Engineering Staff Files Detailed Report from ACI Fall Convention

The American Concrete Institute's Fall Convention was held virtually from October 16 - 21; NRMCA Engineering Staff summarized relevant committee activity as follows:

122 - Energy Efficiency of Concrete and Masonry Systems – The committee is progressing with development of three new standards. One standard will provide guidance on dealing with thermal bridges in concrete and masonry structures. This standard has been approved for publication and is being proposed for inclusion in the International Energy Conservation Code. The other two standards provide the quantitative information required to model concrete and masonry building envelope components for use in building energy models for residential and commercial buildings and are in the review process. Scott Campbell maintains representation on ACI 122.

132 – Responsibilities in Concrete Construction – The committee completed a technical note on responsibilities associated with acceptance testing of concrete specific to care of test specimens at the jobsite; it is now in the ACI review process. It has also completed a new guide to responsibilities in concrete repair and rehabilitation that is also going through the review process. The committee has begun the process of revising its guide to responsibilities in concrete construction, ACI 132R. It selected some topics on responsibility for future conventions, primarily who bears responsibility for concrete cracking. Colin Lobo maintains representation on ACI 132.

201 – Durability – The committee is revising the guide to durable concrete, 201.2R. Chapter 9 on Corrosion is being updated with discussions on proposing modifications to ACI 318 exposure classes and concrete requirements that includes prescriptive and alternative performance requirements. The guide will also address Microbial Induced Corrosion (MIC) of Concrete. The committee is balloting a Tech Note (TN) on iron sulfide minerals in aggregate, specifically Pyrrhotite. A new document on alkali aggregate reactions is being developed jointly with Committee 221 on Aggregates. A session on Pyrrhotite is planned for the April 2022 convention. Karthik Obla maintains representation in ACI 201.

211 – Mixture Proportioning – The committee is addressing TAC comments (ACI review process) to its primary document on mixture proportioning (ACI 211.1). A document on developing 3-point curves for trial batches is being reworked. Task groups are addressing comments received on the new ballot on assessing aggregate gradations. A task group is working on a new report on aggregate packing models. Karthik Obla maintains representation on ACI 211.

214 – Strength Tests – The committee will not develop a Tech Note on using two instead of three 4x8 in. cylinders for acceptance testing since there is a change proposal regarding this in ACI 318. The committee is finalizing Tech Notes on cylinder vs cube strengths and to establish guidance on establishing required average strength for different risk levels relative to the ACI acceptance criteria. The committee will develop a new TN on “When a test specimen result can be discarded”; a new report on developing acceptance criteria based on statistical concepts for specified tests other than strength, such as for flexural strength, modulus of elasticity, RCP, resistivity, and w/cm measured using the microwave oven. The 214R document is being revised; the basis for modification factors for standard deviation based on less than 30 tests will be outlined. The committee will propose a definition for strength over-design. Karthik Obla maintains representation on ACI 214.

216 – Fire Resistance and Fire Protection of Structures – The ACI 216 Committee continues to finalize the revised edition of ACI 216.1, Code Requirements for Determining Fire Resistance of Concrete and Masonry Construction Assemblies. This updated edition of the standard will include 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 will provide guidelines for determining fire resistance through analytical methods in addition to the existing prescriptive methods. The technical committee has also developed a new chapter on post-fire assessment and repair in ACI 562, Code Requirements for Assessment, Repair, and Rehabilitation of Existing Concrete Structures. Shamim Rashid-Sumar maintains representation on ACI 216.

232 – Fly Ash – The committee is finalizing its response to TAC comments to finalize the TN on potential use of harvested fly ash from impoundments. Future sessions are planned on the use of bottom ash as an SCM. There was an update on the various research projects addressing fly ash supply. Karthik Obla maintains representation on ACI 232.

301 – Specifications for Structural Concrete – The subcommittee responsible for Section 4 on Concrete Mixtures is working on a significant reorganization to consolidate and categorize submittals and other revisions that have been identified. The subcommittee responsible for post tensioned systems in Section 9 will separate provisions for bonded and unbonded PT construction. The committee sponsored two sessions where the changes to 301-20 from the previous versions were summarized by the subcommittee chairs. Recordings of these sessions will be available on the ACI website. The committee is working on a revision to the ACI 301 specification to be published after 2025. Colin Lobo maintains representation on ACI 301.

