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T-1 A P P E N D I X T AAshto Construction specification
T-2 SECTION 29 EMBEDMENT ANCHORS 29.1-DESCRIPTION This work shall cover installation and field testing of cast-in-place, grouted, adhesive-bonded, expansion, and undercut steel anchors. C29.1 The use of embedment anchors is prevalent but standardized installation and field testing is not. Therefore, a new section was created. 29.2-PREQUALIFICATION Concrete anchors, including cast-in-place; all bonded anchor systems, including grout, chemical compound and adhesives; and undercut steel anchors shall be prequalified by universal test standards designed to allow approved anchor systems to be employed for any construction attachment use. Only adhesive anchor systems that meet the assessment criteria of ACI 355.4 âQualification of Post-Installed Adhesive Anchors in Concreteâ are approved for use with the AASHTO design provisions. Adhesive anchors to be installed under special conditions that require optional tests in ACI 355.4 (i.e., water-filled holes, submerged concrete, installation temperature less than 50°F, and in horizontal or upwardly inclined holes), must be specifically approved by ACI 355.4 for these conditions. Expansion anchors shall be tested in accordance with ASTM E488, Standard Test Methods for Strength of Anchors in Concrete and Masonry Elements. Embedment anchor details shall comply with ACI 349, Code Requirements for Nuclear Safety Related Concrete Structures, "Appendix B, Steel Embedments." For anchor systems other than mechanical expansion anchors, the Contractor shall provide the Engineer with certified test reports prepared by an independent laboratory documenting that the system is capable of achieving the minimum tensile strength of the embedment steel. C29.2 ACI 355.4 provides the testing and acceptance criteria for adhesive anchors in concrete. ACI 355.4 was originally developed by ICC-ES as AC-308. ACI 355.4 utilizes test methods established in ASTM E488 and ASTM E1512. 29.3-MATERIALS Mill test reports shall be provided to the Engineer to certify physical properties, chemistry, and strengths used to manufacture the anchors. Adhesive anchor systems are qualified for different anchor element types and coatings and only those anchor types and coatings specifically mentioned in the Manufacturerâs Printed Installation Instructions (MPII) shall be used. Either an epoxy, vinylester, or polyester chemical compound shall be acceptable for adhesive anchors. Adhesive anchor systems acceptable for use include, but are not limited to, epoxies, polyurethanes, polyesters, methyl methacrylates, and vinyl esters. Moisture-insensitive, high- modulus, low shrinkage, and high-strength adhesives shall be used. Only adhesive anchor products that meet the assessment criteria of ACI 355.4 shall be used. Adhesive C29.3 Due to the sensitivity of bond strength to installation, on-site quality control is important for adhesive anchors. Where appropriate, a proof loading program should be specified in the contract documents. For adhesive anchors, the contract documents must also provide all parameters relevant to the characteristic bond stress used in the design. These parameters may include, but are not limited to: 1. Acceptable anchor installation environment (dry or saturated concrete; concrete temperature range); 2. Acceptable drilling methods; 3. Required hole cleaning procedures; and 4. Anchor type and size range (threaded rod or reinforcing bar). Hole cleaning is intended to ensure that drilling debris and dust do not impair bond. Depending on the on-site conditions, hole cleaning may involve operations to remove
T-3 anchor systems may include not only the adhesive material but the anchor, all the equipment provided by the manufacturer for proper installation and cleaning of the hole, and the MPII. Bulk adhesives mixed in open containers without automatically controlled metering and mixing of components are not permitted. Materials should be stored in unopened containers and according to the storage conditions specified in the MPII. Materials should be discarded once the expiration date has expired. For adhesive anchors, the contract documents shall specify proof loading where required. The contract documents shall also specify all parameters associated with the characteristic bond stress used for the design including minimum age of concrete; concrete temperature range; moisture condition of concrete at time of installation; type of lightweight concrete, if applicable; and requirements for hole drilling and preparation. The use of additives to