废旧橡胶粉混合骨料混凝土力学性能及耐久性的试验研究

发布时间：2018-11-07 11:43

【摘要】：本文以再生骨料和天然浮石为粗骨料,用再生骨料等体积取代浮石,从宏观和微观两个方面,研究再生骨料取代率分别为0%、30%、50%、70%、100%混合骨料混凝土的基本力学性能及耐久性能,从中筛选出最优的取代率。试验结果表明:随着再生骨料取代率的增大,混合骨料混凝土的立方体抗压强度逐渐在增大,其劈裂抗拉强度以取代率30%为界,呈现先升高后降低的趋势;从混凝土的质量损失、相对动弹性模量损失和外观剥落情况,发现再生骨料取代率为50%和70%的混合骨料混凝土表现出了良好的抗冻性;再生骨料取代率增大,混合骨料混凝土中的气孔含量减小;混凝土中孔结构的含量是影响混凝土抗压强度的主要因素之一。试验结果得出再生骨料取代率为50%为最优的取代率,用废旧轮胎橡胶粉混凝土做进一步的改性研究。废旧橡胶粉粒径分别为20目、60目、80目、100目、120目,按照胶凝材料3%、6%、9%掺量进行掺入,分析混合骨料混凝土早期的力学性能及微观结构。试验结果表明:在粒径相同的条件下,废旧橡胶粉使混合骨料混凝土的抗压强度降低率增大;从环境扫描电镜中得出,橡胶粉、再生骨料、浮石与水泥界面是薄弱区域,是造成混合骨料混凝土强度降低的主要原因。
[Abstract]:In this paper, regenerated aggregate and natural pumice are used as coarse aggregate, and regenerated aggregate is used to replace pumice in equal volume. From macroscopic and microscopic aspects, the replacement rate of recycled aggregate is studied to be 0.30% and 50% respectively. The basic mechanical properties and durability of 100% mixed aggregate concrete are selected out of which the optimum substitution rate is obtained. The experimental results show that the cube compressive strength of mixed aggregate concrete increases gradually with the increase of the replacement ratio of recycled aggregate, and the split tensile strength of mixed aggregate concrete is limited by 30% replacement ratio, which increases first and then decreases. According to the mass loss of concrete, the loss of dynamic modulus of elasticity and the appearance of spalling, it is found that the recycled aggregate concrete with 50% and 70% replacement ratio shows good frost resistance. The content of pore structure is one of the main factors that influence the compressive strength of concrete with the increase of replacement ratio of recycled aggregate and the decrease of pore content in mixed aggregate concrete. The results show that the optimum replacement rate of recycled aggregate is 50%. The particle sizes of waste rubber powder were 20 mesh, 60 mesh, 80 mesh, 100 mesh and 120 mesh, respectively. The mechanical properties and microstructure of mixed aggregate concrete in the early stage were analyzed according to the amount of 3% cement material and 6% ~ 9% addition. The experimental results show that under the condition of the same particle size, the reduction rate of compressive strength of mixed aggregate concrete is increased by waste rubber powder. It is concluded from environmental scanning electron microscope that the interface between rubber powder, recycled aggregate, pumice and cement is a weak area, which is the main reason for the decrease of strength of mixed aggregate concrete.
【学位授予单位】：内蒙古农业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU528

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