NRMCA Staff Attends ACI Fall 2023 Convention, Provides Detailed Update

The American Concrete Institute's Fall Convention was held from October 28 to November 2 in Boston. The following is a summary of committee activity involving NRMCA Engineering Staff:

122 – Energy Efficiency of Concrete and Masonry Systems – The committee is working on the review process to finalize ACI 122.2 and 122.3 Thermal Properties of Concrete and Masonry for use in determining Code for residential and nonresidential buildings. The committee discussed whether to let ACI 122R-14 Guide expire; a formal vote will take place at the next committee meeting in mid-November. Darryl Dixon maintains representation in ACI 122.

132 – Responsibilities in Concrete Construction – The committee has reviewed its primary document on responsibilities in concrete construction, compiled substantial comments and is completing the revised version. The committee discussed responsibility of delegated design, primarily for precast concrete, relative to the design criteria needed for the specialty engineer from the engineer of record. The committee sponsored two sessions on responsibility for cracking that were well attended. Colin Lobo maintains representation on ACI 132.

201 – Durability – PRC 201.2R-23 Guide to Durable Concrete has been published with changes to chapters on aggregate reactions, sulfate attack, physical salt attack and abrasion resistance. Other chapters on freezing and thawing, mass transport, chemical attack and corrosion are being revised. Subcommittee 222-0A, comprising of members of Committees 201 and 222, addressed negatives to a balloted draft report on exposure classes related to chlorides.

The committee will publish an article for Concrete International on Effect of Portland Limestone Cement on Concrete Durability. The Guide document will also be updated with this information. NSSGA informed the committee on recent laws passed in Connecticut and Massachusetts regarding testing aggregates for pyrrhotite, a mineral that has resulted in significant deterioration of basement walls. It was suggested that the committee develop guidance based on science to avoid some of the onerous testing requirements for aggregates. Karthik Obla maintains representation in ACI 201.

211 – Mixture Proportioning – The committee is working on the review process to finalize a document on three-point curves for mixture evaluation; resolving ballot negatives on the report on aggregate packing models for optimizing mixtures and is resolving ACI review comments on the Guide to Assessing Combined Aggregate Grading. Karthik Obla maintains representation in ACI 211.

214 – Evaluation of Results of Tests – The committee organized a mini session, Acceptance Testing: How to Do It Right and Why It Matters, that was well attended. There was interest in developing an ACI webinar on the same topic to ensure that acceptance testing is conducted in accordance with standards. Karthik Obla maintains representation in ACI 214.

216 – Fire Resistance and Fire Protection of Structures – The ACI 216 Committee continues to work on the revised version of ACI 216.1, Code Requirements for Determining Fire Resistance of Concrete and Masonry Construction Assemblies, which is nearing completion. The updated edition of the standard will include methodology for performance-based design in addition to prescriptive measures for determining fire resistance. A new chapter on loads in fire addressing strength reduction factors, load factors and load combinations is to be included.

The committee is also finalizing the new rational design guide on determining fire resistance. The committee discussed developing a Tech Note regarding the equivalence of Portland Limestone Cement to ordinary cement in terms of fire resistance. A mini session on fire safety within the International Building Code was co- presented by NRMCA's Shamim Rashid-Sumar and ICC’s Samhar Hoz, with an emphasis on vertical and lateral flame propagation in exterior walls. Shamim Rashid-Sumar maintains representation on ACI 216.

232 – Fly Ash – The committee organized a mini session titled Strategies to Use Available Supplementary Cementitious Materials that summarized the work from the recently concluded NCHRP project on marginal fly ash as well as other funded projects on alternative SCMs. Karthik Obla maintains representation on ACI 232.

240 – Natural Pozzolans – The committee is working on two tech notes, What is a Pozzolan and a report on Ground Glass Pozzolan. The committee considered some proposals of projects that are looking for endorsement for funding from the ACI Foundation. The proposal from the University of Miami that is investigating the ASTM standardization of the Bulk Resistivity test for distinguishing Supplementary Cementitious Materials from inert fillers was strongly supported. Karthik Obla maintains representation on ACI 240.

