Precast ‘crushable’ concrete equal to security applications

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“Crushable” concrete for better protection against terrorists … improved designs for precast rockfall barriers … corrosion of precast concrete barrier connections … lightweight, high-performance, self-consolidating concrete for bulb-T beams. They’re all part of new research presented earlier this year during the 94th annual Transportation Research Board annual meeting, which drew 12,000-plus design, engineering and allied professionals to Washington, D.C.

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Replacement of recycled concrete aggregate (RCA) for natural coarse aggregate by up to 45 percent by volume had no significant effects on any of the concrete properties studied, indicating high-quality RCA can be used as a replacement for a portion of the coarse natural aggregates in new portland cement concrete pavements. That’s what Haifang Wen, Ph.D., P.E., Washington State University; David I. McLean, Ph.D., P.E., Colorado State University; and, Kim Willoughby, Washington State DOT, report in their 2015 TRB paper, Evaluation of Recycled Concrete as Aggregates in New Concrete Pavements.

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A refined self-consolidating concrete (SCC) mix was developed to achieve the high workability needed for faster concrete discharge and finish, and attain the Florida Department of Transportation six-hour strength requirement of 2,200 psi (15 MPa) for concrete slab replacements, report Jamshid Armaghani, Ph.D., P.E., Global Sustainable Solutions, Gainesville, Fla.; Kamal Tawfiq, Ph.D., P.E., and Steven Squillacote, FAMU-FSU College of Engineering, Tallahassee; and, Michael Bergin, P.E., State Materials Office, Florida DOT-Gainesville, in their 2015 TRB paper, Accelerating Slab Replacement Using Self-Consolidating Concrete.

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Research in Mississippi shows that portland cement/limestone blends (PLC) result in notable compressive strength improvements in mixtures with high Class C fly ash replacement versus conventional Type I portland cement, say Jay Shannon and Dr. Isaac L. Howard, P.E., Mississippi State University, and V. Tim Cost, P.E., F.ACI, and Wayne M. Wilson, P.E., Holcim (US) Inc., in their 2015 TRB paper, Benefits of Portland-Limestone Cement for Concrete with Rounded Gravel Aggregates and Higher Fly Ash Replacement Rates.

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RCC proves ‘A-OK’ for Rebuilding Rural Roads

<table width="300" border="0" align="right" cellpadding="5"> <tr> <td>&nbsp;</td> </tr> <tr> <td>RCC is placed in Fayetteville Shale Play Area to accommodate heavy truck traffic resulting from the natural gas extraction boom. Different thicknesses and sub-bases were specified for comparison along the two-mile demonstration.

By Tom Kuennen

Roller-compacted concrete (RCC), followed by diamond grinding to smooth the surface, is the smart choice for rebuilding rural roads damaged by energy development truck traffic in Arkansas, according to new research presented at the 93rd annual meeting of the Transportation Research Board earlier this year in Washington, D.C.

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FRP Hybrids Make Encore Appearance at TRB 2014

PHOTOS: Aghahassani, Elbadry and Moravvej

After a strong showing in January 2013, glass and polymer fiber-reinforced polymer hybrid precast girders again dominated the technical presentations on precast technology and accelerated bridge construction at the 93rd annual meeting of the Transportation Research Board earlier this year in Washington, D.C.

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