The American Concrete Institute's Spring 2023 Convention was held between April 1 - 6 in San Francisco. What follows is a summary of relevant committee activity involving NRMCA staff.
132 – Responsibilities in Concrete Construction – The committee published ACI PRC-132.2-22: Responsibility in Concrete Rehabilitation Construction – Guide that is available from ACI. The committee planned speakers and responsibility focus areas on cracking. Speakers representing different stakeholder groups have been selected for a two-session event at an upcoming convention. The committee has reviewed its primary document on responsibilities in concrete construction, compiled substantial comments and working in its revised version. Colin Lobo maintains representation on ACI 132.
201 – Durability – Several chapters of the guide to durable concrete (201.2R) are being updated, including the one on freeze-thaw as well as a new chapter on Chemical Attack. Subcommittee 222-0A comprising of members of Committees 201 and 222 is working on a report on exposure classes related to chlorides and applicable requirements for concrete. 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. A subcommittee is completing a report on aggregate packing models for optimizing mixtures. Karthik Obla maintains representation in ACI 211. The committee is also completing a Guide to Assessing Combined Aggregate Gradings.
214 – Evaluation of Results of Tests – The committee decided to work on updating the Guide Document PRC 214.4 to include guidance on dealing with outlier core test results. There is interest in developing some sessions and webinars for local state chapters on ensuring third-party testing is performed in accordance with standards. The committee is trying to develop supporting documentation on the table listing the standards of concrete control. Karthik Obla maintains representation in ACI 214.
216 – Fire Resistance and Fire Protection of Structures – The ACI 216 Committee continues to work on revisions to ACI 216.1, Code Requirements for Determining Fire Resistance of Concrete and Masonry Construction Assemblies. The updated edition of the standard includes a new chapter on loads in fire addressing strength reduction factors, load factors and load combinations. Additionally, the committee is finalizing the new rational design guide on determining fire resistance. The document provides guidelines for determining fire resistance through analytical methods in addition to the existing prescriptive methods. Shamim Rashid-Sumar maintains representation on ACI 216.
232 – Fly Ash – In collaboration with many industry associations, the American Coal Ash Association is developing a Product Category Role (PCR) for fly ash and natural pozzolans to allow its marketers to prepare Environmental Product Declarations (EPDs). The task is estimated to be completed in two months. The PCR will apply to all supplementary cementitious materials (SCMs). The committee is working on a new report on the use of crushed bottom ash as a supplementary cementitious material. The report on high-volume fly ash concrete will be updated with new research to provide guidance on its use in high early-strength applications. There was an update on the various research projects addressing fly ash supply, which should be completed by June 2023. Karthik Obla maintains representation on ACI 232.
240 – Natural Pozzolans – The committee voted to take over the document PRC-232 Report on the Use of Raw or Processed Natural Pozzolans in Concrete from ACI 232 and start making revisions. This activity was also supported by Committee 232. The committee is working on two tech notes, What is a Pozzolan and a report on Ground Glass Pozzolan. Karthik Obla maintains representation on ACI 240.
301 – Specifications for Structural Concrete – The subcommittee responsible for Section 4 on concrete mixtures ballotted a significant reorganization of the section on concrete materials to consolidate and categorize submittals and other revisions related to alkali-silica reactions and approved changes to ACI 318. The committee worked on resolving comments through a ballot. Subcommittee responsible for post-tensioned systems in Section 9 is working on developing separate sections for bonded and unbonded PT construction. A ballot was issued to include submittals for sustainability in 301 (Section 1) and this will need a considerable resolution. Colin Lobo maintains representation on ACI 301.
318 – Building Code for Structural Concrete – ACI Subcommittee A on Concrete Materials is completing its work on several code change proposals. Approved items by the main committee at this meeting include provisions for curing that are based on time or could be shortened based on estimated in-place strength; provisions for hot and cold weather concrete; clarifying acceptance of lightweight concrete for specified equilibrium density; and minimizing content in portions of the commentary in Chapter 26. Outstanding items include removing Exposure Class F3 and the limits on SCMs for concrete exposed to deicer scaling, and addressing sampling at the point of placement at the option of the designer.
Subcommittee N on sustainability had essentially resolved all its negatives on the content of the proposed appendix. However, one voter objected to including this content in the structural building code for several reasons. The vote to do this prevailed by a small margin. 318 Committee leadership will decide on a resolution. The appendix is not mandatory but can be used by the designer if there is a sustainability goal on a project. The appendix includes structural system sustainability, system resilience and documenting concrete materials for reduced environmental impact.
ACI 318 is working toward publishing the revised code in 2025. Most of the new content to the code has to be approved by Fall 2023. Colin Lobo maintains representation on Subcommittees A and N and on the 318 main committee.
323 – Low-Carbon Concrete Code – The ACI Technical Activities Committee has established a new committee, ACI 323, on Low-Carbon Concrete. The mission is to develop and maintain code requirements for low-carbon concrete and the scope is limited to the reduction of embodied carbon in concrete. A kickoff meeting for the committee was held at the Spring Convention. The new code is intended to have a quick turnaround for publication within the 2025 code cycle. While the committee is currently focused on the immediate need for consistent code language for low-carbon concrete, the longterm vision of the committee is to address sustainability and resilience. Shamim Rashid-Sumar currently maintains representation on ACI 323.