301 – Specifications for Structural Concrete – The committee continues its process of resolving comments to proposed changes to several sections of the specification: submittal requirements for sustainability, requirements for alkali aggregate reactions, architectural and tilt-up concrete, post tenstioned systems, mass concrete, industrial floor slabs and shrinkage compensating concrete. The committee will address approved revisions to ACI 318 to be incorporated in ACI 301 specification.

The committee received presentations regarding tracking carbon emissions during construction: Consigli summarized the contractors' commitment to track this information while Turner Construction presented on quantifying and reducing jobsite carbon emissions related to equipment used. The committee discussed harmonizing terminology used for joints in ACI 301 and other ACI documents. Colin Lobo maintains representation on ACI 301.

318 – Building Code for Structural Concrete – This was the last opportunity to approve changes to the next version of ACI 318 that will be published in Spring 2025. Related to concrete mixtures, the committee approved a change to the durability provisions to remove exposure class F3 for exposure to freezing and thawing. This eliminates maximum limits on SCMs in ACI 318. Several other change proposals to the chapters on materials (Ch 19) and construction documents (Ch 26) were previously approved.

A new appendix on sustainability developed by Subcommittee N was approved during this meeting, overriding some negatives that did not want to include this in this Code. The Appendix on sustainability is optional and covers design of structural system for sustainability, system resilience and documenting reduced environmental impact of concrete mixtures. ACI 318 defines the process but permits the designer to set appropriate limits for projects for reduced environmental impact.

ACI 318 will be subject to review by ACI Technical Activity Committee followed by a period for public comment before it is finalized. Colin Lobo maintains representation on Subcommittees A and N and on the 318 main Committee.

323 – Low Carbon Concrete Code – The mission of the ACI 323 Committee is to develop and maintain code requirements for low-carbon concrete. The scope of ACI 323 is limited to cast-in-place concrete structures and its purpose is to provide requirements for the maximum global warming potential of concrete. This new code is intended for publication in 2025. The committee focused on finalizing revisions to the draft code based on previous committee comments. The draft will be sent to TAC for review and subsequently opened for public comment. Tiffany Reed-Villarreal will maintain representation on ACI 323.

325 – Concrete Pavements – The committee currently has four documents under development or revision. The committee is rewriting ACI 325.12R-02 (Reapproved 2019): Guide for Design of Jointed Concrete Pavements for Streets and Local Roads led by NRMCA's Brian Killingsworth. Revisions to this document have been completed and TAC has returned comments to which the committee is responding. The updated guide should be published in 2024.

The committee is developing ACI 325.YR Report on Precast Concrete Pavements - State of the Practice which is based upon work completed by Tayabji for the FHWA. Work is also underway to update ACI 325.ZR: Design and Construction of Continuously Reinforced Concrete Pavements. This work will continue over the next year. ACI 325.13R-06: Concrete Overlays for Pavement Rehabilitation has also been updated and has been balloted. The committee is working through negatives from the balloting process and will be forwarded to TAC in early 2024. Brian Killingsworth maintains representation on ACI 325 on concrete pavements.

327 – Roller-Compacted Concrete Pavements – The committee continues to work on ACI SPEC-327.Y – Construction of Roller-Compacted Concrete Pavements – Specification. The draft specification document has been reviewed by the ACI specification committee and returned for additional work and corrections. After revising, balloting is anticipated to be in late winter 2023 or early spring 2024. The committee is also rewriting ACI PRC-327-14 – Guide to Roller-Compacted Concrete Pavements led by NRMCA's Greg Halsted. The Guide document is currently being balloted in four sections with the updated Guide anticipated to be published by summer or fall 2024. A mini session titled Innovations and Latest Trends in RCC Pavements was presented before the recent committee meeting and attracted approximately 45 participants. Halsted will ensure that considerations for sustainable streets and local roads will be included in all documents. Greg Halsted maintains representation on ACI 327 as chairman/

329 – Performance Criteria for Ready Mixed Concrete – ACI 329 is working on developing a guide to writing a performance specification. Some progress was made toward describing tests that could be used to evaluate performance properties of concrete mixtures. The committee will ballot recommended specification language and commentary for the recommended performance specification. MasterSpec section 033000 format is being used for this document. Karthik Obla and Colin Lobo maintain representation on ACI 329.

