 psi Reinforced Concrete f =.45900 fc=.18360 fc=.25500 vc= .0360 v =.12240 uc=.lO200 Em= 1000 8,000 psi 41

it is imperative that tile designer keep clearly in ninth and execute completely a compre- hensive scheme of franking to resist the loads. For example. a load on a slab is carried to beans which are carried to girders Chicle are carried on columns, which are carried by foun- dation pads. All elements of that scheme must be satis- factorilv checked that no one little link in the chain will be overstressed, or overlooked. It Piglet be e~npl~asized here that the amount of material is not nearly as important as its proper placement. As on Marilyn Monroe, the amount of material is not as important as is the proper distribution in the right places. Another item of growing popular concern is consideration of blast resistant design. The primary consideration in masonry structures is ease of placement of reinforcing to resist the very high loacling assumptions, and free- clo~n in providing for tying all parts into an in- tegral structure, one that will 'hang together." An RBM wall designecl for blast resistance is sl~own in the figure below. As can be seen this wall is heavily reinforced and "soaps?, or split brick are used so the reinforcing may be placed nearer tile outside surfaces. ~.. A, . . ~ VERTICAL LObIGIlUDIWAL SECTION AND ELEVATION 2 ~ 0 o c . RBM BLAST RESISTANT WALL ~2 It Night be well for the structural designer of any plant to check our financial tax struc- ture and the benefits of fast ' write-off" that may be utilized for plants designed to resist atomic blast. USES 0E RB)/] Following are some examples of the freeclon~ of expression in this n~ecliu~n. The list is mere, to show songs different types of examples of structures. Some are economical solutions to simple problems and some are to illustrate and e~npl~asize the principle that one need not be bound to simple rectangles when building with bricl:. Some are simple conventional solutions and some are unusual. Proof of the a(laptabiTity of RBM would be shown by tee long list of structures in which that type of construction has been successfulIv J J usec! during the past 30 or snore years. Space does not permit listing then but they include large industrial and co~nn~ercial builclings (warehouses, power plants, stores and facto- ries ), public schools, college and university l~uiT(lings, hospitals, VA Hospital in Los An- geles, churches, public buildings, resiclential buildings and such special structures as stor- age bins (circular or rectangular), highway bridges, bleachers, etc. Even in structures not requiring design against lateral forces, RBM lintels are being user} Core and more by many architectural and engineering offices. Also bear- ing walls are reinforced because of the econ- on~v of masonry material and labor. A complete listing of all structures utilizing RBM would show its versatility and accept- ance by engineers anti architects. The sim#Ze ZinteZ can be eFectiveIv built witty reinforcing imbedded in the joint. This is as opposed to the cost and inconvenience of steed lintels and shelf angles. Not only is the RBM J lintel less costIv than structural steel, but the hazard of corrosion with consequent cracking,

of masonry is reduced. In adclition REM elin~- inates the neec! for maintenance painting. Also fire hazard is reduced because the reinforc- ing of the IBM lintel has suitable anc] ade- quate cover for fire protection. An example of an unusual use of brick is shown in the photograph of the garden bench. it implicates a certain freeclon~ in the use of tee nasonr;; diFering front the conventional brick paving or brick walls. Due to its rather unbe- lievable shape (i.e. cantileverecT brick) it has presenter! a challenge and has been severely tested by groups of men at a stag barbecue. Alley ju~npecl up and clown on the outer edge to see if by singing ancT jumping in unison they couIcI break the brick cantilever seat. The only Manage so far was one skinned shin clue to a slight unsteadiness of one tester. GARDEN BENCH Originally the bench hac] been designed for the brick to be placed "flat", 2~/~" thick rather than 4" thick. Since the owner, Lowever, could not overcome his psychological block that brick is intended only for bearing and not for canti- lex;ers, he wouIc! rather have it heavier. This reaction is a senate example of the need for i~n- agination in design ant! for sound public eciu- cation in this matter. The best education of course is physical example, and we need n~ore Acorn derring-clot Another example of the eFective use of rein PALO ALTO CITY HALL LOBBY forced brick is the curved wall at the encl of the Palo Alto City Hall lobby. This is a reinforced grouter! wall `'cantilevered" above a concrete floor, receiving no lateral support at the top, anc] over 10 feet high. However, by curving the wall we not only achieve a clesirecT dramatic efl ect in the lobby but provide stability similar to the stability cle~nonstrated in a serpentine single thickness brick wall on Thomas JefFer- son's estate, built in the 1700's. Proper use of shape is the factor notating Jefferson's serpen- tine wall so effective. CHIMNEYS CI~i~nneys can be constructed rather eco- no~nically of REM. Chimney design is dis- cussecl in excellent articles in the July and Au- gust issues of "Masonry Builder, and also in SCPT Technical Notes of April and March 1955, Vol. 6, No. 3 and No. 4. Another good design guicle, and one which inclucles not only stress due to wind and weight but also due to temperature, is the ACT Standarcl Specification 43

