气冻气融作用下混凝土抗冻性及损伤层演化规律研究

发布时间：2018-01-05 07:25

本文关键词：气冻气融作用下混凝土抗冻性及损伤层演化规律研究　出处：《铁道学报》2017年03期 　论文类型：期刊论文

【摘要】：采用气冻气融的方式,分别对C30、C40、C50、C40(商品混凝土,简称商混)4组不同配比试块及1组C40(商混)的足尺(150mm×300mm×2 700mm)钢筋混凝土梁进行冻融耐久性试验。用超声波平测法测定不同冻融循环次数时的混凝土损伤层厚度,研究冻融对混凝土损伤层厚度的影响规律;通过与传统抗冻性评价指标劣化规律的对比分析,提出以冻融损伤层厚度为损伤变量的评价标准,结合实际损伤特点,对所提出损伤变量进行相应修正,并验证其合理性;建立混凝土冻融损伤层厚度的随机预测模型;通过案例分析,验证模型的适用性,讨论冻融环境下混凝土最小保护层厚度的问题。研究结果表明:随着冻融循环次数的增加,混凝土相对动弹性模量、抗压强度逐渐减小;试件质量略有增大;冻融损伤层厚度逐渐增大,即冻融损伤度逐渐增大,且强度越低,损伤度越大;冻融环境下混凝土结构的最小保护层厚度偏于不安全。
[Abstract]:In this paper, the method of air freezing and air melting is used to separate the C30 C 40 C 40 C 50 C 40 (commercial concrete). For short, the full scale of 150mm 脳 300mm 脳 2700mm of four groups of quotient mixture and 1 group of C40 (quotient blending). The durability test of reinforced concrete beams was carried out. The thickness of damage layer of concrete was measured by ultrasonic wave leveling method under different freeze-thaw cycles. The influence of freeze-thaw on the thickness of concrete damage layer is studied. By comparing and analyzing the deterioration law of traditional evaluation index of frost resistance, this paper puts forward the evaluation standard of frost thawing damage layer thickness as damage variable, combined with the actual damage characteristics, the damage variable is revised accordingly. And verify its rationality; A stochastic prediction model for the thickness of concrete freeze-thaw damage layer is established. Through case analysis, the applicability of the model is verified, and the problem of the minimum cover thickness of concrete in freeze-thaw environment is discussed. The results show that the relative dynamic elastic modulus of concrete increases with the increase of freeze-thaw cycles. The compressive strength decreases gradually; The quality of the specimen increased slightly; The thickness of freeze-thaw damage layer increases gradually, that is, the degree of freeze-thaw damage increases gradually, and the lower the intensity, the greater the damage degree. In freeze-thaw environment, the minimum cover thickness of concrete structure is less than that of safety.
【作者单位】：西安科技大学建筑与土木工程学院;西安建筑科技大学土木工程学院;
【基金】：国家自然科学基金(51278403) 教育部“创新团队发展计划”(IRT13089)
【分类号】：TU528
【正文快照】： 近年来,因混凝土材料耐久性劣化导致的工程结构问题越来越多,并造成了巨大的经济损失。在各类混凝土结构耐久性问题中冻融破坏是较为典型的一种[1-3]。目前,多采用相对动弹性模量、抗压强度、质量损失这三个指标对混凝土的抗冻性能进行评价与研究[4-6]。但对实际工程中的混凝

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