再生混凝土早龄期拉伸徐变试验研究

Experimental Study on Tensile Creep of Recycled Aggregate Concrete at Early Age

为掌握再生混凝土的抗裂性能,通过单轴拉伸徐变试验,研究了再生粗骨料取代率(质量分数)、矿物掺和料掺量(质量分数)对再生混凝土早龄期拉伸徐变性能的影响.结果表明:再生粗骨料取代率为50%~100%的再生混凝土拉伸徐变较普通混凝土增加8%~31%;再生混凝土拉伸徐变随矿物掺和料掺量的增加而增大,粉煤灰单掺和粉煤灰+矿渣复掺可使再生混凝土拉伸徐变分别增加8%~32%,3%~22%.以混凝土拉伸徐变M-Burgers预测模型为基础,考虑再生骨料取代率和矿物掺和料掺量的影响,提出了适用于再生混凝土早龄期拉伸徐变的预测模型.

To acquire crack resistance property of recycled aggregate concrete,effect of substitution percentage(by mass)of recycled coarse aggregate and addition amount of mineral admixture on tensile creep property of recycled aggregate concrete at early age was investigated by uniaxial tensile creep experiment.The test results show that compared with normal concrete,tensile creep of recycled aggregate concrete increases by 8%31%for recycled coarse aggregate with substitution percentage of 50%100%.Higher addition amount of mineral admixture will result in higher tensile creep in recycled aggregate concrete.The single addition of fly ash and mixed addition of fly ash with slag will increase tensile creep of recycled aggregate concrete by 8%32%and 3%22%respectively.Based on concrete tensile creep prediction M-Burgers model,a model suitable for tensile creep prediction of recycled aggregate concrete at early age is proposed by considering the influence of substitution percentage of recycled coarse aggregate and addition amount of mineral admixture.