摘   要：为研究低温、大温差地区预制混凝土箱梁在蒸汽养护条件下温度及强度变化规律，测试了低温、大温差地区不同养护方式（标准养护、蒸汽养护、自然养护）条件下，混凝土试验箱梁温度及各龄期（3 d、5 d、7 d、14 d、28 d、56 d）的强度，试验结果表明：低温、大温差地区自然养护条件下，预制混凝土箱梁温度在浇筑后的28 h时达到峰值，在45 h时降到入模温度，龄期7 d时温度降到最低；蒸汽养护恒温65 ℃较恒温45 ℃早期强度增长快，而后期56 d龄期时强度小于恒温45  ℃。同时，蒸汽养护恒温45 ℃升温过程比恒温65 ℃升温过程稳定、易控制；56 d混凝土抗压强度比较，由大到小依次为标准养护＞蒸汽养护（45 ℃）＞蒸汽养护（65 ℃）＞自然养护。

Abstract: In order to study the hydration reaction regularity and strength change of precast concrete box girder at low temperature and large temperature difference area, the temperature of concrete of box girder under different curing methods (standard curing, steam curing, natural curing) at low temperature and large temperature difference areas and the strength of each age (3 d, 5 d, 7 d, 14 d, 28 d, 56 d) were tested. The results show that the temperatures of concrete box girders under natural curing in low temperature and large temperature difference area reach the peak value at 28 h after pouring, and fall to the entering mould temperature at 45 h, then maintain a slow hydration reaction at 3~5 d, and drop to the lowest at 7 d , and the hydration reactions basically ended. Strength of steam curing at 65 ℃ increases faster than that at 45 ℃ in the early stage, but it′s lower than that at 45 ℃ in the later stage of 56 d. And the heating process of steam curing at 45 ℃ is more stable and easy to control than that of 65 ℃. According to the compressive strength of concrete at the age of 56 d, the strength is of the decreasing order among is standard curing, steam curing at 45 ℃ and steam curing at 65 ℃ and natural curing.