NRMCA Reports on ACI 2013 Fall Convention

The ACI Fall Convention in Phoenix was held last week. NRMCA staff attended and is providing an update of some of activities that involved NRMCA representation.

NRMCA Staff Presentations – There were three technical sessions on recycled concrete. NRMCA’s Karthik Obla presented on the Sustainable Use of Crushed Concrete Aggregates in Concrete. NRMCA’s Colin Lobo presented on the Use of Recycled Water in Concrete. ACI provides access of many presentations made during the convention. 

130 – Sustainability Committee: The committee continues to struggle to finalize the Guide to Concrete Sustainability. The large scope of the document, size of the committee, special interests and rapid movement of the green building movement continue to hamper the development of this document. NRMCA’s Lionel Lemay worked to develop chapters on materials, production and construction, all of which have been balloted and finalized. The committee continues to take on additional responsibilities such as a new certification called Concrete Construction Sustainability Assessor. This program would be designed to assess an individual's knowledge of sustainable properties of concrete, including thermal mass, durability, pervious concrete, resilience, rating systems, carbon footprint, life cycle analysis, life cycle costing and other best practices. Lionel Lemay maintains representation on ACI 130.

132 – Responsibilities in Concrete Construction: ACI 132 is in the final stages of publishing a document that discusses the responsibilities of all stakeholders on a concrete construction project. It discusses associated responsibility with prescriptive and performance specifications. One last ballot was issued on revisions to the document and the committee spent its time resolving comments from this ballot. The revised document will be forwarded to the ACI review process (TAC review). After addressing comments from TAC, the document is expected to be published in Spring 2014. Colin Lobo maintains representation on ACI 132.

201 – Durability: The 201.2R Guide to Durable Concrete is being revised. All chapters have been completed – only the Introduction and Conclusion needs to be updated. NRMCA has provided input to this document. A Task Group (TG) is working on recommendations for physical salt attack. Recent NRMCA research findings will be provided to this TG. Karthik Obla maintains representation on ACI 201.

211 – Mixture Proportioning: Revisions to the document on concrete mixture submittals have been approved. NRMCA helped update this document which includes examples of prescriptive and performance submittals. Two new documents on mixture adjustments and mixture proportioning with ground limestone powder and mineral fillers have been approved and sent to TAC. NRMCA provided input to both documents. A task group is working on assessing aggregate gradings. Karthik Obla maintains representation on ACI 211.

214 – Strength Tests: This committee is collecting project compressive strength test data to update the table showing the standards of concrete control for both testing variability as well as batch to batch variability. A new future session is planned to discuss 4 x 8 in. and 6 x 12 in. cylinder test results and whether the ACI 318 requirement that three 4 x 8 in. cylinders constitute a test result (as opposed to only two 6 x 12 in. cyinders) needs to be revised. NRMCA is planning to participate in this session. NRMCA also pointed out the need for the committee to provide guidance on how concrete producers and contractors can calculate target average compressive strengths when faced with a PWL specification. PWL specifications attach incentives and penalties based on test results from sub lots and lots. Standard deviations are calculated based on sublot results. Karthik Obla is an associate member.

232 – Fly Ash and Natural Pozzolans: The committee has received TAC comments on a new report on high volume fly ash (HVFA) concrete and will ballot the responses and respond by the next convention. The committee is considering disbanding natural and processed pozzolans into a different committee due to the large number of such materials being increasingly used world-wide. The committee is involved in responding to the TAC suggestions on ACI 232.2R, Use of Fly Ash in Concrete. In the next convention the committee is sponsoring two sessions on Low Portland Cement Content Binders: Hydration and Properties. Karthik Obla is the Chair of ACI 232.  

301 – Specifications for Structural Concrete: ACI Committee 301 is working on several revisions to the specification in this cycle. Resolutions of ballots have resulted in revisions to the sections on lightweight concrete, mass concrete, shrinkage compensating concrete, architectural concrete, industrial floor slabs, precast and post-tensioned concrete, reinforcement and tilt up concrete. In the sections on concrete materials, Section 4, committee revisions will continue to evolve as resolution to ballots are completed. Several revisions have improved this section by eliminating unreasonable requirements. The committee is also working on including requirements for alkali silica reactions. The committee will review changes to ACI 318 as the reorganized code gets close to completion. The primary impact to ACI 301 will be the new ACI 318 chapter on Construction Document. ACI 301 is working toward completing its revised specification through the ACI review process (TAC and public review) by Spring 2015 and will continue to follow a schedule of bi-weekly Web conference calls to address resolution to ballots and revisions to the specification. Colin Lobo maintains representation on ACI 301.

318 – Building Code for Structural Concrete: The committee continues its frantic pace of achieving consensus on a reorganized member-based code. At this meeting all design chapters including commentary were completed. The last chapter that remains is the new chapter on Construction Documents. This chapter collects all items that the licensed design professional (engineer of record) needs to include in project specifications and drawings - resulting from the design and all code compliance items. The intent is to reiterate the concept that the Code is written to the licensed design professional and the contractor should not be responsible for Code requirements. These requirements should be stated in construction documents (specifications and drawings).

