预应力下风积沙混凝土耐久性能研究

发布时间：2018-04-26 13:45

本文选题：风积沙混凝土 + 预应力损伤　；参考：《内蒙古农业大学》2017年硕士论文

【摘要】：混凝土在服役期间,受到意外撞击、震动和地震等偶然外加荷载作用而出现损伤,导致处于冻融环境下和氯盐侵蚀下的风积沙混凝土耐久性变差。所以,风积沙混凝土在预应力损伤后具有的耐久性研究非常重要。在进行耐久性试验之前,先进行力学损伤试验,具体可分为三个阶段:阶段一:施加预应力。采用万能试验机外加载的方式施加预应力,施加预应力之前以及之后用非金属超声波检测仪测定试件气干状态下的超声波波速,通过计算损伤变量和反复加载,最终得到未受预应力的C25风积沙混凝土和损伤度分别为0.0～0.1与0.1～0.2以及0.2～0.3预应力损伤风积混凝土。阶段二:对被预应力损伤的风积沙混凝土展开相应实验。根据相关文件GB/T50082-2009,即混凝土的耐久性与长期性试验规定,在冻融循环实验中使用的是文件内的"快冻法",并且在评价指标上选择的是该混凝土的质量变换与相对动弹性模量。试验结果表明:相较之下,被预应力损伤的混凝土在抗冻融性方面的变化是具有梯度规律的。如果该混凝土的损伤度达到0.0～0.1,那么它在冻融劣化方面的规律就和基准风积沙相差不大,其抗冻性在损伤度大于0.1之后,就会出现明显降低。阶段三:风积混凝土在被预应力损伤之后的干湿循环研究。该研究主要是针对该混凝土的抗氯盐侵蚀性。以质量变化率和相对动弹性模量作为评价指标来综合表征预应力损伤下风积沙混凝土抗氯盐侵蚀性能。结果表明:与基准风积沙混凝土相比,预应力下风积沙混凝土抗氯盐侵蚀性能呈现线性变化规律,损伤度为0.0～0.1的风积沙混凝土试件抗氯盐侵蚀性能略有下降,可忽略损伤度对其的影响;如果损伤度大于0.1,那么其抗氯盐侵蚀性就会出现明显降低。本文在研究了风积沙混凝土的抗冻融性以及氯盐侵蚀性之后,以此为依据构建了相应的演化方程,对针对被预应力损伤的风积沙混凝土处于氯盐中所具有的抗侵蚀性,之后将此当做该混凝土耐久性评价的理论依据,具有很大的意义。
[Abstract]:During the period of service, the concrete is damaged by accidental impact, vibration and earthquake, which results in the deterioration of the durability of the wind-sand concrete under freezing and thawing environment and chlorine salt erosion. Therefore, it is very important to study the durability of eolian sand concrete after prestress damage. Before durability test, mechanical damage test is carried out, which can be divided into three stages: stage one: applying prestress. The prestressing force is applied by the universal testing machine, and the ultrasonic wave velocity in the air-dry state of the specimen is measured by the non-metallic ultrasonic detector before and after the prestress is applied. The damage variable is calculated and the repeated loading is carried out. Finally, the unprestressed C 25 aeolian sand concrete and the damage degree are 0. 0. 1, 0. 1, 0. 2 and 0. 2 ~ 0. 3 respectively. Stage two: the corresponding experiments are carried out on the eolian sand concrete damaged by prestress. According to the relevant document GB / T 50082-2009, that is, the durability and long-term test of concrete, the "quick freezing method" is used in the freeze-thaw cycle experiment, and the quality shift and relative dynamic elastic modulus of the concrete are selected in the evaluation index. The experimental results show that, by comparison, the change of freeze-thaw resistance of prestressed concrete has gradient law. If the damage degree of the concrete reaches 0.00. 1, the law of freeze-thaw deterioration is not different from that of the standard aeolian sand, and the frost resistance of the concrete will decrease obviously when the damage degree is greater than 0.1. Stage three: dry and wet cycle of wind-induced concrete after prestress damage. This study is mainly aimed at the chloride corrosion resistance of the concrete. The rate of mass change and the relative dynamic modulus of elasticity are taken as the evaluation indexes to comprehensively characterize the chloride corrosion resistance of wind-sand concrete under prestress damage. The results show that compared with the standard aeolian sand concrete, the chloride corrosion resistance of the prestressed concrete under the wind sand has a linear variation rule, and the chloride corrosion resistance of the wind sand concrete with damage degree of 0.00. 1 is a little lower than that of the standard eolian sand concrete. If the damage degree is greater than 0.1, the resistance to chloride corrosion will be significantly reduced. After studying the freeze-thaw resistance and chloride erosion of eolian sand concrete, a corresponding evolution equation is constructed based on which the corrosion resistance of eolian sand concrete with prestressing damage in chloride salt is studied. It is of great significance to take this as the theoretical basis for durability evaluation of 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

【参考文献】