The American Concrete Institute's Spring Convention was held late last month in Detroit. NRMCA Engineering Staff provided the following update of some activities that involved NRMCA representation:

NRMCA Recognized by ACI - ACI recognized NRMCA with the Henry C. Turner Medal. The recognition is for extraordinary support of the concrete industry through commitment to professional development, promotion and partnering. 

130 – Sustainability Committee - The Committee continues to work on its document on concrete and sustainability. All the additional TAC comments received previously in 2016 were addressed and balloted. The chapter on end of use phase was balloted in January 2017 and all the negatives were resolved at the meeting. There will be an additional deconstruction section for the end of use phase to resolve a negative. One section remains to be written: climate change/resilience and two sections updated: introduction and conclusion. Julie Buffenbarger chairs this committee.

132 – Responsibility in Concrete Construction Committee - The committee agreed to ballot a Tech Note that will discuss responsibilities related to acceptance testing at the jobsite. There are some inconsistencies within ACI documents on who is responsible for the curing box. The committee agreed to communicate to ACI 318 on the need for including the durability exposure class in construction documents (currently it is optional). Other Tech Note topics discussed by the committee included Mixed Modes of Specification and Durability vs. Serviceability. Lastly, the committee will be publishing an SP in conjunction with ACI 522 Repair Committee. These documents will be the basis of updating the current committee document to include repair. Julie Buffenbarger (secretary) and Colin Lobo maintain representation on ACI 132.

201 – Durability - The committee has completed the new 201.2R-16 Guide to Durable Concrete. A task group (TG) is working on two Tech Notes on repair of structures affected by physical salt attack and recommendations for mitigating physical salt attack in new construction. Other TGs are working on tech notes on joint deterioration due to deicers. The committee is considering creating a mandatory language durability specification that can be invoked. Karthik Obla maintains representation on ACI 201.  

211 – Mixture Proportioning - The committee is working on resolving negatives on several chapters of the ACI 211.1 document. Task groups are developing chapters on 3-point curves for trial batches and assessing aggregate gradations. Karthik Obla maintains representation on ACI 211.

214 – Strength Tests - The committee is working on a revision to the 214R document. The draft will contain discussions on percent within limit specifications and will address calculating target averages for flexural strength, RCPT and elastic modulus when these properties are specified. Karthik Obla maintains representation on ACI 214.

232 – Fly Ash - The committee has addressed all the TAC comments and will send the revised document ACI 232.2R, Use of Fly Ash in Concrete to TAC. The committee will ballot a Tech Note based on the NRMCA Specification in Practice topic titled Restriction in SCM Contents. Karthik Obla is the vice chairman of this committee.

234 – Silica Fume - The Silica Fume Committee will be creating a special publication based upon the works of Per Fidjestol. It will be published in 2018. The committee continues to work on revising its document on guidance with the use of silica fume. In the revision, additional chapters will cover ternary blended cements with silica fume, self-consolidating concrete and sustainability.

240 - Pozzolans - This committee will report on all materials that demonstrate pozzolanic properties but do not comply with ASTM C618 or C1240, such as ground glass, rice hull ash, etc. It was pointed out that some high alkali glass pozzolans may meet C1567 but may not meet C1293 or C441. It would be useful to point that out in the ASTM specification on ground glass. Karthik Obla maintains representation on ACI 240.

301 – Specifications for Structural Concrete - The committee is working on revisions for the next version of ACI 301 scheduled to be published in 2020. The steering subcommittee devoted some time toward a strategic plan for the specification as it evolves. Revisions currently in progress impact Section 1 on general requirements, Section 2 on formwork and Section 3 on reinforcement. Revisions being considered for Section 4 on concrete mixtures include alkali aggregate reactions, including options for internal curing and the use of mineral fillers, including shotcrete, addressing maximum limit on air content for floors, delivery restrictions for time, initial curing of strength test specimens, considerations for self consolidating concrete and simplifying temperature limits for delivery of concrete. Colin Lobo maintains representation on ACI 301.

318 – Building Code for Structural Concrete - ACI 318 is scheduled to be published in 2019 and the committee has about three meetings to complete its revisions. There are various code change proposals in progress on the design section of the Code.

ACI 318 Subcommittee A on Concrete Materials has change proposals on the following: improving clarity on the definitions and requirements for strength tests (approved by 318); permitting the calculation of chlorides in lieu of testing (approved); expressing chloride limits on the basis of cementitious materials as opposed to cement only; permitting the use of mineral fillers; simplifying the determination of lambda used in design for lightweight concrete; including a new option for sulfate resistance of concrete while permitting the use of cements containing limestone (ASTM C595) when sulfate exposure is expected; adding provisions that will permit the use of shotcrete; addressing the use of recycled aggregate in concrete and addressing conditions where the designer would consider specification for alkali silica reactions.

