NRMCA Engineering Staff Files Detailed Summary from ACI Fall 2023 Convention

The American Concrete Institute's Fall Convention was held from Octiober 23 - 27, 2023, in New Orleans. NRMCA Engineering Staff summarized key committee activity below:

122 – Energy Efficiency of Concrete and Masonry Systems – The committee has finalized ACI 122.2 and 122.3 Thermal Properties of Concrete and Masonry for use in determining Code for residential and nonresidential buildings. However, there has been a delay by ACI in publishing and releasing the documents to the public which has delayed committee discussions on whether to let ACI 122R-14 Guide expire. A formal vote will take place at the next committee meeting in early November. ACI has given preliminary approval to 122 for a full session at the next convention in Philadelphia; there are five speakers slated to speak during the 2-hour session. 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 sponsored two sessions on responsibility when sustainable concrete does not meet performance expectations. The sessions discussed the various codes and sustainability initiatives; realistic expectations of demands for low-carbon concrete; designer’s challenges for establishing project goals consistent with Code requirements; potential variability of low carbon materials; challenges for constructability; impact of testing on achieving low carbon concrete; clashes of performance with low-carbon expectations and legal aspects. Colin Lobo maintains representation on ACI 132.

201 – Durability – PRC 201.2R-23 Guide to Durable Concrete - changes to the chapter on freezing and thawing were discussed. Other chapters on 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. This document will be balloted by the ACI 222 committee. Karthik Obla maintains representation in ACI 201.

211 – Mixture Proportioning – The committee resolved a ballot responding to TAC comments to the new PRC-211.X: Assessing Combined Aggregate Gradings guide. The committee is responding to TAC comments on a Tech Note on three-point curves for mixture evaluation and is resolving a ballot on a report on aggregate packing models for optimizing mixtures. The committee balloted several changes to the Guide to Troubleshooting Concrete Mixture Issues as Influenced by Constitutive Materials, Jobsite Conditions. The committee also discussed adding a water demand section for Type IL cements and doing a member survey to determine appropriate coarse aggregate proportions (b/bo table) in the ACI PRC-22.1-22 document. Karthik Obla maintains representation in ACI 211.

214 - Evaluation of Results of Tests – The committee assigned individuals to work on different chapters of ACI PRC-214-11 Guide to Evaluation of Strength Test Results of Concrete. The committee assigned individuals to review NRMCA TIP 23 on Establishing Required Averages for Specified Properties for possible development into an ACI document. Karthik Obla will serve as the committee chair.

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. A task group of the committee, led by Shamim Rashid-Sumar, is developing a Tech Note regarding the equivalence of Portland Limestone Cement to ordinary cement in terms of fire resistance. Shamim Rashid-Sumar maintains representation on ACI 216.

232 – Fly Ash – The committee discussed the report on use of bottom ash in concrete. There were discussions on needing to include the Fluidized Bed Combustion ash in ASTM C618. Karthik Obla maintains representation on ACI 232.

240 – Natural Pozzolans – The committee is working on a tech note titled What is a Pozzolan and a report on Ground Glass Pozzolan. The committee discussed changes to the natural pozzolan document ACI 232.1-12 and is transferring this to be addressed by this committee. The committee discussed new Tech Notes on Calcined Clay; Manufactured Pozzolans and a new report on How to Evaluate new SCMs. The committee had presentations on new cements – Brimstone, Sublime cement and Terra CO2. Karthik Obla maintains representation on ACI 240.

301 – Specifications for Structural Concrete – The committee continues to resolve comments to finalize proposed changes to several sections of the specification – submittal requirements for sustainability, requirements for alkali aggregate reactions, post tenstioned systems and industrial floor slabs. The committee will update ACI 301 to incorporate approved revisions to ACI 318 that impact the specification; include provisions for use of fibers for various applications; and address sampling and testing at points of delivery or placement. Colin Lobo maintains representation on ACI 301.

318 – Building Code for Structural Concrete – The committee is in the final phases of completing Code changes for this cycle. This meeting was dedicated to resolving responses to comments from ACI Technical Activities Committee (TAC). There were no changes to Chapter 19 and 26 that cover concrete materials. The revised Code will include new content in Appendices for performance-based wind design and sustainability. The committee addressed development length provisions in 318-19 that were resulting in constructability problems. Separate codes for precast structural concrete (ACI 319) and post-tensioned structural concrete (ACI 320) will be published with cross-reference to provisions in ACI 318.

