不同养护条件对混凝土长期收缩变形性能的影响

Effect of different curing conditions on long-term shrinkage deformation of concrete

研究了在不同养护条件下对不同强度等级混凝土长期收缩变形性能的影响,并将收缩变形测试结果与典型收缩模型的计算结果进行比较。研究表明,在前14 d密封养护随后进行干燥养护条件下,C60混凝土前14 d的自收缩最大,14 d后C60混凝土的干燥收缩变形明显较小,并且与直接干燥养护的混凝土相比,混凝土的总收缩变形显著增大。在先密封养护至自收缩稳定后进行干燥养护条件下,自收缩稳定后混凝土仍会产生较明显的收缩变形,但与直接干燥养护的混凝土相比,混凝土的总收缩变形显著减小。当采用EN1992、fib MC2010、ACI 209—2R和B4几种收缩模型计算时,fib MC2010模型的计算值与实测结果拟合程度最好,EN1992模型和B4模型其次,最后是ACI 209—2R模型。但几种模型计算值与实测结果的总体吻合度均较好,可用于预测混凝土的长期变形性能。

The effects of different curing conditions on the long-term shrinkage deformation of concrete with different strength grades were studied,and the test results of shrinkage deformation were compared with the calculation results of shrinkage models.The results show that,under the condition of sealing curing for the first 14 days followed by dry curing,the autogenetic volume deformation of C60 concrete is the largest in the first 14 days,and the drying shrinkage deformation of C60 concrete is obviously smaller after 14 days.Compared with the concrete cured by direct drying,the total shrinkage deformation of concrete increases significantly.Under the condition of sealing curing to self shrinkage stabilization and then drying curing,concrete will still produce obvious shrinkage deformation after self shrinkage stabilization,but the total shrinkage deformation of concrete is significantly reduced compared with the concrete cured by direct drying.When EN 1992,fib MC2010,ACI 209—2R and B4 shrinkage models are used to calculate,fib MC2010 model has the best fitting degree with the measured results,EN1992 model and B4 model is the second,ACI 209—2R model is the last.However,the calculated values of several models are in good agreement with the measured results,which can be used to predict the long-term deformation performance of concrete.