 

The subcommittee is also working on code change proposals for consideration of performance-based alternatives to w/cm ratio, including a provision to test for elastic modulus on the proposed mixture (in the submittal phase); revising the inspection provisions for concrete to be consistent with the International Building Code and addressing the use of performance-based cements that conform to ASTM C1157. A change proposal addresses sampling at the point of placement with advisory information to the designer when this is specified. A task group is also undertaking a thorough review with ACI 301 of the requirements in Chapter 26 that needs to be included in specifications. Colin Lobo maintains representation on ACI 318 and ACI 318 Subcommittee A.

325 – Concrete Pavements - NRMCA’s Brian Killingsworth maintains representation on ACI 325 on 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 and is being lead by Killingsworth. Revisions to this document will be completed this spring and balloted in the fall. 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 has developed ACI 325.YR Proportioning, Quality Control and Evaluation of Concrete Pavement Strength Relationships will be published by ACI in the next few months. 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 few months. 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.

329 – Performance Criteria for Ready Mixed Concrete - The committee’s primary objective is to develop a Guide to Writing a Performance-Based Specification. An outline has been developed and task groups have begun developing the chapters using the MasterSpec format so that it can be effectively used by practicing engineers. The committee discussed various test methods and their use, followed by an evaluation of different concrete member types and the potential performance properties that could be specified. The Tech Note based on NRMCA Specification in Practice regarding the inclusion of minimum cementitious materials content in specifications has been approved. The committee is also completing a presentation that discusses the goal of performance-based specifications and the content of its guide report, ACI 329R-14. The committee discussed sponsoring technical sessions at future conventions and identified a few potential topics. Colin Lobo (secretary) and Karthik Obla maintain representation on Committee 329.

330 – Parking Lots - The ACI 330 Committee is currently revising 330R-08. The 330.2R-17: Guide for the Design and Construction of Concrete Site Paving for Industrial and Trucking Facilities is ready for publishing and should be in circulation this summer. Amanda Hult represents NRMCA on Committee 330.

555 – Recycled Materials - The document Removal and Reuse of Hardened Concrete is being revised to include a section on crushed concrete aggregates from returned concrete based on research work conducted at the NRMCA Research Laboratory. Two chapters were balloted and the meeting was used to resolve negatives. The committee continues to organize many technical sessions on the use of recycled materials in concrete at ACI conventions due to the continued interest on these topics. Karthik Obla maintains representation in ACI 555.

C601-0E Concrete Construction Sustainability Accessor - The Sustainability Accessor Certification should be ready for beta testing in Spring 2018. The certification program covers multiple areas of sustainability, including materials, LCA, LCCA, climate change and resilience. The course has been approved by staff. The initial testing materials have been selected. Questions for the exam continue to be developed. Julie Buffenbarger maintains representation on C601-E.

S801-Eco-Concrete Student Competition - A new student competition is being finalized for ACI by members of ACI 130. The course will include LCAs and LCCA on materials and construction. The competition will be instituted in Spring 2018. Julie Buffenbarger maintains representation on S801.

Two technical sessions on Case Studies of Performance-Based Specifications of Concrete were moderated by Karthik Obla. An article compiling the case studies is planned. 

There was a Forum on 3D printing. Possible applications include elimination of need for form work. The formwork will be 3D printed on site. Various fresh properties such as extrudability, buildability, pumpability, flowability, shape stability etc. were discussed. The technology is still nascent but the next ACI convention will feature two technical sessions. There was a session on Electrical Methods to Evaluate Mass Transport.

A new technical committee has been formed on constructability.

The Concrete Research Council (CRC) has assigned funding of $50,000 each for four projects for 2017. The solicitation received 38 proposals that have been narrowed down to six projects. The council will select four projects – two on materials and two on structural design – for award.

 

A previously funded CRC project is assimilating the variations on recommendations and requirements for durability in ACI committee documents and standards. The group is evaluating the basis and attempting to harmonize these requirements that would be consistent in ACI Documents. Colin Lobo maintains representation on ACI CRC. 

An article was completed for the February 2017 edition of Concrete International previously by Julie Buffenbarger and Koji Sakai, co-moderators of the annual forum. Planning continues for the 10th annual Sustainability Forum which will be held in Anaheim, CA, at the Fall Convention. Presently, confirmed speakers include presidents from fib, RILEM, ACI, ACI 130 (Julie Buffenbarger) and the Japanese Institute of Concrete (Koji Sakai). Invitations have also been sent to Cement Sustainability Initiative, Carbon Cure and one additional entity. Coordination of the event will continue throughout the coming months. Julie Buffenbarger remains as coordinator and moderator of this event.