聚羧酸减水剂对复掺水工混凝土耐久性的影响研究

发布时间：2018-11-17 11:09

【摘要】：严寒地区混凝土坝的抗冻耐久性是决定大坝寿命的重要影响因素。为了提高该地区混凝土坝的抗冻性能,加入引气剂和减水剂等外加剂是主要措施之一。本文以尼尔基水利工程溢流坝段混凝土配合比设计为工程背景,在混凝土中加入聚羧酸减水剂,并添加大比例粉煤灰和矿粉,制备出适合严寒地区高抗冻性、抗碳化性、低水化热和经济性好的大坝混凝土。通过试验,在普通水泥砂浆和C20混凝土中加入0.6%、0.8%、1.0%、1.2%聚羧酸减水剂,分析其对水泥砂浆和混凝土物理力学性能的影响,试验结果表明:加入聚羧酸后,混凝土保坍性好,抗压强度均有所上升,在1.0%时抗压强度最高,达到49.1MPa。在聚羧酸掺量1.0%比例下,制备了单掺粉煤灰20%、30%、40%和按照8:2和6:4比例复掺粉煤灰、矿粉共九组27个C20混凝土试件,试验结果表明:无论是单掺和复掺混凝土试件强度均满足设计强度要求,但复掺情况下随着矿粉比例增加,混凝土强度较单掺提高,最大可提高15%。对添加1%比例聚羧酸减水剂情况下,单掺粉煤灰40%、粉煤灰32%和矿粉8%、粉煤灰24%和矿粉16%三种情况下,C20混凝土的碳化深度、水化放热和抗冻性等耐久性能影响进行研究,掺粉煤灰24%矿粉16%混凝土在以上三个试验中综合效果是最好。最后以尼尔基水电枢纽溢流坝段配合比为比较对象,通过水泥用量、用水量和砂率三个因素进行正交实验,优化了聚羧酸C20混凝土配合比设计参数。掺入聚羧酸减水剂、粉煤灰和矿粉较尼尔基水电枢纽溢流坝段配合比可节约水泥用量41.7%,可节约混凝土成本约17.3%。
[Abstract]:The durability of concrete dam in cold area is an important factor to determine the life of dam. In order to improve the frost resistance of concrete dams in this area, adding air entraining agent and water reducing agent is one of the main measures. Based on the concrete mix design of overflow dam section of Nierji water conservancy project, adding polycarboxylic acid water-reducing agent in concrete and adding a large proportion of fly ash and mineral powder, the high frost resistance and carbonization resistance were prepared in this paper. Low hydration heat and good economy of dam concrete. Through experiment, adding 0.6% 0.8% polycarboxylic acid water reducer to ordinary cement mortar and C20 concrete, and analyzing its influence on physical and mechanical properties of cement mortar and concrete. The test results show that the concrete with polycarboxylic acid has good collapsibility and high compressive strength, and the compressive strength is the highest at 1.0, reaching 49.1 MPA. Under the proportion of 1.0% polycarboxylic acid, a total of 27 C20 concrete specimens of nine groups were prepared, which were composed of 20% fly ash and 40% fly ash, and were mixed with fly ash at 8:2 and 6:4 proportions. The test results show that both the strength of concrete and the strength of concrete can meet the requirements of design strength, but with the increase of mineral powder ratio, the strength of concrete can be increased by 15%. In the case of adding 1% polycarboxylic acid water reducer, the carbonation depth of C20 concrete is only 40% with fly ash, 32% with fly ash and 8 with mineral powder, 24% with fly ash and 16% with mineral powder. The effects of hydration heat release and frost resistance on the durability of concrete are studied. The comprehensive effect of fly ash 24% mineral powder 16% concrete is the best in the above three tests. Finally, taking the proportion of overflow dam section of Nierji Hydropower Project as the comparison object, the design parameters of polycarboxylic acid C20 concrete mixture ratio are optimized by orthogonal experiments of cement dosage, water consumption and sand ratio. The mixing ratio of fly ash and mineral powder with polycarboxylic acid water reducer can save 41.7 cement consumption and 17.3 percent of concrete cost compared with the proportion of overflow dam section of Nierji Hydropower Project.
【学位授予单位】：长春工程学院
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TV431

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