长期荷载作用下再生混凝土梁裂缝宽度试验研究

Experimental study on crack width of recycled aggregate concrete beam under long-term loading

对再生混凝土梁长期荷载作用下裂缝宽度变化进行试验研究,重点分析不同再生粗骨料取代率时再生混凝土梁裂缝随时间变化而发展的规律。研究结果表明:长期加载过程中,随着取代率增加再生混凝土梁主裂缝旁的次生裂缝与新生裂缝变多且分布不均,同时再生混凝土较普通混凝土梁裂缝宽度增长时期出现显著"后延"特点,且增长期持续时间变长。通过对裂缝宽度附加时变系数分析,提出不同取代率情况下长期扩大系数,采用系数法建立适于长期荷载作用下的再生混凝土梁最大裂缝宽度计算公式。

Crack width of recycled concrete beams were investigated experimentally under long-term loading. The variation of crack width with time for recycled concrete at different replacement rates was analyzed and compared. Results show that under long-term loading, the cracking pattern of recycled concrete beam with high replacement rate is more complicated and random than that of recycled concrete beam with low replacement rate. The branching and converging of cracks is more likely to occur in recycled concrete beam with high replacement rate than in that with low replacement rate. The rapid growth period of crack width in recycled aggregate concrete beam is obviously prolongated and increasedcompared to normal concrete beam. By analyzing additional time-varying coefficient of crack width, the long-term enlargement coefficient for different replacement rates is proposed, and calculation formula of maximum crack width suitable for recycled aggregate concrete beam under long-term loading is established.