不同骨料水泥砂浆混凝土的干缩变形对比研究

Dry shrinkage deformation of cement mortar and concrete containing different aggregate

近年来,混凝土及材料界逐渐意识到,骨料特性不同,混凝土收缩行为有较大差别。针对水电工程常用的4种人工骨料,开展了水泥净浆、砂浆及混凝土的干缩变形试验。结果表明:其他条件一定时,不同品种骨料的砂浆与混凝土试件干缩率大小顺序为:砂岩最大,玄武岩和花岗岩次之,且两者相近,灰岩最小。另外,在相同干燥条件下,混凝土与砂浆的干缩均有良好的线性关系,骨料品种仅影响拟合公式的系数。而且不同品种混凝土的收缩行为是骨料原岩形成过程、孔隙结构、长期吸水性以及颗粒特性等多种因素影响的结果。工程选择骨料料源时,应针对不同品种骨料对混凝土收缩行为的影响,开展大坝裂缝的提前预防。

It is noted that great difference of concrete shrinkage arises from application of various aggregate. Dry shrinkage tests for cement paste, mortar and concrete were carried out using four popular artificial aggregates. When other condition is fixed, the downward dry shrinkage order of mortar and concrete containing different aggregate is as follow： sandstone 〉 basalt ≈granite 〉 limestone. Under the same moisture condition, a fine linear relation can be found between mortar shrinkage and concrete shrinkage, and the aggregate type can only exert influence on coefficient of the fitting formula. Moreover, the shrinkage behavior of concrete containing different aggregates is influenced by various factors such as original lithology of aggregate, pore structure, long - term water absorption and particle characteristics. In aggregate selection in engineering, concrete crack prevention measures should be proposed according to the different concrete shrinkage features that are influenced by different aggregates.