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原文传递 DEVELOPMENT OF OPTIMAL CONCRETE MIX DESIGNS FOR BRIDGE DECKS.

题名：	DEVELOPMENT OF OPTIMAL CONCRETE MIX DESIGNS FOR BRIDGE DECKS.
作者：	Xi-Y; Shing-B; Xie-Z
关键词：	Bridge-decks; Cement-content; Chlorides-; Coarse-aggregates; Compressive-strength; Cracking-; Durability-; Fly-ash; High-performance-concrete; Mix-design; Overlays-Pavements; Permeability-; Silica-fume; Summer-; Water-cement-ratio; Winter-
摘要：	As part of a national experiment sponsored by the Federal Highway Administration under the Innovative Bridge Research and Construction (IBRC) program, the Colorado Department of Transportation (CDOT) developed High Performance Concrete (HPC) mixes for bridge decks. The ultimate goal of these experimental HPC mixes was to improve durability by reducing shrinkage cracking, thermal cracking and permeability while maintaining current standards for workability and strength. The results of this study revealed that (1) the ratio of water to cementitious materials has the most significant effect on chloride permeability; (2) permeability is not strongly correlated to the total air entrainment; (3) the time for the first cracking to occur is directly related to the cement content and thus the strength of concrete; (4) Class F fly ash is better than Class C fly ash in improving both the chloride permeability and cracking resistance of concrete; (5) a proper increase of coarse aggregate can improve permeability, cracking, and the 28-day strength of concrete. Three different mixes were developed; two for the summer and winter seasons, and one mix design with a different gradation for thin overlays. The results of this study showed that by adding 4% silica fume and reducing cement content from over 600 lb/cu yd to below 500 lb/cu yd, the 56-day permeability could be reduced from 6000 Coulomb to 2000 Coulomb which maintaining workability and strength. The use of the newly developed concrete mix designs (two for bridge decks and one for thin overlay) is recommended. On an experimental basis, CDOT has used these mixes on an urban interchange at I-225 and Parker Road.
总页数：	2001/06. pp60 (Phots., Figs., Tabs., 47 Ref., 3 App.)
报告类型：	科技报告