The generation of this chapter has resulted in elimination and simplification of several code provisions. It will cover requirements for concrete materials and mixtures, production, placing, curing, hot and cold weather concreting, strength acceptance criteria and inspection requirements. The final version of this chapter will be issued for ballot and resolved by December. The completed chapters will be forwarded for the ACI review process – TAC review. The schedule for completion of the revised ACI 318 is by Fall 2014 so that it can be referenced in the 2015 version of the International Building Code. Colin Lobo maintains representation on ACI 318.

325 – Concrete Pavements: The committee currently has five documents under development or revision. The report ACI 325.9R Guide for Construction of Concrete Pavements has been completely revised and the committee is currently responding to TAC comments. The committee has received tentative re-approval of ACI 325.12R-02: Guide for Design of Jointed Concrete Pavements for Streets and Local Roads which was revised by NRMCA's Brian Killingsworth, making U.S. Customary Units as primary and corrected the design thickness tables, while also addressing a few editorial issues. A complete revision with updated thickness tables and other technical revisions has begun and is being led by Killingsworth.

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 SHRP2 document has become the basis for an ACI design and construction report for precast and prestressed pavements which will be reviewed by the committee over the next few months. The committee is also developing ACI 325.YR Proportioning, Quality Control and Evaluation of Concrete Pavement Strength Relationships. The document is complete and has been balloted. Revisions to the document are being made based upon the ballot comments. A revision is underway of 325.11R Accelerated Techniques for Concrete Paving. Work is nearly complete and will be balloted in the next few months. The effort will harmonize with the proportioning document. 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.

327 – Roller-Compacted Concrete Pavements: Current activities include resolving TAC comments on the report ACI 327.XR Report on Roller-Compacted Concrete Pavements. The committee has also decided to hold off on development of an RCC specification for materials and construction to supplement report 327.XR until other specifications that are currently under development are completed and then reviewed by the committee. Brian Killingsworth maintains representation on ACI 327.

329 – Performance Criteria for Materials for Ready Mixed Concrete: ACI Committee 329 has completed its response to TAC comments resulting from the ACI review process. This final step will result in the publication of ACI 329R – Guide to Performance Requirements for Ready Mixed Concrete, in Spring 2014. The committee has revised its goals to permit it to develop a guide performance specification for concrete. It has requested permission from ACI to develop this type of document. It is envisioned that this document will provide recommended specification clauses and commentary advising the user on the reasoning and rationale. A primary goal will be to minimize prescriptive requirements and details on means and methods in project specifications. The committee will also provide information to ACI standards committees 301 and 318, suggesting performance-based alternatives to current requirements. The committee plans to develop a standard presentation discussing the benefits of evolving to performance-based specifications for improved quality and to support sustainable construction. 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." Four balloted chapters were reviewed, discussed and eventually approved. The committee will continue to ballot the remaining chapters and prepare for the document for the Technical Action Committee review. The committee also reviewed public comments on 330.1. Amy Miller maintains representation on Committee 330.

332 – Residential Concrete: The committee finalized the 2013 version of the Residential Code Requirements for Structural Concrete (ACI 332-13) and Commentary at this meeting by addressing public comments. NRMCA’s Lionel Lemay worked with the committee to significantly modify the section on durability that now follows more closely the durability requirements of ACI-318, Building Code Requirements for Structural Concrete. The residential code now has new definitions for durability classes, specifically for residential concrete to address freezing and thawing, sulfate and chloride exposure. Despite a more complex process for identifying mixture requirements for residential concrete as a result, the requirements for concrete mixtures remain similar to past versions of the residential code. The committee is currently developing a guide to simplify the process of identifying concrete requirements. Lionel Lemay maintains representation on ACI 332.

522 – Pervious Concrete: The 522 Committee completed a new revision to the specification, ACI 522.1, earlier in the year and the document has been published and is available. The committee is working on updating the accompanying guide. Several ballots were recently completed with more to come. Dr. Norb Delatte, Cleveland State University, discussed PervPave, a software from the American Concrete Pavement Association that allows for structural and hydrological design of pervious concrete. Dr. John Kevern, University of Missouri, presented research involving lightweight aggregates in pervious concrete. Dr. Narayanan Neithalath, Arizona State University, discussed research that evaluated structural efficiency of macro fibers in pervious concrete. As always, there was an update from liaisons in associated organizations: American Society of Civil Engineers, NRMCA’s Pervious Subcommittee, ASTM, Pervious Concrete Pavement Association and the Transportation Research Board. The meeting was finalized with Frank Kozeliski, New Mexico Promoter, presenting some job photos for a lively discussion. Amy Miller maintains representation 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. There is a lot of new interest in recycled concrete aggregate. Karthik Obla maintains representation on ACI 555.

• ACI has developed a new disaster reconnaissance committee (ACI 133) that will report on the effects of major disasters on concrete construction worldwide.

• An innovation task group (ITG-10) has been developed on alternative cementitious materials. ITG-9 was developed on concrete wind turbine towers.

• The following were recognized with awards at the ACI Opening Session: