NRMCA Attends ACI Fall 2016 Convention; Updates Key Issues

The ACI Fall Convention was held October 22-26 in Philadelphia. Below is an update of some of the activities that involved NRMCA representation:

130 – Sustainability Committee: The Technical Activities Committee approved the materials document from ACI 130. Comments received by TAC were addressed and over half balloted. Additional comments and changes will be committee- member balloted over the next two months. One additional chapter for the ACI 130 document on sustainability was completed over the summer; the glossary. Four sections remain: end of use phase, climate change/resilience, introduction and conclusion. Julie Buffenbarger maintains representation on ACI 130.

132 – Responsibilities Committee: The committee continued working on a chapter on responsibilities for repair of concrete construction in its document 132R. The committee again discussed responsibilities related to testing at the jobsite between the contractor and the testing agency. Discussions related to access, space, power, initial curing and care of test specimens were primary focus. A draft of a tech note on this topic was presented to the committee and will be balloted. Other Tech Note topics discussed by the committee included Mixed Modes of Specification and Durability vs. Serviceability. Julie Buffenbarger (secretary) and Colin Lobo maintain representation on ACI 132.

201 – Durability: The committee has addressed TAC comments to the revised 201.2R 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. A TG has been created to look into creating a mandatory language durability specification that can be invoked. The TG will present its findings by the next convention. Future technical sessions being organized by the committee include Electrical Methods to Evaluate Mass Transport. 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 tech notes on 3-point curves for trial batches and assessing aggregate gradations. Karthik Obla maintains representation on ACI 211.

214 – Strength Tests: The committee discussed ballot response to the two tech notes - strengths of cubes vs cylinders; and use of two 4x8 in. concrete cylinders instead of three for acceptance. The tech note on Cubes vs Cylinders will be redrafted. The committee seeks more data to evaluate the difference in variation between 4x8-in. and 6x12-in. cylinders. Karthik Obla maintains representation on ACI 214.

232 – Fly Ash: The committee is working on changes in response to TAC review of the document ACI 232.2R, Use of Fly Ash in Concrete. The committee will develop a draft tech note based on the NRMCA Specification in Practice topics that pertain to fly ash. Future technical sessions are planned on Recovered and Beneficiation of Fly ash. Karthik Obla is the vice chairman of this committee.

234 – Silica Fume: The committee continues to work on revisions to its document on guidance with the use of silica fume. In the revision, chapters will cover self-consolidating concrete and sustainability.

240 – Natural Pozzolans: This committee continues to debate its name and mission statement. The current approach seems to change the name to Pozzolans and report on all materials that demonstrate pozzolanic properties, but does not comply with ASTM C618 or C1240, such as ground glass, rice hull ash, etc. Karthik Obla maintains representation on ACI 240.

301 – Specifications for Structural Concrete: ACI 301-16 has been published. The revised specification has made some important revisions that move it more toward performance and is consistent with the requirements in the ACI 318-14 Building Code.  Some revisions being considered include internal curing options, max w/cm for durability to apply to lightweight concrete, revisions to the mass concrete section and issues that will require an update to a thermal control plan, submittal of stressing records for post-tensioned concrete and addressing responsibility of the contractor for initial curing of test specimens. The committee partnered with ACI 318A on a session to outline the relationship between ACI 301 and 318 Ch 26. 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: clarifying acceptance requirements for strength; remove a reference to ACI 301 for proportioning concrete; requiring testing technicians to be certified (change from qualified); permitting the calculation of chlorides in lieu of testing for conformance to chloride limits; stating the basis of chlorides on the basis of total cementitious materials (as opposed to only cement); reducing the chloride limits for concrete dry in service; adding provisions for alkali silica reactions; evaluating data to consider permitting 2 (instead of 3) 4 x 8 inch cylinders for strength tests; and clarifying that water and admixtures do not have limits on chlorides, while cautioning on the potential corrosion of aluminum embedments and galvanized steel.

 

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, defining the lambda-factor for design with lightweight concrete based on equilibrium density, and alternative options for sulfate resistance. A proposal will include provisions for shotcrete in the code. Also considering whether to permit the use of recycled aggregate and alternative cements for structures built to ACI 318. The committee 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 Subcommittee 318A.

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 has finalized a tech note based on NRMCA Specification in Practice regarding the inclusion of minimum cementitious materials content in specifications. 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 will sponsor a session on Case Studies (chaired by Karthik Obla) at spring ACI convention in Detroit. Colin Lobo (secretary) and Karthik Obla maintain representation on Committee 329.

330 – Parking Lots: The ACI 330 committee has started the revision of 330R-08 document. Revision will include the removal of the heavy duty design information which is included in the 330X Industrial document. Comments should be completed by spring meeting. Amanda Hult represents NRMCA on Committee 330.

522 – Pervious Concrete: The 522R document is currently in for TAC review.  Comments will be addressed at the spring meeting. Comments are still being accepted for sections in ACI 522.1-13. Amanda Hult maintains representation on ACI 522.

555 – Recycled Materials: The document Removal and Reuse of Hardened Concrete is being revised and includes 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 Fall 2017. 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 are being developed.

S801-Eco-Concrete Student Competition: A new student competition is being completed 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 2017.

Three technical sessions were held on sulfate attack. Karthik Obla presented NRMCA research on physical salt attack and Colin Lobo presented the portion on chemical sulfate attack.

An Innovative Task group (ITG-10) on Alternative Cements is developing a state of art report.

An ad hoc group of impacted parties from CT, ACI committees, researchers and representatives from PCA, NRMCA and Concrete Foundations Association (CFA) met to discuss residential concrete basement deterioration in Connecticut. The group will develop a basic information item and identify committees that will develop technical information relative to deterioration caused by the mineral pyrrhotite in aggregates. Information from Canada, Europe and other locations will be compiled.

Eight speakers were included in the 9th Sustainability Forum moderated by Koji Sakai, Japan Sustainability Institute; and Julie K. Buffenbarger, NRMCA. Forum topics included Roadmap Toward Realization of Sustainable Concrete Structure, Koji Sakai, Japan Sustainability Institute; The Envision Rating System for Sustainable Infrastructure, Denise Nelson, Institute for Sustainable Infrastructure; The Direct Carbonation of Ca(OH)2 Using Liquid and Supercritical CO2: Implications on Carbon-Neutral Cementation, Gaurav N. Sant, University of California, Los Angeles; Efforts of Japanese Construction Industry to Use Low-Carbon Concrete, Mamoru Yamada, Obayashi Company; Low-CO2 Eco Efficiency Cement-Based Materials - A Report from UNEP SBCI Working Group, John Vanderley, University of São Paulo; The MIT Concrete Sustainability Hub: Transforming Innovation into Implementation, Jeremy Gregory, Massachusetts Institute of Technology; Toward the Sustainable Built Environment in Philadelphia, Alex Dews, U.S. Green Building Council Delaware Valley Chapter.