组合养护参数优化对超高性能混凝土力学性能及高温爆裂的影响

发布时间：2019-05-23 18:23

【摘要】：本论文主要研究了养护制度对含粗骨料超高性能混凝土(Ultra-high Performance Concrete with Coarse Aggregate,UHPC(CA))力学性能和高温爆裂的影响,研究变量包括养护方式、热水养护温度和时长、干热养护温度和时长、钢纤维。本研究首先通过实验确定了对提高UHPC强度和抗爆裂性能最有利的组合养护方式。在此基准上改变干热养护温度水平,研究了干热养护温度对UHPC强度和抗爆裂性能的影响。最后研究了组合养护对UHPC(CA)抗压强度、劈裂抗拉强度、断裂能及高温爆裂的影响。常温力学性能试验结果显示:(1)在不同热水养护温度下,热水养护最佳时长有所不同。当热水养护温度为60℃和90℃时,热水养护最佳养护时长分别为4 d和3d。(2)与标准养护相比,组合养护过后,UHPC的抗压强度和劈裂抗拉强度均有大幅增加。对于素UHPC来说,组合养护后混凝土的断裂能均大于标准养护后,但对于掺钢纤维的UHPC来说,组合养护对混凝土的断裂能带来了不利影响。高温爆裂试验结果显示:标准养护下的UHPC在高温爆裂试验中均发生非常严重的爆裂。组合养护可以显著提高UHPC的高温爆裂性能,且提高效果与热水养护和干热养护的温度和时长密切相关,随着热水养护时长增加,UHPC高温性能越差;提高干热养护温度能在UHPC中达到消除爆裂的效果。高温后残余力学强度试验结果显示:组合养护条件下,UHPC经过高温爆裂试验后仍然具有较高的残余抗压强度和残余劈裂抗拉强度。同时,掺加钢纤维有利于提高UHPC高温后的残余强度;且与单掺钢纤维相比,两种钢纤维混掺时效果更佳。本文研究表明,组合养护的方法可以大幅提高其基本力学性能和抗爆裂性能。热水养护及干热养护的温度、时长均会对UHPC强度产生一定影响。标准养护条件下,钢纤维能对UHPC的高温爆裂起到一定缓解。组合养护条件下,UHPC经过高温爆裂试验后仍然具有较高的残余强度。
[Abstract]:In this paper, the effect of curing system on the mechanical properties and high temperature burst of ultra-high performance concrete (Ultra-high Performance Concrete with Coarse Aggregate,UHPC (CA) containing coarse aggregate is studied. The variables include curing mode, hot water curing temperature and time. Dry heat curing temperature and time, steel fiber. In this study, the most favorable combination maintenance method for improving the strength and burst resistance of UHPC was determined by experiments. The effect of dry heat curing temperature on the strength and burst resistance of UHPC was studied by changing the level of dry heat curing temperature. Finally, the effects of combined curing on the compressive strength, split tensile strength, fracture energy and high temperature burst of UHPC (CA) were studied. The results of mechanical properties test at room temperature show that: (1) the optimum time length of hot water curing is different at different hot water curing temperatures. When the curing temperature of hot water is 60 鈩，

本文编号：2484117