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NRMCA Attends ACI Fall Convention, Updates Committee Activity NRMCA Engineeering Staff attended the ACI Fall Convention held November 7-11 in Denver. Below is an update of some of activities that involved NRMCA representation:
130 – Sustainability Committee - Progress on the guide to concrete sustainability is slow, but the document will be ready to go for technical review by Spring 2016. Lionel Lemay will continue to monitor this committee to ensure ready mixed concrete’s interests are maintained and performance specifications and life cycle assessment, including work at MIT, are properly described and acknowledged. Lemay maintains NRMCA representation on ACI 130.
201 – Durability - The 201.2R Guide to Durable Concrete is being revised. ACI review comments are being addressed. After some discussion, the committee decided to recommend that the chloride limits should be based on percent by weight of cementitious materials, which is commonly used in other national codes. The committee will recommend that ACI 318 should change its chloride limits for concrete exposed to moisture limit to 0.15% from the current 0.3%. A task group (TG) is working on a tech note for recommendations as well as test methods for physical salt attack. Future sessions are planned on the following: 1. Sulfate Attack; 2. Freeze Thaw Resistant Concrete; 3. Advances in Test Methods to Evaluate AAR; 4. Electrical Methods to Evaluate Mass Transport. Karthik Obla maintains representation on ACI 201.
211 – Mixture Proportioning - The committee has completed several documents in the last 1 year – Proportioning with Ground Limestone and Mineral Fillers; Guide to Troubleshooting Concrete Mixtures and Guide for Selecting Proportions for Pumpable Concrete. Two new task groups are working on 3-point curves and aggregate packing models. The main 211 proportioning document is being revised with input from NRMCA. Karthik Obla maintains representation on ACI 211.
214 – Strength Tests - The committee is developing tech notes on two topics - strengths of cubes vs cylinders and use of two 4x8 in. concrete cylinders instead of three for acceptance. Karthik Obla is an associate member.
232 – Fly Ash - The committee decided to work on a tech note on Guide to Specifying Fly Ash for Concrete Performance. The committee had submitted the ACI 232.2R, Use of Fly Ash in Concrete document for ACI review. The document has been tentatively approved. Karthik Obla will address comments on the chapter on specifications, tests, and quality assurance. His committee is organizing a session to honor Tarun Naik for his contributions. Additional sessions are planned on the use of ponded ash and beneficiated fly ash. Karthik is the vice chairman of this committee.
240 – Natural Pozzolans - This new committee on natural pozzolans continues to discuss whether to expand its scope and consider other supplementary cementitious materials like ground glass, rice hull ash etc. which are strictly not natural pozzolans. The lack of a specification for these types of pozzolans was also discussed. Karthik Obla maintains representation on ACI 240.
301 – Specifications for Structural Concrete - Following a 90-day period for public comments, ACI Committee 301 spent two days of meeting time to address about 350 public comments. Most editorial comments will be accommodated and approved. Several comments suggested substantive revisions that could not be addressed at this time and many of these will be addressed in the next cycle. The committee did, however, make some substantive changes to the specification based on comments received. The committee will convene for a few Web-based meetings to finalize its resolutions; it is anticipated that the new version of ACI 301 will be published in Spring 2016. The publication of the document will result in disbanding the committee and a new committee will be formed for the next cycle before the next ACI Convention. Colin Lobo maintains representation on ACI 301.
318 – Building Code for Structural Concrete - The code chapters of interest to concrete producers are Chapter 19 that states requirements for concrete, including the durability provisions, and Chapter 26 that includes provisions that the designer needs to include in construction documents. ACI 318 Subcommittee A on concrete materials have change proposals on the following:
325 – Concrete Pavements - The committee currently has seven documents under development or revision. The report ACI 325.9R Guide for Construction of Concrete Pavements has been completely revised and has been published. The committee is also rewriting ACI 325.12R-02 (Reapproved 2014): Guide for Design of Jointed Concrete Pavements for Streets and Local Roads and is being lead by Brian Killingsworth. Revisions to this document will be completed this winter and balloted in the spring. The committee is developing ACI 325.XR Report on Precast Concrete Pavements - State of the Practice which is based upon work completed by Tayabji for SHRP2. The committee is also developing ACI 325.YR Proportioning, Quality Control and Evaluation of Concrete Pavement Strength Relationships. The document is complete and is being prepared for publishing by ACI after some TAC comments are resolved.
