苏联建筑法规СНиПⅢ-15-76(现浇混凝土及钢筋混凝土结构施工及验收规范)规定,无外加剂混凝土受冻前的临界强度,根据标号不同,应为7.5～15MPa。对于达到这个强度,规范建议在温度15～20℃条件下硅酸盐水泥混凝土的养护时间为1.5～7d。但 The Soviet Building Code СНиПIII-15-76 (Code for the Construction and Acceptance of Cast-in-Place Concrete and Reinforced Concrete Structures) states that the critical strength of concrete without admixture prior to freezing should be 7.5 to 15 MPa depending on the label. For achieving this strength, the specification suggests that the curing time of Portland cement concrete at a temperature of 15 to 20°C is 1.5 to 7 days. but