ACI 318 will be available for public comment in summer. The committee will complete responses to public comments and any associated revisions to finalize ACI 318 at the ACI convention in November and publish ACI 318-25 early in 2025. This will permit ACI 318-25 to be referenced by the International Building Code.
Colin Lobo maintains representation on Subcommittees A (concrete materials) and N (sustainability) 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. The draft standard is being processed through ACI’s consensus-based standardization procedure and is currently open for public discussion from March 31 through May 15. Tiffany Reed-Villarreal maintains 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 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 and will be re-balloted. ACI 325.13R-06: Concrete Overlays for Pavement Rehabilitation has also been updated, balloted and submitted to staff for TAC review. 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 subcommittee working on the specification document has received some new help which should aid in having something to send to the ACI specification committee later in 2024. The main committee is also rewriting ACI PRC-327-14 – Guide to Roller-Compacted Concrete Pavements led by Greg Halsted. The guide document is currently being balloted in four sections, with three of the sections passing overwhelmingly and the fourth section out to ballot now. The goal is to have all four sections (with all comments resolved) to TAC before the end of April with completion hopefully before the end of 2024.

A mini session titled Revolutionizing RCC Pavements: Design Parameters, Construction Techniques, and Sustainable Advantages was organized during the committee meeting and scheduled for presentation during the ACI Fall 2024 Concrete Convention in Philadelphia. Halsted will ensure that considerations for sustainable streets and local roads will be included in all documents. He maintains representation on ACI 327 as chair.

329 – Performance Criteria for Ready Mixed Concrete – ACI 329 is working on developing a guide to writing a performance specification. Using the most recent version of MasterSpec section 033000, the committee balloted recommended specification language and commentary for Section 1 of the guide performance specification. The committee has completed a significant chapter briefly discussing several performance-based test methods and specification criteria using these methods. Section 2 (Products) of the specification that will outline and discuss permitted materials and performance-based requirements for various structural members is being developed. Karthik Obla and Colin Lobo maintain representation on ACI 329.

330 – Parking Lots – The ACI 330.1 specification is available for public comment and will close on April 4. The committee will address public comments through web meetings. At this time, the committee has agreed to adopt the tolerances from ACI 117. Changes made to ACI 117 on tolerances will be reviewed and considered in the 330 documents as necessary. A Task Group is developing guidance on the potential for concrete expansion in parking lots. Recommendations will be presented in Philadelphia. Amanda Hult maintains representation in ACI 330.

332 – Residential Concrete – 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 ongoing. A proposed Tech Note for short retaining walls four feet or less on foundations, by Subcommittee D, is in the pre-developmental stages. Subcommittee E has started to incorporate the newly approved NRMCA 100, Prescriptive Design of Exterior Concrete Walls for One and Two-Family Dwellings into the revised code. Upon completion, the committee will immediately pursue referencing the revised edition of ACI 332 into the 2027 edition of the International Residential Code (IRC).

To fill in knowledge gaps, the Subcommittee F on slabs is currently considering critical topics for its upcoming Technical Note publication. The 332-G Subcommitee is earmarking a number of mini sessions and technical presentations to raise awareness about the Guide to Residential Concrete Construction at future ACI events. Julian Mills-Beale maintains membership on ACI 332.

522 – Pervious Concrete – The committee discussed revisions to its guide document on pervious concrete with suggested editorial revisions to improve the flow of the document. ACI is also considering management of the pervious concrete contractor certification currently managed by NRMCA. The 522 committee expressed willingness to assist ACI with content review and updating material. Dr. John Kevern will be the new chair of the committee. Amanda Hult maintains representation in ACI 522.

551 – Tilt-Up Concrete Construction – The committee addressed negatives from balloting on both ACI 551.1R Guide to Tilt-Up Concrete Construction and ACI 551.2R Design Guide for Tilt-Up Concrete Panels. Many items were discussed and voted upon while others required additional review and reflection. Design examples were discussed briefly before time ended and it was again 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’s review and update of ACI PRC-560-22 Insulating Concrete Form Design and Construction is in progress. A virtual meeting planned for September 6 will discuss potential ballot items ahead of the fall convention in Philadelphia. NRMCA 100, Prescriptive Design of Exterior Concrete Walls for One- and Two-Family Dwellings is now an ANSI-approved standard and the publication is readily available to the public via the NRMCA bookstore. The NRMCA and ICFMA joint project on NFPA 285 testing for insulated concrete form exterior wall assemblies has made significant progress and is targeted for completion by end of the 2024. Julian Mills-Beale and Shamim Rashid-Sumar maintain representation on ACI 560.

Concrete Research Council (CRC) – The Research Council of the ACI Foundation funds research programs annually. The council reviewed about 25 research proposals and selected eight research projects for funding for 2024. Each project is funded at $50,000. Projects require support from ACI committees so that the research can support their initiatives and documents. Most projects have supplemental funding from other sources. Projects are considered under the general themes of materials, structural design and construction. Projects accepted for funding will be notified in about one month. Reports of previous and ongoing projects are available on the website of the ACI Foundation. Colin Lobo maintains representation on ACI CRC.

Other – ACI organized four sessions and a reception honoring the legacy of Professor Ken C. Hover who recently retired from Cornell University. Dr. Hover is recognized for his considerable contribution to the concrete industry; being an excellent presenter on a wide range of topics on concrete technology and as a past president of ACI. Dr. Hover is also a recipient of the NRMCA Richard D. Gaynor Award.

For more information, contact the relevant staff member(s) listed above by using the NRMCA directory.