热养护过程中超高性能混凝土的收缩性能研究∗

摘要

Heat curing can improve the strength of UHPC and reduce the dry shrinkage of UHPC.Thus,the way of curing is widely applied in engineering practice.The shrinkage performance of UHPC during heat curing and the microstructure of UHPC under the different age of heat curing were studied.The experiment results showed that the shrinkage of UHPC could not be observed obviously until the curing temperature reached to 50 ℃ during heat cu-ring.While the curing temperature was close to 70 ℃,the value of shrinkage increased rapidly and reached to 450 × 10 -6 ultimately.With the increasement of reinforcement ratio,the shrinkage of UHPC reduced during heat curing.The matrix of UHPC became dense,the content of Ca(OH)2 decreased greatly and the degree of hydration increased greatly after heat curing.%热养护能够提高 UHPC 的强度和减小 UHPC 的干燥收缩,已经广泛应用于工程实践中。主要研究了UHPC 在热养护过程中的收缩变形性能和不同热养护龄期下 UHPC 的微观结构。结果表明,在热养护过程中,UH-PC 在50℃以内基本不发生收缩,当温度接近70℃时,收缩值迅速增加,最终的收缩值为450×10-6；随着配筋率的提高,UHPC 在热养护过程中的收缩减小。热养护后,基体变得致密,Ca(OH)2的含量大幅减少,水化程度大大提高。