325 – Concrete Pavements – A mini session on sustainability was moderated by Brian Killingsworth with very good attendance. The committee currently has four documents under development or revision. The committee is rewriting ACI 325.12R-02 (Reapproved 2014): Guide for Design of Jointed Concrete Pavements for Streets and Local Roads led by 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 is currently being balloted. Killingsworth will ensure that considerations for streets and local roads will be included in all documents. He maintains representation on ACI 325 on concrete pavements.
327 – Roller-Compacted Concrete Pavements – The committee is completing work on ACI SPEC-327.Y – Construction of Roller-Compacted Concrete Pavements – Specification. The specification document is being sent to the ACI specification committee for review before the balloting process. Balloting is anticipated to be in late summer or early fall 2023. The committee is also rewriting ACI PRC-327-14 – Guide to Roller-Compacted Concrete Pavements led by Greg Halsted. The guide document will be balloted in four sections starting in late spring 2023 with the updated guide published in late 2023 or early 2024. A mini session titled Innovations and Latest Trends in RCC Pavements has been submitted and approved for presentation at the ACI Fall 2023 Convention. The committee also discussed the development of a TechNote on RCC Composite Pavements with a request being submitted to TAC for permission to produce the document. Halsted will ensure that considerations for sustainable streets and local roads will be included in all documents. He 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. The committee discussed performance tests and criteria for various exposure classes that will be part of Section 2 (Products) and an intent to revise and reballot Section 1 (General) of the spec. The committee also identified the remaining items to be balloted in a chapter that briefly describes various test methods for concrete. Committee ACI 134 is putting together a session Prescriptive or Performance? What is the state of the industry and what are examples of a positive movement toward collaboration? Karthik Obla and Colin Lobo maintain representation on ACI 329.
330 – Parking Lots – The ACI 330 Committee is completing the ACI review process to finalize the ACI 330.1 specification. TAC comments were reviewed and changes were voted on during the meeting. A mini-session on expansion joints was presented. An Expansion Joint Task Group was formed to evaluate and address language for the upcoming document revision. Amanda Hult maintains representation in ACI 330.
332 – Residential Concrete – The ACI 332 Committee is moving forward with its plans to update ACI 332-20: Code Requirements for Residential Concrete and Commentary to include a new chapter on Above Grade Walls. The committee intends to incorporate references and provisions of NRMCA 100, Prescriptive Design of Exterior Concrete Walls for One- and Two-Family Dwellings, into the revised code. The committee is working toward reference of the revised edition of ACI 332 into the 2027 edition of the International Residential Code (IRC). Julian Mills-Beale maintains membership on ACI 332.
522 – Pervious Concrete – The ACI 522 Committee completed the ACI PRC 522, Guide to Pervious Concrete revision with an anticipated early 2023 release. Research funding was discussed along with potential new research activities. A mini session on materials, proper maintenance and innovation for pervious was held. Killingsworth spoke to the committee about transferring the pervious concrete contractor personnel certification to ACI. Discussions will continue until an agreement is in place. The pervious competition was held at the Fall 2022 meeting and the Education Subcommittee will be reviewing and evaluating changes for the next competition. Amanda Hult maintains representation in ACI 522.
560 – ICF Buildings – The ACI 560 Committee will be commencing review and updates to its report publication, ACI PRC-560-22: Insulating Concrete Form Design and Construction. An update was provided on the status of NRMCA 100, Prescriptive Design of Exterior Concrete Walls for One- and Two-Family Dwellings, which is currently open for public comment. An update was also provided on the status of NRMCA and ICFMA’s joint project on NFPA 285 testing for insulated concrete form wall assemblies. Future committee work items include considerations for placement and consolidation of concrete in ICF walls and minimum horizontal reinforcement in ICF walls. Shamim Rashid-Sumar and Julian Mills-Beale maintain representation on ACI 560.
Concrete Research Council (CRC) – The Research Council of the ACI Foundation annually funds research programs. Task groups review and rank proposals based on several defined criteria. This year the CRC recommended funding four projects in materials and six projects in structures. Each proposal receives funding of $50,000 from CRC. Colin Lobo maintains representation on ACI CRC.
Other – Karthik Obla presented Improving Accuracy of the AI Model for Concrete Strength and Reducing Variability during a technical session. To celebrate the retirement of Bruce Suprenant, technical director of the American Society of Concrete Contractors, four sessions were organized with a wide range of technical presentations from friends and colleagues of Bruce. Colin Lobo was honored to be invited to present on Contractor and Producers: we CAN get along and outlined several technical and promotional activities on which NRMCA and ASCC worked together.
ACI Committee 242 has a new report ACI PRC-242-22: Alkali-Activated Cements. ACI’s Center of Excellence for Nonmetallic Building Materials (NEx) funded 12 projects in 2022 in four areas. At this convention, there were several sessions on low-carbon concrete showing increasing interest in this topic.
For more information, contact Karthik Obla at kobla@nrmca.org.
National Ready Mixed Concrete Association