渡槽高性能混凝土抗干缩试验研究

南水北调中线工程洺河渡槽采用高强高性能混凝土施工,针对渡槽簿壁结构、高强混凝土低水胶比等特点,结合工程实际,试验研究多种影响因素下混凝土抗干缩性能,分析探讨干缩变形变化规律。结果表明,渡槽簿壁结构高性能混凝土,可能产生较大的干缩变形,特别在早期易产生干缩变形及干缩裂缝。适宜的水胶比和适量的粉煤灰掺量,对于减小干缩变形以及可能产生的干缩裂缝是有作用的,特别在早期,抗干缩作用尤为显著。高性能混凝土干缩变形变化规律可用εt=ALn（t）-B表述。

Experimental Study on Drying Shrinkage Resistance of High Performance Concrete for Aqueduct

High strength and high performance concrete were used in Ming-river aqueduct in Middle Route of South-to-North Water Transfer Project. Based on the characteristics of the thin walled aqueduct and the low water-to-binder ratio of high strength concrete, as well as considering the practical project, this paper studied the properties of drying shrinkage resistance of concrete under the influence of various factors and explored the change regularity of drying shrinkage deformation. The results show that, for the high performance concrete used in thin welled aqueduct, large drying shrinkage may occur. It is worthwhile to note that this situation can easily take place in early-age and even leads to cracks.Proper water-to-binder ratio and moderate amount of fly-ash are favorable to reducing drying shrinkage and the probable cracks produced by it, and especially in early-age this benefit is prominent. The change law of drying shrinkage deformation for high performance concrete can be expressed by formula εt = A Ln(t)-B.