制备工艺对再生骨料混凝土性能的影响

考虑水灰比为0.50、0.25及用量只有最前者一半的水泥净浆浸泡再生粗骨料混凝土制备工艺、普通工艺和两阶段制备工艺,测定了由其拌制的再生混凝土的性能。结果发现,水灰比为0.50的全部水泥净浆浸泡再生骨料制备工艺,可提高再生混凝土28 d的抗压强度,但效果并不显著;56 d抗压强度反而有所降低,这两种龄期的劈拉强度均较低,且抗压强度离散性大;水灰比为0.25的全部水泥净浆浸泡再生骨料制备工艺,抗压、拉强度均最低,抗压、拉强度离散性大。用量一半的水泥净浆浸泡再生骨料工艺,有较高的抗压、拉强度,且强度离散性较小,但不及普通工艺和两阶段制备工艺。两阶段制备工艺不但能提高再生混凝土的抗压强度、劈拉强度,还能改善其工作性能,且强度离散性小,是制备再生混凝土的一种最优工艺。由普通工艺制备的再生混凝土,抗压、抗拉强度值均较高,强度离散性也较小,且工艺简单,也是一种较好的制备工艺。

EFFECT OF MIXING PROCESS ON THE PERFORMANCE OF RECYCLED AGGREGATE CONCRETE

Five mixing processes of producing recycled concrete were considered,including cement paste soaking recycled coarse aggregate process,whose water-cement ratio is 0.50,025,and cement paste dosage is only half.The other two processes are traditional process and two-stage mixing process.The performance of recycled concrete produced by them was measured.It was found that the first mixing process could indistinctively improve 28 d compressive strength of recycled concrete,instead of the strength of 56 d reduced,the splitting tensile strength of the two ages were both relatively low,moreover,the discreteness of compressive strength was big;the compressive and tensile strengths of recycled concrete produced by the second mixing process were the lowest,moreover,the discreteness of strength was big;the both of strength produced by the third mixing process was higher than that of the former two,but the discreteness of strength was less than that of the former two,but bigger than that of the latter two.The two-stage mixing process could not only improve the compressive strength and splitting tensile strength of recycled concrete but also improve its working performance.Meanwhile,the discreteness of the strength of concrete made by this way is small.The recycled concrete produced by the traditional process also shows high compressive strength,high tensile strength and low discreteness of strength and this process is quite simple.