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为研究现浇混凝土在低温暴露条件下养护时的早期强度增长规律，试验设置5℃、0℃、-5℃三个低温环境，凝结期以贯入阻力为指标，硬化期以抗压强度为指标，研究了混凝土从浇注到90 d不同龄期的强度变化规律；结果表明：完全暴露在负温环境下不做任何养护的混凝土并未停止凝结硬化；负温暴露养护会严重延长C30混凝土的初凝时间，约为0℃时的5倍，对C50混凝土影响不大；负温暴露养护下C30混凝土硬化后的强度明显偏低，90 d强度仍达不到设计强度，对C50混凝土影响不大；负温暴露养护下，混凝土的终凝时间及强度增长速度与海拔和当地最冷月平均温度呈正相关关系，C30混凝土在低温暴露养护下的28 d比3d抗压强度增幅较大，比值达6.17,C50混凝土强度发展较稳定比值最大1.86;建议久马高速在建设过程中从10月至次年4月浇注混凝土后即刻对C30等低标号混凝土构件与大地连接部位进行密封热养护，避免低标号混凝土凝结前在负温下暴露，对于C50混凝土若不得已暴露在低温环境，需延长拆模时间。
Abstract：To study the early strength growth law of cast-in-place concrete during curing under low temperature exposure conditions, three low temperatures of 5 ℃, 0 ℃, and-5 ℃ were set up in the experiment. The setting period was based on penetration resistance, and the hardening period was based on compressive strength. The strength change law of concrete at different ages from pouring to 90 days was studied; The result indicate that concrete completely exposed to negative temperature without any curing has not stopped setting and hardening; Negative temperature exposure curing can significantly prolong the initial setting time of C30 concrete, about 5 times than that at 0 ℃, but has little effect on C50 concrete. The strength of C30 concrete after hardening under negative temperature exposure curing is significantly lower, and the 90 d strength still cannot reach the design strength, which has little impact on C50 concrete; Under negative temperature exposure curing, the final setting time and strength growth rate of concrete are positively correlated with altitude and the average temperature of the coldest month in the local area. The compressive strength of C30 concrete fluctuates greatly between 28 days and 3 days under low temperature exposure curing, with a ratio of 6.17. The strength development of C50 concrete is relatively stable. It is recommended that during the construction process of Jiu-ma Expressway, special efforts should be made to strengthen the sealing, heating, and curing of low concrete grade components such as C30 at the connection with the ground from October to April of the following year. The concrete with low grade should be avoided curing in minus temperature. The C50 concrete need prolong the curing time before the template removal.
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基本信息:
DOI：10.13928/j.cnki.wrahe.2024.S2.110
中图分类号:U445.57
引用信息:
[1]方仁义,于蕾,范波,等.低温暴露养护条件下混凝土强度增长规律研究[J].水利水电技术(中英文),2024,55(S2):733-739.DOI:10.13928/j.cnki.wrahe.2024.S2.110.
基金信息:
四川省交通运输科技计划项目(2019-ZL-18)