Bruce Suprenant, Technical Director, The Voice Newsletter December 2017 ACI 306R-88, “Guide to Cold Weather Concreting”, addressed multiple cycles of freezing and thawing by recommending that the concrete reach a compressive strength of 3500 psi prior to that exposure. ACI 201-77, “Guide to Durable Concrete”, also addressed the issue by stating: “Before being expos...

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Bruce Suprenant, Technical Director, The Voice Newsletter November 2017 Ward Malisch answered this question about welded wire reinforcement (WWR) tolerances in the October 2010 VOICE. Since then the answer has changed. See both the 2010 and the 2017 answers below. QUESTION: What is the tolerance for deflection in 2.9x2.9, 2.0x2.0, and 1.4x1.4 welded-wire reinforcement (WWR) that is specified...

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Bruce Suprenant, Technical Director, The Voice Newsletter October 2017 A lot has happened within CPC in the short time from May Committee Days in St. Louis to the September Annual Conference in Phoenix. What started in May got kicked around and discussed in depth in Phoenix: slab and polishing contractors working together on documents. At the Annual Conference, there were two roundtable discuss...

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Bruce Suprenant, Technical Director, The Voice Newsletter September 2017 When rain falls on fresh concrete, concrete contractors get blamed for not checking the weather conditions and not planning the concrete placement to avoid rain. But tell that to concrete contractors in Seattle or Miami. The rainy season in Seattle includes six months, October through March, with15 days of rain or more, pl...

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Bruce Suprenant, Technical Director, The Voice Newsletter June 2017 The ACI-ASCC 117 Tolerances Committee has just established a subcommittee to consider the effect of movements on tolerances. The current ACI 117-15 does consider the effect of some movements on tolerance measurement. It considers time, within 72 hours, in measuring flatness and levelness either by F-numbers or a 10-ft. straight...

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Bruce Suprenant, Technical Director, The Voice Newsletter ACI’s Technical Activities Committee (TAC) forms technical committees and assigns each a mission. A technical committee mission identifies the knowledge area the committee is responsible for and is usually not document specific. Thus a single committee could develop both a Code or Standard and also a Guide. For instance, ACI Commit...

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Bruce Suprenant, Technical Director, The Voice Newsletter February 2017 Yes, this is concrete at my house in Boulder, CO. Photos A and C are of the “new” concrete placed in 1992. Photo B is the “old” driveway placed in 1967. I bought the house in 1988 so I am responsible only for the “new” concrete. Well sort of. Let’s start with Photo A. There&rs...

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Bruce Suprenant, Technical Director, The Voice Newsletter October 2016 ACI 301-16 “Specifications for Structural Concrete” adopted a new provision for initial curing of flatwork. This provision will increase the cost of performing work for concrete that does not bleed enough to show a visible water sheen. The new provision is shown below: 5.3.6.2 Initial curing of unformed concre...

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Ward Malisch, Concrete Construction Specialist, The Voice Newsletter, September 2016 Have you seen or heard of any requirements for formed concrete surface quality in bid packages? They might be in the form of a reference to ACI 347.3R-13, “Guide to Formed Concrete Surfaces,” in specifications based on models such as AIA MasterSpec™. Sometimes specifications other than AC...

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Bruce Suprenant, Technical Director, The Voice Newsletter July 2016 Shrinkage and temperature reinforcement requirements for design of reinforced concrete structures have been included in the ACI building code since 1928, and haven’t changed much in nearly 85 years. The ACI 318-14 Commentary states that the amounts of shrinkage and temperature reinforcement specified for deformed bars and...

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