硫酸盐作用下轻骨料混凝土受压细观裂纹扩展及演变规律

发布时间：2019-06-12 12:24

【摘要】：为了给轻骨料混凝土在桥梁中的拓展应用提供理论基础,利用一级粉煤灰等体积取代30%普通砂,硅灰等质量取代10%水泥,并用破碎型和圆球型页岩陶粒制备了2种轻骨料混凝土。通过强度试验、工业CT试验、硫酸盐溶液干湿循环等试验,对抗蚀性、断面CT数、裂纹演变规律、裂纹增速影响因子进行了研究,分析了轻骨料混凝土在硫酸盐腐蚀作用下,细观裂纹扩展及动态演变规律。结果表明:在质量分数为5%的Na2SO4溶液作用下,干湿循环50次后,破碎型和圆球型页岩陶粒轻骨料混凝土抗蚀系数分别为普通混凝土的1.12倍和1.17倍,且其破坏面主要表现为贯穿骨料破坏;试样从微裂纹产生到整体破坏大体可分为压密、裂纹萌生发展、裂纹扩展贯通和破坏4个阶段;随着干湿循环次数的增加,轻骨料混凝土裂纹增速影响因子和弹性模量损失均小于普通混凝土,且破碎型轻骨料混凝土略大于圆球型轻骨料混凝土。
[Abstract]:In order to provide a theoretical basis for the expansion and application of lightweight aggregate concrete in bridges, two kinds of lightweight aggregate concrete were prepared by replacing 30% ordinary sand with primary fly ash and 10% cement by mass of silica fume, and two kinds of lightweight aggregate concrete were prepared with broken and spherical shale ceramsite. The corrosion resistance, cross section CT number, crack evolution law and crack growth influencing factors of lightweight aggregate concrete under sulfate corrosion were studied by strength test, industrial CT test and dry and wet cycle test of sulfate solution. The microcrack propagation and dynamic evolution of lightweight aggregate concrete under sulfate corrosion were analyzed. The results show that under the action of 5% Na2SO4 solution, the corrosion resistance coefficients of broken and spherical shale ceramsite lightweight aggregate concrete are 1.12 times and 1.17 times of those of ordinary concrete, respectively, and the failure surface is mainly penetrating aggregate failure, and the specimen can be divided into four stages: compaction, crack initiation and development, crack propagation and failure, and the failure surface of the specimen can be divided into four stages: compaction, crack initiation and development, crack propagation and failure, and the corrosion resistance of broken shale ceramsite lightweight aggregate concrete is 1.12 times and 1.17 times higher than that of ordinary concrete, and the failure surface of the specimen can be divided into four stages: compaction, crack initiation, crack propagation and failure. With the increase of dry and wet cycle times, the influence factors of crack growth and elastic modulus loss of lightweight aggregate concrete are smaller than those of ordinary concrete, and the broken lightweight aggregate concrete is slightly larger than that of spherical lightweight aggregate concrete.
【作者单位】：长沙理工大学交通运输工程学院;
【基金】：国家自然科学基金项目(11072041) 湖南省自然科学基金项目(13JJ3070)
【分类号】：U444;U445.57

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