高强混凝土负温下强度发展的研究

混凝土受冻临界强度和负温强度发展是冬季施工主要参数，因此研究了掺与未掺防冻剂的C60混凝土在标准养护及-15℃条件下强度发展规律，测试了在标准养护下混凝土的28d抗压强度（f28），并研究了具有一定初始强度的C60高强混凝土置于-15℃条件7d再转入标准养护28d的抗压强度（f-7 28),通过对C60高强混凝土f-7 28与f28的比值，确定了掺防冻剂C60高强混凝土的抗冻临界强度，研究结果表明：掺防冻剂的C60高强混凝土在标准养护及-15℃条件下的抗压强度增长率均比未掺防冻剂C60高强混凝土的大，掺防冻剂的C60高强混凝土达到16.4MPa的抗冻临界强度后，负温冻结对其抗压强度的损伤很小，该混凝土可以进行冬季施工。

Development of strength in high strength conerete at minus- temperature

Frose-resisting critical strength and strength development at minus-temperature of concrete in winter are very important parameters.The strength of C60 grade of high strength concrete (HSC) with or without the antifreezing admixture is investigated under standard curing conditions and at 15 degree below zero. And the compressive strength of concrete on 28th day ( f 28 ) is measured under standard curing conditions. The strength of the HSC ( f -7+28 ) with some initial strength is researched under Standard 28 day curing conditians after being cured at 15 degree below zero for 7 days. The frost-resisting critical strength of HSC of C60 is decided at the ratio of f -7+28 to f +28 of HSC. Research results show: the increasing ratio of compressive strength of HSC with the antifreezing admixture is larger than the HSC without antifreezing admixture under standard curing conditions at 15 degree below zero. The HSC of C60 with antifreezing admixture is up to the critical strength of 16.4MPa.The effect of minus-temperature frost on compressive strength is very small. The HSC may be used for concreting construction in winter.