318 – Building Code for Structural Concrete – ACI Subcommittee A on Concrete Materials is working on several code change proposals. Approved items include a reference to specification for ground glass pozzolans, a requirement to verify consolidation in ICF construction and clarification on chlorides in admixtures for prestressed concrete. Other change proposals in progress include the ability to use two 4x8 in. cylinders for a strength test, addressing criteria for field cured specimens for post tensioning and formwork, including additional requirements for hot and cold weather concreting; enhancing requirements for curing; permitting the designer to exempt the limits on SCMs for exposure class F3; revising chloride exposure class to include air-borne chlorides for structures close to the ocean; the acceptance process for density of lightweight concrete to include a performance requirement based on ASTM C1202 instead of a limit on w/cm and several other changes. Frank Malits takes over as chair of 318A from Terry Holland who served as chair for several years.

Subcommittee N on Sustainability is finalizing a new appendix on sustainability to ballot at the main committee. 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, concrete materials for reduced environmental impact and system resilience. Colin Lobo maintains representation on subcommittees A and N and on the 318 main committee.

321 – Concrete Durability Code – ACI 321 is a new committee formed last year to develop a code for durability. The committee has developed more detailed exposure classes than currently defined in ACI 318 and is working to finalize these before establishing requirements for concrete. Requirements for concrete will include both prescriptive and performance alternatives. This code could be referenced for structures beyond buildings that is covered by ACI 318.

325 – Concrete Pavements – 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 Brian Killingsworth. Revisions to this document have been completed and are currently being balloted. 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 SHRP2. 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 will be balloted this winter. Killingsworth will ensure that considerations for streets and local roads will be included in all documents. Brian Killingsworth maintains representation on ACI 325 on Concrete Pavements.

329 – Performance Criteria for Ready Mixed Concrete – The committee did not meet but has different sections for a guide performance specification in progress. Karthik Obla and Colin Lobo maintain representation on ACI 329.

330 – Parking Lots – The committee is addressing comments from the ACI review process on the 330.1 specification. The committee is working on addressing construction tolerances. Amanda Hult maintains representation in ACI 330.

332 – Residential Concrete – The research funded by the Ready Mixed Concrete Research & Education Foundation at the University of Washington was presented to the above grade wall subcommittee. A proposal for development of three ACI Tech Notes demonstrating the use of less reinforcement in concrete walls was presented and the committee is conducting an online ballot regarding moving forward with that development. Scott Campbell maintains representation on ACI 332.

380 – Plain Concrete – A proposal for development of three ACI Tech Notes demonstrating the use of less reinforcement in concrete walls was presented and the committee voted to move forward with that development. Scott Campbell maintains representation on ACI 380.

522 – Pervious Concrete – The committee continues to address TAC comments on the 522R guide document. Amanda Hult maintains representation in ACI 522.

555 – Recycled Materials – ACI’s TAC has advised the committee to split the existing document into three reports: removal of hardened concrete, reuse of hardened concrete and unbound recycled concrete applications. The committee continues to work on these documents. Karthik Obla maintains representation in ACI 555.

560 – ICF Buildings – A technical mini-session with excellent attendance was presented during the committee meeting by Scott Campbell and Micah Garret. The committee has finalized its guide document update of example problems and is working through the approval process. A proposal for development of three ACI Tech Notes demonstrating the use of less reinforcement in concrete walls was presented and the committee voted to move forward with that development. An update on relevant code changes from the 2021 ICC hearings was presented. Scott Campbell and Shamim Rashid-Sumar maintain representation on ACI 560.

Concrete Research Council (CRC) – The Research Council of the ACI Foundation funded eight research projects – four in materials and four in structural design – in its 2021 cycle. The council discussed sources of funding for the 2022 cycle and it is likely the same number will be selected at the same funding level of $50,000 each. Research proposals will be solicited soon. The committee finalized its selection of recipients for the 2022 Robert E. Philleo and Boase awards to be presented at the next ACI Convention. Colin Lobo maintains representation on ACI CRC.

For more information, contact the relevant NRMCA staff member listed at the end of each committee report.