LIGHT STANDARD This effect is achieved by threading a con- crete prestressin~ rod through the draw holes of the brick. It illustrates a large and little ex- plored field. There have been some examples of ``stressed'' masonry like 'CStresscrete', which uses stressing rods in concrete block panels, but there has been no very great application of the principle to masonry. for Design of Reinforced Concrete Chimneys, ACT ;0~-54. Economy of seismic design is dis- cussec3 in Dr. Housner's paper published in ACT, 19;6. merely of draft consideration and stress but, due to our increasing concentration of in- dustry, of selecting the most economical con~- binations of height and top diameter (since top I.D. establishes flue gas clischarge velocity) for a desired reduction of the concentration of noxious flue gas discharge. Tile interrelated cost factors are, of course: Construction cost increase with height in- crease. Construction cost increase with top clian~- eter increase. Pumping or fan cost decrease with height increase. (Draft gain.) Pumping cost decrease with top diameter increase. Dilution gain with height increase and con- centration increase with top diameter increase. Given the solution to the above, frequently manacle more interesting ancT complex by earth- quake considerations, the engineer may find an economical solution in REM, especially in the lower stacks somewhere under 200'. Any desired diameter, thickness and taper of cliam- eter or thickness can be achieved easily. The more modern plants discharge gases at rela- tively low temperatures so separate linings to resist extremely high temperatures are not re- quired. Frequently the interior wythe can be constructed of hard burned clay brick. The va- riation in thickness that is required for great- est economy is easily achieved by varying the number of wythes and the thickness of the col- lar joint. A simplification of the running bone] was used effectively some time ago to provi(le for the variation in circumference, or length of course. Tile Cottons of the courses was started with some wedge shaped pieces and varying bed joints so that the courses were con- tinuous "spirals" round and round without need for cutting brick to maintain "bond" in The proper sizing of stacks is a problem, not tile coursing. Then to speed production a dou 44

REINFORCED BRICK WALL Strikino color and te.xt,~re. e{~.~.ts can be achieved by using,. different brick in a single wall. ble pitch "screw thread" was used. Two brick- layers could work simultaneously on a wythe, tee faster one of course catching up to tile slower one. The contest was obvious, up on a stage in full view of the entire project, and the production was quite high in quantity as in ele- vation. Some said that the "screw" bond ar- rangen~ent was quite appropriately named. C ONCLUSION \~:e Lave describect the details, advantages, and disadvantages of RBM. Although RBM was developed initially in the west to meet a need for an economical earthquake resistant construction, it has certain inherent qualities making it effective in any area. As a conse- quence it may make the use of masonry fea sible and more desirable than some other mate- rial in many instances. Furthermore no area is entirely free from earthquakes; some of the strongest known have occurred in the east. It nigllt therefore be well to take advantage of RBM's inherent safety factor. r n 0 sung up: RBM is the technique of laying exterior and interior wythes of masonry with a grout collar joint in which reinforcement is placed. It provides masonry surfaces of elements of (lifFerent heights, types and coursing, all incor- porated into a homogeneous structure. It has an adaptability and freedom of expres- sion which could be snore fully realized. Design theory is iclenticalL to reinforced con- crete design theory. 45