grout and bonding materials that are corrosive to steel or zinc/cadmium coatings shall be prohibited. drilling debris from the hole with vacuum or compressed air, mechanical brushing of the hole wall to remove surface dust, and a final step to evacuate any remaining dust or debris, usually with compressed air. Where wet core drilling is used, holes may be flushed with water and then dried with compressed air. If anchors are installed in locations where the concrete is saturated (for example, outdoor locations exposed to rainfall), the resulting drilling mud must be removed by other means. In all cases, the procedures used should be clearly described by the manufacturer in printed installation instructions (MPII) accompanying the product. These printed installation instructions, which also describe the limits on concrete temperature and the presence of water during installation as well as the procedures necessary for void-free adhesive injection and adhesive cure requirements, constitute an integral part of the adhesive anchor system and are part of the assessment program. 29.4-CONSTRUCTION METHODS Adequate edge distance, embedment depth, and spacing to develop the required strength of the embedment anchors and to ensure ductility of the connection shall be provided. The correct drill-hole diameter shall be used as specified by the Manufacturerin the MPII. Rotary impact drilling with carbide-tipped hammer bits conforming to ANSI B212.15 shall be used unless diamond core drilling is permitted by the MPII and has been specified approved by the Engineeror tested. If a reinforcing bar is encountered during drilling, the hole shall be moved to a different location or the reinforcing steel shall be drilled through using a diamond core bit as directed by the Engineer. Once the reinforcing steel is cut, the drilling should resume with a rotary impact drill. Abandoned holes shall be patched with an approved bonding material. Holes shall be thoroughly cleaned as recommended by the Manufacturerspecified in the MPII. Adhesive anchors shall only be installed in concrete that is at least 21 days old and has a minimum compressive strength of 2500 psi at the time of installation. Adhesive anchors that are installed in the horizontal or upwardly inclined direction shall be installed by personnel certified by the ACI/CRSI Adhesive Anchor Installer Certification program, or its equivalent. The Contractor shall remove all loose dust and concrete particles from the hole and protect the hole from contamination until the anchor is installed. The Contractor shall prepare bonding material and install anchors according to the Manufacturer's instructions MPII.or as approved by the Engineer. Unless otherwise indicated, anchors shall be installed perpendicular to the concrete surface. Adhesive anchors that displace prior to full adhesive cure shall be replaced at the Contractorâs expense. Adhesive Anchors cannot be adjusted by bending with a pipe or by hammering unless approved by the Engineer. Improperly installed embedded anchors or anchors not C29.4 The MPII provided with the adhesive anchor system includes the instructions for the correct installation procedure. The approval and acceptance of adhesive anchor systems is based on strict adherence to the MPII. This includes but is not limited to drilling procedures (drill type, drill bit type and diameter), hole cleaning procedures (blowing, vacuuming, brushing), installation conditions (dry, moist, or submerged hole, adhesive temperature, and concrete temperature), adhesive dispensing procedure (discarding initial adhesive, maintaining nozzle tip submerged during dispensing), and adherence to gel/working and curing times. While adhesive anchors are not particularly sensitive to concrete compressive strength, ACI 318 adopts the 21 day limit on adhesive anchor installation due to adhesive anchor sensitivity to various early-age concrete properties such as moisture content and tensile strength. The installation of adhesive anchors in horizontal or upwardly inclined holes presents unique difficulties and careful installation and monitoring is required. Therefore ACI 318 requires personnel certified by the ACI/CRSI Adhesive Anchor Installer Certification program or its equivalent for these installations. It is suggested that a drilling rig similar to that shown below be used to help ensure that the hole is drilled perpendicular to the surface. It is also suggested that an adaptor similar to that shown below be used to protect the operator while blowing with compressed air and vacuuming the loose dust and concrete particles from the hole.
