NRMCA Engineering Staff Attends ACI Spring 2019 Convention, Updates Key Ready Mixed Concrete Committee Activity
The American Concrete Institute's Spring Convention was convened in Quebec City the week of March 24. The following is a summary of committee activity involving NRMCA Staff representation:
122 – Energy Efficiency of Concrete and Masonry Systems – The committee is progressing with development of two new standards. One standard will provide guidance on dealing with thermal bridges in concrete and masonry structures. This standard is designed to provide an alternative to ASHRAE 90.1 requirements, which are unfavorable to the industry and contain details that cannot be constructed. The other standard will provide the quantitative information required to model concrete and masonry building envelope components for use in building energy models. Scott Campbell maintains representation on ACI 122.
132 – Responsibility in Concrete Construction – Work is ongoing for a special publication and document to address responsibility associated with repair of concrete structures. The committee will review the responsibilities of the designer as it relates to addressing requirements in construction documents in ACI 318 Building Code (Chapter 26). The existing responsibilities document, ACI 132R, will be reviewed for revision through a balloting process. The committee discussed the responsibilities associated with acceptance testing of concrete. Options included addressing this in more detail in the current committee’s document or developing these responsibilities in a mandatory language standard that could be referenced by other codes and specifications. The latter would require restructuring the membership of the committee to write standards. A concept amendment related to acceptance testing of concrete proposed for the Pennsylvania building code was presented. Colin Lobo maintains representation on ACI 132.
201 – Durability – The committee is completing three Tech Notes that are in various stages of approval: 1) Joint deterioration due to deicers; 2) Iron sulfide (Pyrrhotite) in Aggregates; and 3) Microbial Induced Corrosion (MIC) of Concrete. Karthik Obla chairs a task group considering performance requirements for ACI 318 durability exposure classes. The committee will ballot a code change proposal that will require RCPT as the performance alternative for chloride exposure class C2.
Committee 201 has established task groups to develop code requirements for durability, initially considering provisions in existing codes such as ACI 318 and 350, and to develop a specification document supporting this code. It is anticipated that these documents could be referenced by existing ACI standards. The committee is developing a review paper on physical salt attack as well as a joint report on alkali-aggregate reactivity with the ACI Aggregates Committee. The committee is collecting papers for two special issues of ACI Materials Journal on Durability in 2019: one on chlorides and corrosion and another on SCMs. Karthik Obla is the joint editor for the chlorides special issue. Karthik Obla maintains representation on ACI 201.
211 – Mixture Proportioning – The committee continues its work on revising its primary document on mixture proportioning ACI 211.1. A document on developing 3-point curves for trial batches had been approved by the committee. Task groups are developing documents on assessing aggregate gradations and aggregate packing models. ACI review comments have been addressed on the document on proportioning with ground limestone and mineral fillers. Karthik Obla maintains representation on ACI 211.
214 – Strength Tests – The committee is working on a revision to the 214R guide document. The committee has approved revisions to 214.4R, Guide to Core Tests, and has been submitted for the ACI review process. A Tech Note “Using two instead of three 4x8 in. cylinders for acceptance testing” is being held in response to the ACI review process. The committee has completed a Tech Note on cylinder vs cube strengths. Karthik Obla will present a concept for a new Tech Note on developing specification criteria and target values for properties other than compressive strength. Karthik Obla maintains representation on ACI 214.
232 – Fly Ash – The committee has assigned individuals chapters to rewrite the ACI 232R document. The committee has developed a Tech Note on limits on the quantity of fly ash in specifications based on an NRMCA Specification in Practice topic and is being revised following ACI review. A Tech Note on harvesting fly ash is being finalized. A new ASTM guide (E3183-18) for Harvesting Coal Combustion Products in Active and Inactive Storage Areas for Beneficial Use is available. Legislative actions in North Carolina and Virginia will likely support the potential availability and use of harvested fly ash in the near future. Karthik Obla is the vice chairman of this committee.
240 – Pozzolans – A Tech Note on pozzolans derived from ground glass is being developed. The committee discussed establishing requirements in the ASTM standards to prevent the use of materials that are not pozzolanic. Options including changing strength activity index to 80%, adding new pozzolanic reactivity tests based on lime reactivity or bound water or using the resistivity test to indicate continued reactivity. The natural pozzolan association has organized a symposium on May 16-17 in Wickenburg, AZ. More information is available at http://pozzolan.org/. Karthik Obla maintains representation on ACI 240.
301 – Specifications for Structural Concrete – With all revisions to the specification being completed, the committee devoted time for a thorough editorial review and ensured that all ballot items in this cycle had been resolved. The specification will be submitted to the ACI review process, followed by a public comment period. The committee has made several revisions to the specification in this cycle and has ensured that relevant revisions to ACI 318 have been addressed in ACI 301. It is anticipated that ACI 301 will be published in summer of 2020. Colin Lobo maintains representation on ACI 301.
318 – Building Code for Structural Concrete – This was the last meeting for the cycle for ACI Committee 318. The meeting was dedicated to responding to more than 500 public comments received as part of the process of finalizing the code. The code has been finalized and will be published shortly so that it can be referenced in the next edition of the International Building Code. For concrete materials sections in Chapters 19 and 26, about 40 change proposals have been approved. A summary of the more significant changes will be developed when ACI 318-19 is published. A new committee is being formed for the next cycle. Colin Lobo maintained representation on ACI 318 and ACI 318 Subcommittee A for this past cycle.
329 – Performance Criteria for Ready Mixed Concrete – The committee approved an introductory chapter on the guide performance specification through a balloting process. The guide specification will use the AIA MasterSpec section 033000 on cast-in-place concrete to propose specification language and additional guidance information that will minimize prescriptive requirements and propose performance alternatives. The initial drafts of these sections have been developed and are being reviewed before being balloted. A separate chapter will outline the various performance test methods and how they can be used to qualify and accept concrete mixtures. Colin Lobo (secretary) and Karthik Obla maintain representation on Committee 329.
330 – Parking Lots 301 – The ACI 330 Committee continues to work on revising its guide document ACI 330R. Each chapter has been balloted and comments were addressed during this meeting. The complete document is working through the ACI review process. Amanda Hult maintains representation on ACI 330.
522 – Pervious Concrete –The committee is currently revising the ACI 522R specification. The specification will be sent shortly for ballot. Publication date is about a year out. The education subcommittee is revising the rules for future student competitions. The next pervious concrete student competition is scheduled for 2021. Amanda Hult maintains representation on ACI 522.
555 – Recycled Materials – The committee is revising its document Removal and Reuse of Hardened Concrete to include a section on crushed concrete aggregates from returned concrete based on research work conducted at the NRMCA Research Laboratory. NJIT maintains a database of research on recycled concrete aggregates in concrete. Karthik Obla maintains representation on ACI 555.
• A Hot Topic Session discussed the issue of alkali-aggregate reactivity. One of the presentations was on the issue of pyrrhotite in aggregates that have been identified in some aggregate sources in Quebec province and Connecticut and have resulted in deteriorated concrete, primarily residential foundations. Researchers are proposing considerably involved testing of all aggregate sources. These tests have yet to be standardized.
• ACI will change its Contractor Day event to architects/engineers in order to attract and target specific information to architects and engineers.
• ACI Concrete Research Council (CRC) has approved funding for six research project proposals for 2019. The projects are split between materials and structures research topics. These projects were selected from 40 proposals with funding at $50,000 for each project. The projects should demonstrate the benefit of their work to the work of ACI committees. The ACI CRC partners with the RMC Research & Education Foundation and foundations of allied industry groups. Colin Lobo maintains representation on ACI CRC.