Concrete Products

MAR 2016

Concrete Products covers the issues that attract producers of ready mixed and manufactured concrete focusing on equipment and material technology, market development and management topics.

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Page 26 of 75 March 2016 • 25 NEWS SCOPE BY DON MARSH American Concrete Pipe Association (ACPA) and BASF Corp. (Admixture Systems) officials joined University of Texas at Arlington Struc- tural and Applied Mechanics Professor Seyeda- li (Ali) Abolmaali for a World of Concrete 2016 presentation on how a new ASTM Committee C13 on Concrete Pipe standard positions dry cast structures more competitively against less robust drainage alternatives. The committee published ASTM C1818-15 Standard Specification for Rigid Synthet- ic Fiber Reinforced Concrete Culvert, Storm Drain, and Sewer Pipe in December. The standard is the result of the most extensive research study to date on fibrous mixes for product meeting C13's benchmark, ASTM C76 Standard Specification for Reinforced Con- crete Culvert, Storm Drain, and Sewer Pipe. Overseeing the five-year study was Dr. Abol- maali, whose structural mechanics insights have landed him leading roles in National Transportation Safety Board investiga- tions—most notably those probing the 2007 Interstate 35W bridge collapse in Minneap- olis (steel plate fatigue) and 2006 failure of Boston Central Artery/Tunnel suspended precast ceiling anchors (epoxy creep). With ACPA and BASF assistance, he and fellow researchers tested pipe specimens a) 15- to 48-in. in diameter and of ASTM C76 Class I-V strength levels; b) fabricated on packerhead or vibration and compaction machinery; and, c) designed with conven- tional steel cage reinforcement or BASF's MasterFiber MAC Matrix synthetic macrofiber dosed at 6 to 18 lbs./cubic yard. Association member producers Forterra Building Products and Northern Concrete Pipe, respectively, supplied the small and medium bore pipe from Texas and Michigan plants for short- to long-term D-Load testing under lab or in-ground conditions. Dr. Abolmaali and the team were especially mindful of the creep performance of macrofiber specimens under long-term, sustained loading. Low rates of deformation over a period of 10,000 hours demonstrated how fibrous concrete pipe can perform to levels consistent with pub- lic agency and private construction owner expectations for drainage systems. BASF approached ACPA on dry cast pipe research after observing performance of the 2.1-in. polypropylene MasterFiber MAC Matrix as secondary reinforcement in slabs on grade, composite metal deck slabs, shotcrete, under- ground construction, septic tanks, vaults and other precast concrete elements. Results from testing at the UT-Arlington lab, plus Forterra and Northern Concrete plants, drove devel- opment of ASTM C1818. The standard estab- lishes a serviceability factor of 0.90 or higher for synthetic macrofibers specified in lieu of traditional steel reinforcement. That thresh- old reflects fibers' capacity to help fiber-re- inforced concrete pipes maintain at least 90 percent of their initial vertical internal diam- eter through 10,000 hours of loading—a mea- sure of reinforcing capacity, toughness and low creep performance. MasterFiber MAC Matrix is the first macro- fiber to meet ASTM C1818. In addition to sup- porting research underpinning the standard, BASF has created an analysis tool to calculate MasterFiber MAC Matrix economy against the use of conventional steel reinforcement. The calculator factors material, cage machinery and maintenance, plus cage fabrication and handling costs. "Fibers like MasterFiber MAC Matrix allow the concrete pipe to be lighter, safer, and eas- ier to install than concrete pipe made with traditional steel reinforcement," says BASF Industry Manager Kenneth Kruse. "The use of fibers can also improve long-term durability, and provide operational benefits to a produc- er when compared to casting pipe using tra- ditional steel cages. In turn, this makes con- crete pipe more competitive with product made from plastic and other materials." BASF mills first fiber to pipe standard recognizing synthetic alternatives to steel Three-edge bearing test determines fber-reinforced specimen's supporting strength, D-Load, and corresponding ASTM C76-defned Class. Transducers measure vertical and horizontal defections of pipe under loading. PHOTOS: BASF Admixture Systems

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