早龄期低钙粉煤灰基地聚物混凝土拉伸徐变特性

Tensile creep characteristics of early-age low-calcium fly ash-based geopolymer concrete

对早龄期低钙粉煤灰基地聚物混凝土拉伸徐变特性的把握,能够为受拉状态地聚物混凝土的应力解析及开裂预测提供重要的参数依据。采用自制混凝土拉伸徐变试验装置,通过恒定应力下的混凝土拉伸徐变试验获取混凝土比徐变、徐变增长速率等徐变特性,研究不同初始加载龄期(2、3、4 d)对低钙粉煤灰基地聚物混凝土拉伸徐变的影响。结果表明:高温密封养护可以使低钙粉煤灰基地聚物混凝土短时间内达到强度稳定状态;低钙粉煤灰基地聚物混凝土的拉伸徐变特性与普通水泥混凝土相似,试验初期阶段徐变增长速率较快,随持荷时间的增加,徐变增长速率迅速下降;在同一应力强度比下,初始加载龄期越大,比徐变越小,试验初期阶段的徐变增长速率也越小;相较于试验中期阶段与后期阶段,初始加载龄期对试验初期阶段的徐变影响更大。

Understanding of the tensile creep behavior of early-age low-calcium fly ash-based geopolymer concrete can provide reference for stress analysis and crack prediction of tensile concrete.A self-design testing set-up was used to obtain the creep behaviors of concrete such as the creep and creep growth rate under the constant tensile stress.The effects of different initial loading ages(2d,3d and 4d)on the behavior of tensile creep of early-age low-calcium fly ash-based geopolymer concrete were investigated.The results show that the condition of high temperature sealing curing can make the low-calcium fly ash-based geopolymer concrete reach the strength stability in a short time.The creep characteristics of the low-calcium fly ash-based geopolymer concrete are similar to those of the ordinary cement concrete.The initial creep growth rate is faster,and it decreases rapidly with time.Under the same stress-strength ratio of applied load,the larger the initial loading ages,the smaller the specific creep,and the smaller the creep growth rate at the initial stage of loading.The initial loading age has greater effect on the initial stage of loading compared with the mid and final stages.