330 – Parking Lots – The committee is completing the ACI review process to finalize the ACI 330.1 specification. The final response to TAC comments were voted on during the meeting. A presentation on expansion joints was given by Jim Mack. The Expansion Joint Task Group presented language to be added to the document. The committee agreed more time was needed to address expansion joints. Amanda Hult maintains representation in ACI 330.

332 – Residential Concrete – Educational presentations were delivered to the committee on level of industry data to adopt provisions governing 3D printed concrete, basement wall design optimization and updates on Portland Limestone Cement. The ACI 332 Committee’s work on updating ACI 332-20: Code Requirements for Residential Concrete and Commentary to include a new chapter on Above Grade Walls is progressing steadily.

The committee is incorporating provisions from NRMCA 100, Prescriptive Design of Exterior Concrete Walls for One- and Two-Family Dwellings, into the revised Code, with the goal of referencing the revised edition of ACI 332 into the 2027 edition of the International Residential Code (IRC). Subcommittee B is considering potential work on a performance-based code for the freeze thaw durability on non-structural elements. Subcommittee D is considering a Tech Note for the creation of retaining walls of four feet or less in height. The committee is also working to incorporate provisions and minimum requirements for 3D-printed concrete residential structures into the 332 Code. Julian Mills-Beale maintains membership on ACI 332.

522 – Pervious Concrete – The committee hosted a mini sessions that included topics on precast pervious panels, moss control, certification and testings, and regulatory environment governing use of pervious concrete. The committee discussed revisions to its guide document on pervious concrete with suggested editorial revisions to improve the flow of the document. Potential research topics were offered but nothing specific was identified. Amanda Hult maintains representation in ACI 522.

551 – Tilt-Up Concrete Construction – The committee continues to review and update its two publications, ACI 551.1R Guide to Tilt-Up Concrete Construction and ACI 551.2R Design Guide for Tilt-Up Concrete Panels. Many items were identified as needing improvement and updates and many others were submitted having been updated and improved. Design examples were discussed in detail and it was suggested to hand them over to ACI or create an RFP for proposals from a third-party source. Darryl Dixon maintains representation in ACI 551.

560 – ICF Buildings – The committee has commenced review and update of its report publication, ACI PRC-560-22: Insulating Concrete Form Design and Construction. The committee is reviewing provisions for control joints, minimum horizontal reinforcement, and placement and consolidation of concrete in ICF walls. Other considerations for the update include fiber reinforcement, macro synthetic fibers and non-metallic reinforcement. An update was provided on the status of NRMCA 100, Prescriptive Design of Exterior Concrete Walls for One- and Two-Family Dwellings, which is nearing publication as an ANSI standard. An update was also provided on the status of NRMCA and ICFMA’s joint project on NFPA 285 testing for insulated concrete form exterior wall assemblies. Julian Mills-Beale and Shamim Rashid-Sumar maintain representation on ACI 560.

Concrete Research Council (CRC) – The Research Council of the ACI Foundation annually funds research programs and is soliciting projects in categories of materials, design and construction. Proposals are due by December 1. CRC can fund about eight research projects, with each receiving funding of $50,000. The committee is finalizing its selection of award recipients for the Philleo Award on concrete materials research and the Boase Award for research on structural systems. Colin Lobo maintains representation on ACI CRC.

Other – Shamim Rashid-Sumar co-presented with ICFMA’s Robert Sculthorpe on Fire Testing of ICF Wall Construction at NEx’ third workshop focusing on FRP Composites in the Face of Fire: Insights from Research and Industry. (See related news item under the Buildings section.)

At the ACI Committee 302 (Construction of Concrete Floors) meeting, a summary of a survey on the use of concrete made with portland limestone cement (PLC) on constructability of floor slabs was presented. Committee 134 on constructability hosted a mini-session on contractor experiences on constructability with concrete made with PLC. Problems with finishing, early age strength and setting time, bleed characteristics were discussed. There were other sessions with topics covering testing for modulus of elasticity, issues with acceptance testing of concrete, and some possible changes to requirements related to alkali aggregate reactions.

For more information, click here to access contact information for NRMCA personnel mentioned in this report.