A revision is underway of ACI 325.11R Accelerated Techniques for Concrete Paving. Work is nearly complete and will be balloted in the next few months. Work is also underway to update ACI 325.ZR: Design and Construction of Continuously Reinforced Concrete Pavements over the next year. Lastly, ACI 325.13R-06: Concrete Overlays for Pavement Rehabilitation is being reviewed and updated. This work will continue over the next year. Killingsworth will ensure that considerations for streets and local roads will be included in all documents. He maintains representation on ACI 325. 327 – Roller-Compacted Concrete Pavements - ACI 327R-14 Report on Roller-Compacted Concrete Pavements was recently published by ACI. It is intended for this document to replace ACI 325.10R-95: Report on Roller-Compacted Concrete Pavements (Reapproved 2001) at some point in the near future. The committee has also initiated development of an RCC specification for materials and construction to supplement report 327R-14. Brian Killingsworth maintains representation on ACI 327.
329 – Performance Criteria for Ready Mixed Concrete - The committee has established task groups and leads to develop a "Guide to Writing a Performance-Based Specification". It is anticipated that initial sections will be developed in the near future. The MasterSpec format will be used for this document so that it can be effectively used by practicing engineers. The new chairman, David Tepke, is soliciting new members to contribute to this effort. The committee has also developed a presentation that discusses the goal of performance-based specifications and the content of its guide report. ACI 329R-14. The committee is co-sponsoring upcoming sessions on performance-based specifications – Forum 123 at the next convention; performance-based alternatives to water-cement ratio; self-consolidating concrete and case studies on projects using performance specifications. Colin Lobo (secretary) and Karthik Obla maintain representation on Committee 329.
330 – Parking Lots - The ACI 330 Committee is completing the ACI 330X Guide to Design and Construction of Industrial Pavements. The task group discussed and reviewed committee members’ responses to comments from the ACI review. Amanda Hult represents NRMCA on Committee 330.
ACI 332 – Residential Concrete - The guide to residential concrete has been balloted and all negatives resolved and will be sent for technical review in Spring 2016. Lionel Lemay represents NRMCA on ACI 332, but Amanda Hult will be the representative from Spring 2016.
365 – Service Life Prediction - This committee is balloting changes to its State of the Art document on Service Life Prediction. NRMCA has provided input. Several sessions are planned at upcoming conventions. Karthik Obla is an associate member of this committee.
522 – Pervious Concrete - This committee is working through revisions to the 522R document and the specification. A report was provided on the pervious concrete competition that took place at the convention (49 teams – mix design reports due out soon). Amanda Hult represents NRMCA on ACI 522.
555 – Recycled Materials - The document Removal and Reuse of Hardened Concrete is undergoing revisions and will include discussions on crushed returned concrete aggregates based on research work conducted at the NRMCA Research Laboratory. Use of recycled concrete aggregate as unbound base will also be discussed. The committee continues to organize many technical sessions on the use of recycled materials in concrete at each ACI convention; each of these sessions are very well attended which underscores the importance of this topic. Karthik Obla maintains representation on ACI 555.
601B – Concrete Quality Technical Manager Certification - ACI has developed a new Concrete Quality Technical Manager (CQTM) certification program. Additional requirements for an ASME Level III Concrete Inspector have been added. The program has been launched; as a result this committee is dissolved and a new committee C 690 will take over this certification in time for the ACI Spring 2016 convention.
Technical Session - Two technical sessions were held on chloride limits for concrete. The different recommendations/requirements in ACI documents was discussed; the range of threshold chloride concentration to initiate corrosion in various research studies was presented and the contradictory benefits with the use of supplementary cementitious materials in concrete was discussed. The intent of the session was to evaluate whether chloride limits could be stated on the basis of cementitious materials as opposed to on the basis of cement as in the current ACI standards and guide documents. Colin Lobo presented to provide an industry perspective on chloride limits and summarized an informal survey of the industry. ACI will publish a special publication (SP) of papers from these sessions.
For more information, contact Colin Lobo at clobo@nrmca.org.
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