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再生骨料具有较高的吸水率,进行配合比设计时必须考虑其吸水性。按一系列净水胶比(W0/B),基于吸水率制备再生混凝土试样,以研究配合比与骨料级配对再生混凝土砖强度的影响。试验结果表明,当再生骨料最大粒径16mm、净水胶比0.49时,再生混凝土砖28d强度达16.2MPa;当再生骨料最大粒径5mm、净水胶比0.40时,再生混凝土砖强度达22.8MPa。总体说来,净水胶比在0.55以下时,再生混凝土砖的强度均能达到MU10级以上。在再生混凝土砖中,再生骨料所吸的水起到自养护作用,既不增大净水胶比,又为胶凝材料水化提供了补充来源,对提高强度有利。当再生骨料最大粒径为5mm时,不必另外加砂。用废弃混凝土制备再生砖时,合理的最大粒径宜为16mm。
Recycled aggregate has a high water absorption, the ratio of design must take into account its water absorption. According to a series of W0 / B ratio, samples of recycled concrete were prepared based on water absorption to study the effect of mix ratio and aggregate gradation on strength of recycled concrete brick. The results show that the strength of recycled concrete brick reaches 16.2MPa when the maximum aggregate size of regenerated aggregate is 16mm and the ratio of purified water to binder is 0.49. When the maximum size of recycled aggregate is 5mm and the ratio of purified water to binder is 0.40, 22.8MPa. Overall, the strength of recycled concrete brick can reach above MU10 level when the water-purification glue ratio is below 0.55. In the recycled concrete brick, the water absorbed by the recycled aggregate plays a role of self-curing, which does not increase the water-cement ratio, but also provides a supplementary source for the hydration of the cementitious material, which is beneficial to increase the strength. When the maximum aggregate size of recycled aggregate is 5 mm, it is not necessary to add additional sand. Recycled brick with waste concrete preparation, the reasonable maximum size should be 16mm.