Validity of tile principles and tlleor~- slave been establisl~ed by test. It leas a tremendous factor of safety over per J witted clesign values. It is subject to seine typical masonry clisad- went vantages, namely, modular restrictions of size or placen~ent, and sensitivity to l~un~an work- ~nansl~ip. It is new ant! masons nest be trained in slightly different techniques. It leas several advantages, for instance: An ageless ancT warns beauty, wills intcrest- ing texture ancI pattern. ~ relatively low cost of placement. An elimination of certain Duncan equation factors. 46 low ~naintenancc cost. Excellent resistance to cracking and dider- ential settlement. finish wall that serves as a structural ele :Eligl~ ea Nil quake resistance. Good atomic blast resistance. Good wcatl~er resistance. Allis discussion will, ~ lope, help enrich the vocabulary of the architect and engineer who seeks full, free, uninhibited expression of Lois creative imagination as well as function. It may also provicle food for tl~ougllt for tl~ose Also seek econo~n~, better builcTings at lover cost.

Cavity, Veneer and Face-Beaded Walls M R S H ~ A R Our next shaker is Mr. Stalker O. Cain of the distinguished New York architectural jr?n of iMcKim. Mead ~ White, where he is a farther. Mr. Cain has a Bachelor of Architecture degree from Western Reserve University' a Master of Fine Arts fro no Prince- ton, and is a Fellow of the American Academy in Ronnie. A 1nenzber of the American Institute of Architects, he is on the Executive Commit OUR continuing experiences with Tow-cost dormitories led us to the cleveloprnent, to- gether with the firm of Severud-Elstad Krueger. and Edn~und J. Rappoli, builder, of the system known to many of you as the "edge- forn~" method of pre-cast concrete construc- tion. It involves the mass production of the vertical components of a building ~ exterior ;valIs, corridor walls and partitions) ancT link Walker 0. Cain 7\1cKi~n. Mead & N(hite. New York. N. Y. tee of the New York Chatter. He is also Vice President of the Architectural League of New York City and a Trustee of the American Academy in Ronnie. Fir. Cain's office has' over the past years, done some particular work in cavity wall con- structio1~, which he wiZ~ speak to you about. He has been asked as well to address himself to subjects of veneer ant! face-bon(le(1 walls. ing them by poured floor stabs. The structural design is such that columns and beans are virtually elin~inatecl frown those parts of the structure where the system is used; more con- ~entional construction being Finitely to rooms such as lounges and dining rooms requiring longer spans. Without dwelling on the techniques of mass production and the assembly of con~- 47

