Optimization of steam-curing regime for high-strength, self-consolidating concrete for precast, prestressed concrete applications

摘要

>Steam curing is often used in precast concrete manufacturing plants to accelerate strength gains. The mechanical properties of steam-cured concrete are affected by mixture composition and can vary widely with steam-curing parameters. The main objective of the study reported in this paper is to optimize the steam-curing regime of high-strength self-consolidating concrete (SCC). Test parameters included the preset period, the maximum chamber temperature, and the rate of heating. Two SCC mixtures were optimized to secure design compressive strengths of 8700 and 11,600 psi (60 and 80 MPa). The mixtures were prepared with a water-cementitious materials ratio of 0.38 and 0.28, respectively. The maximum chamber temperature was shown to have a dominant effect on the 18-hour compressive strength. The preset period also exhibited significant influence on compressive strength and elastic modulus. For a given maximum chamber temperature of 140?°F (60?°C), an increase in preset period from 2 to 5 hours resulted in a 5% increase in early-age strength.>References style="text-align: left;">1. ACI (American Concrete Institute) Committee 237. 2007. Self-Consolidating Concrete. ACI 237R-07. Farmington Hills, MI: ACI. style="text-align: left;">2. CSA (Canadian Standards Association). 2005. Precast Concrete - Materials and Construction. CSA A23.4. Rexburg, ON, Canada: CSA. style="text-align: left;">3. PCI Interim SCC Guidelines Fast Team. 2003. Interim Guidelines for the Use of Self-Consolidating Concrete in Precast/Prestressed Concrete Institute Member Plants. 1st ed. Chicago, IL: PCI. style="text-align: left;">4. PCA (Portland Cement Association). 2006. Design and Control of Concrete Mixtures. Skokie, IL: PCA. style="text-align: left;">5. ACI Committee 517. 1992. Accelerated Curing of Concrete at Atmospheric Pressure. ACI 517.2R-87,  revised 1992. Farmington Hills, MI: ACI. style="text-align: left;">6. AASHTO (American Association of State Highway and Transportation Officials). 2004. AASHTO LRFD  Bridge Design Specifications. 3rd ed. Washington, DC: AASHTO. style="text-align: left;">7. TxDOT (Texas Department of Transportation). 2004. Standard Specifications for Construction and Maintenance  of Highways, Streets, and Bridges. Texas:TxDOT. style="text-align: left;">8. FDOT (Florida Department of Transportation). 2004. Standard Specifications for Road and Bridge Construction.  Tallahassee, FL: FDOT. style="text-align: left;">9. NYSDOT (New York State Department of Transportation). 2002. Standard Specifications - Construction  and Materials. Albany, NY: NYSDOT. style="text-align: left;">10. Washington Department of Transportation. 2002. Standard Specifications. M 41-10 2008. Olympia, WA:  Engineering Publications. style="text-align: left;">11. Korea Concrete Institute. 2003. Standard Specifications  for Concrete. Seoul, Korea: Korea Concrete Institute. style="text-align: left;">12. Odler, I., and Y. Chen. 1995. target="_blank" title="a€?Effect of Cement Composition on the Expansion of Heat-Cured Cement Pastes.a€?" href=" http://dx.doi.org/10.1016/0008-8846(95)00076-o ">a€?Effect of Cement Composition on the Expansion of Heat-Cured Cement Pastes.a€? Cement and Concrete Research 25 (4): 853-862. style="text-align: left;">13. Tepponen, P., and B.-E. Eriksson. 1987. a€?Damages in Concrete Railway Sleepers in Finland.a€? Nordic Concrete Research 6: 199-205. style="text-align: left;">14. Klieger, P. 1960. a€?Some Aspects of Durability and Volume Change of Concrete for Prestressing.a€? Research Department Bulletin 118. Journal of the PCA  Research and Development Laboratories 2 (3): 2-12. style="text-align: left;">15. Siedel, H., S. Hempel, and R. Hempel. 1993. target="_blank" title="a€?Secondary Ettringite Formation in Heat Treated Portland Cement Concrete: Influence of Different w/c Ratios and He