T-4 having the required strength shall be remo to the satisfaction of the Engineer at expense. 29.5-INSPECTION AND TESTING Adhesive anchors installed in horizon inclined holes shall be continuously inspect inspector. Adhesive anchors subjected to in-serv of 120°F shall be qualified under temperatu ACI 2355.4 §8.5 at a temperature equal to o highest in-service temperature. Each type and size of adhesive ancho tested in accordance with ACI 355.4. P adhesive anchors shall be conducted only a curing time as specified in the MPII has elap Where specified, sacrificial tests of th shall be done at the job site to ultimate loads capability of the system to achieve pullout l full minimum tensile value of the anchor em testing shall be done on fully cured conc least three anchors shall be tested by ASTM unless otherwise specified. The Contract prequalified anchor systems meeting the abo Provision shall be made for use of an a that will reach the designated pullout requ delay in progress, if the job site proof incapable of achieving minimum tensile va required by the Engineer if too little concret to develop full ductile loads. After installation and cure of the bondi anchor system shall be torqued to specifie MPII as a result of ACI 355.4 qualificat approved torque methods only. If torque specified, the Manufacturer's recommend provided by the Engineer shall be used. For used in sustained load applications, the an permitted to be loaded or torqued manufacturerâs minimum cure time as listed an additional 24 hours. 29.6-MEASUREMENT Measurement of embedment anchors the project shall be the number of each orientation shown in the contract documen for use on the project. Each embedme satisfactorily installed shall be counted an ved and replaced the Contractor's tal or upwardly ed by a qualified ice temperatures re category B of r greater than the r shall be proof roof loading for fter the minimum sed. e anchor system to document the oads equaling the ployed. Anchor rete samples. At E488 methods, or may use any ve requirements. lternative system irement, without loading proves lues, or the load e exists in which ng material, each d values per the ion testing using values are not ation or values adhesive anchors chor shall not be until after the in the MPII plus incorporated into anchor size and ts or authorized nt anchor type d summarized in
T-5 the contract documents according to anchor system; orientation, i.e., vertical, horizontal, and diagonal; and size taken as the diameter. 29.7-PAYMENT Payment shall be based upon the quantity of embedment anchors determined under measurement for each embedment anchor type and shall include full compensation for furnishing all labor, materials, tools, equipment, testing, and incidentals necessary to place each anchor type. 29.8-REFERENCES ACI. 2001. Code Requirements for Nuclear Safety Related Concrete Structures, ACI 349-01, American Concrete Institute, Farmington Hills, MI, Appendix B: Steel Embedments. ACI 2011. Building Code Requirements for Structural Concrete, ACI 318-11, American Concrete Institute, Farmington Hills, MI. ACI 2011. Qualification of Post-Installed Adhesive Anchors in Concrete, ACI 355.4-11, American Concrete Institute, Farmington Hills, MI.
Abbreviations and acronyms used without deï¬nitions in TRB publications: A4A Airlines for America AAAE American Association of Airport Executives AASHO American Association of State Highway Officials AASHTO American Association of State Highway and Transportation Officials ACIâNA Airports Council InternationalâNorth America ACRP Airport Cooperative Research Program ADA Americans with Disabilities Act APTA American Public Transportation Association ASCE American Society of Civil Engineers ASME American Society of Mechanical Engineers ASTM American Society for Testing and Materials ATA American Trucking Associations CTAA Community Transportation Association of America CTBSSP Commercial Truck and Bus Safety Synthesis Program DHS Department of Homeland Security DOE Department of Energy EPA Environmental Protection Agency FAA Federal Aviation Administration FHWA Federal Highway Administration FMCSA Federal Motor Carrier Safety Administration FRA Federal Railroad Administration FTA Federal Transit Administration HMCRP Hazardous Materials Cooperative Research Program IEEE Institute of Electrical and Electronics Engineers ISTEA Intermodal Surface Transportation Efficiency Act of 1991 ITE Institute of Transportation Engineers MAP-21 Moving Ahead for Progress in the 21st Century Act (2012) NASA National Aeronautics and Space Administration NASAO National Association of State Aviation Officials NCFRP National Cooperative Freight Research Program NCHRP National Cooperative Highway Research Program NHTSA National Highway Traffic Safety Administration NTSB National Transportation Safety Board PHMSA Pipeline and Hazardous Materials Safety Administration RITA Research and Innovative Technology Administration SAE Society of Automotive Engineers SAFETEA-LU Safe, Accountable, Flexible, Efficient Transportation Equity Act: A Legacy for Users (2005) TCRP Transit Cooperative Research Program TEA-21 Transportation Equity Act for the 21st Century (1998) TRB Transportation Research Board TSA Transportation Security Administration U.S.DOT United States Department of Transportation