portents at this particular meeting, it can be sai<l that within the limits of problems to be solved, our system has proven to be a sheerly, closable, and economical solution to tile Tow- cost dormitory. Of greater interest here is tile developn~ent of an appropriate outer skin for the structural frame referred to above. Among its requirements were that it be (~) low in construction costs, (~) Tow in ~ainte- nancecosts, (3) clurable, (4) weather-resistant, ~ 5 ~ attractive in appearance. Another require- n~ent was that it have the characteristic of aging in an attractive manner. On many campuses the dormitory nicest furthermore re- late well to other materials of the existing campus buiTclings. Dealing as we were wits 'prefabrication" it was natural to consider skins macle of large factory-built pieces, neecting only to be raised anc! buttoned into place. At the period of our initial investigation, and continuing only slightly less so since, metal assemblies, (respite many advantages carried a cost penalty which in the end eliminated them frown the Tow-cost bracket. Other architects have confir~nec! this in their subsequent applications of our system. Our studies also showed that precast con- crete exterior panels, to meet cost limitations, hacI to be quite large. The problem here was not their weight or the erection difficulties. but their coefficient of expansion. Tn New England where most of these builcTings are located, the cTin~atic variances present serious problems for an`; material, especially the prob- lem of movement due to temperature changes. Further, the larger the unit, the greater the change of dimension. It cleveloped teat an economically large precast concrete exterior panel would cone and go enough to make it extremely cloubtfuT whether the joints wouicT hold. We finally founcT a solution to our problen~s in a 4" common brick skin, separated by 7" of air front tile structural frame, and tied to 48 it by metal anchors. Allis outer layer of brick was often carried on an extension of the 2nd floor stab and ran 3 stories up to an extension of the roof stab. The first story, often hous- ing the special rooms, was usually treated dif- ferently, with large glass areas, ancT walls sheathed witty special brick in patterns. We looked on this solution as a happy coincidence of an attractive, quality n~aterial anc: a low budget, not always an architect's lot. It should be n~entionecT teat taxis applica- tion of brick cle~nands a reasonably high stancI- arcT of performance by tile bricklayers. Main- taining the essential 2" air space free of fallen mortar was accomplished by hanging wooden lath in tile void to catch the spillage. The metal ties were ideal collecting points for fallen mortar ancT wouicI, if strict supervision were relaxecI, produce "bridges" or conduits for moisture to follow into the walls. Weep holes at the base of the wall were proviclecI and they too hac! to be kept clear of mortar. Other cle- taiTs, however, were so familiar and tested by time that over-all economies produced a quite satisfactory application of this material. The application of stone to the surfaces of buildings has for centuries posed technical as well as philosophic-aesthetic problems for the architect. At meetings such as this we hear something of each. The former are the most tangible and perhaps the easiest to solve; the latter, having as they do the component of tinge, seen never to be solved for Inore than a n~o~nent. Thev do have in cannon the fact J that veneer and face-bonded construction is essentially one of sheathing less precious ma- terial with snore precious n~aterial a technical propylene in economy and an aesthetic one in expression. By definition we refer to face-bonded walls as those in which 70% or snore of the exposeclL surface is bonded to its backing. Anything less is generally considered veneer. Historically, both are of ancient lineage and appear con

stantly throughout construction history. When we read that Augustus "found Blonde a city of brick and left it a city of marble," we acknowI- edge it a feat even in marble veneer. Although the technique of applying stone sheathing has changer! remarkably little front that tinge to this, there has been a notable change in de- sign and construction of the building frame itself. Where the Romans applier! veneer to bearing wall construction, usually of massive brick and concrete, we apply it to a skeleton France. The difference between sheathing the Pantheon on one hancI, and the U. N. buiTd- ing on the other, are essentially those inherent in the difference in building frames. We have to clear with n~oven~ent of the material itself as well as rnove~nent in the frame, and taken together these are analog the most critical problems to be solved. Experiments are al- ways being undertaken, and bonding patterns are as changeable in fashion as ladies' hats. The current efforts lean toward thinner and thinner veneers, less emphasis on fully bonded walls except where more permanent or monu- mental structures are involved, and attempts to combine thin stones with metal Frances and panels. Masonry construction has in the past solved exterior wall problems in a superior fashion because of its great strength, (lurability, re- sistance to weather and fire, dimensional stabil- ity, thermal transmission ant] its characteristic graceful weathering. In view of current trends it may well be that beauty in old age will emerge as its most valu- able quality. Strength itself is less important because stone is more likely to be supported than supporting. Fire resistance and thermal transmission may be less of a consideration under current pressures on cocles to revise downward present fire resistant ratings for ex- terior walls. However, weathering and dimen- sional stability will be its prime attraction in any technical development likely to take place. Contemporary design makes heavy clemands for crisp. taut, clean surfaces. With proper selection of stone and correct detailing, ma- sonrv still affords the architect maximum as- surance that a design will retain its original character for the life of the building. 49

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