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原文传递 Evaluation of the Performance of Concretes Containing Fly Ash and Ground Slag in Bridge Decks.

题名：	Evaluation of the Performance of Concretes Containing Fly Ash and Ground Slag in Bridge Decks.
作者：	lane, d. s.
关键词：	petrographic analysis, drill core analysis, virginia, concrete durability
摘要：	Cores from 36 bridge decks were evaluated to assess the condition and quality of the concrete by petrographic methods and direct and indirect measures of the transport properties. Transport properties were measured by a rate of absorption test (ASTM C 1585) and by electrical conductance using the rapid chloride permeability apparatus (ASTM C 1202). The decks were distributed across Virginia to reflect the varied geographic and climatic regions. Two bridge age groups, each constructed under different specifications, were represented: (1) from 1968 through1971, where portland cement concrete with a maximum specified watercementitious material ratio (W/C) of 0.47 was used with uncoated reinforcing steel; and (2) from 1984 through1991, where the specification required a maximum W/CM of 0.45, required epoxy-coated reinforcement, and allowed the use of fly ash or ground slag as supplementary cementitious materials. The older group included 10 decks, and the younger included 26. In the younger group, 8 were identified as containing fly ash and 7 were identified as containing slag. Five of the concretes exhibited excessively high spacing factors, suggesting susceptibility to freezing and thawing damage, although only two showed signs of such damage. Four of the decks exhibited excessively small spacing factors that could significantly affect strength. Signs of poor paste quality attributable to excessive water were noted in approximately one third of the concretes. Cracking was of significance in 12 decks but was limited to paste cracking in 6; of these, 5 contained either fly ash or slag. Four showed signs of damage related to alkali-aggregate reactions, including 3 with carbonate rocks, 1 of which contained slag. A general assessment based on petrographic observations showed a fairly even distribution of good, fair, and poor ratings. / NOTE:Final research rept. May 99-Aug 06.
总页数：	u0702；23p
报告类型：	科技报告