预制混凝土早强免蒸养外加剂试验研究

发布时间：2018-01-20 07:31

本文关键词： 预制混凝土聚羧酸减水剂早强剂坍落度抗压强度　出处：《山东建筑大学》2017年硕士论文　论文类型：学位论文

【摘要】：在我国当前现代化飞速发展的形势下,预制混凝土已经成为混凝土与水泥制品行业最重要的发展方向之一。但由于预制混凝土早期强度普遍不高,导致模具周转率较低,极大影响了生产效率。蒸汽养护作为目前常用的提高早期强度的技术之一,却存在着有害气体排放,构件裂缝的产生和后期强度损失等问题。因此,研究预制混凝土免蒸养早强技术可避免蒸养带来的问题,并提高生产效率,节约成本,对住宅产业化的发展有着重要意义。聚羧酸减水剂有减水率高、提高强度增长速率等优点;早强剂能够加快混凝土凝结、硬化的速度,并且价格通常较低,尤其是冬季需要采用掺加早强剂的方法提高混凝土早期强度。论文目标在于主要通过对早强型聚羧酸减水剂和早强剂两方面结合的外加剂研究,得到最优配合比,以满足C40预制混凝土在各种养护温度下免蒸养而早期强度达到拆模强度的工程要求。通过对酸醚比、甲基丙烯磺酸钠替代率、合成催化剂和引发剂掺量分别的单一变量试验研究,找到了流动性和抗压强度随各因素的变化规律,并且通过分析,分别确定了四个重要因素的最佳值,在此基础上合成PC-ZQ型早强型减水剂。从水泥适应性、水泥砂浆流动性和水泥砂浆抗压强度三个方面将PC-ZQ减水剂与标准型减水剂和某市售早强减水剂进行对比。通过五组早强剂单掺试验,探索混凝土流动性与抗压强度分别随硫代硫酸钠,甲酸钙,三乙醇胺,亚硝酸钠和硫酸钠掺量变化的规律,选取三种较好的早强剂进行复配,通过正交试验确定复合早强剂的最佳配比,并寻求各因素之间的关系。通过试验探讨不同季节养护条件下对应的C40预制混凝土最优配合比,分别研制对应于春秋季的ZQ-C和冬季的ZQ-D两种复合外加剂产品。为进一步节约成本,通过调整矿物掺合料比例,揭示坍落度与抗压强度随矿物掺合料配比变化的基本规律。结果表明:在夏季养护温度下,达到了不掺加早强剂仅依靠PC-ZQ早强聚羧酸减水剂即可满足早强要求的水平。最终通过检测,不同季节温度养护件下的分别对应的最优配合比早强混凝土都能达到研究目标要求。
[Abstract]:With the rapid development of China's current modernization, precast concrete has become one of the most important development directions in the field of concrete and cement products, but the early strength of precast concrete is generally low. Steam curing, as one of the commonly used techniques to improve the early strength, has harmful gas emissions. Therefore, the study of precast concrete no-steaming early strength technology can avoid the problems caused by steam maintenance, and improve the production efficiency and save the cost. It is of great significance to the development of housing industrialization. Polycarboxylic acid water reducer has the advantages of high water reducing rate and increasing strength growth rate. Early strength agents can speed up the setting and hardening of concrete and are often cheaper. Especially in winter, it is necessary to use the method of adding early strength agent to improve the early strength of concrete. The aim of this paper is to study the admixture of early strength polycarboxylic acid superplasticizer and early strength agent. The optimum mix ratio was obtained to meet the engineering requirements of C40 precast concrete under various curing temperatures without steaming and early strength to reach the demoulding strength. The substitution rate of sodium methallyl sulfonate to acid ether ratio was obtained. The single variable experimental study of the amount of synthetic catalyst and initiator respectively found the variation of fluidity and compressive strength with each factor and determined the best value of four important factors by analysis. On this basis, PC-ZQ type early strength water reducer was synthesized. The fluidity of cement mortar and compressive strength of cement mortar were compared between PC-ZQ water reducing agent and standard water reducing agent and early strength water reducing agent. The flow and compressive strength of concrete varied with the content of sodium thiosulfate calcium formate triethanolamine sodium nitrite and sodium sulfate respectively. The optimum proportion of the composite early strength agent was determined by orthogonal test, and the relationship between various factors was sought. The optimum mix ratio of C40 precast concrete under different season curing conditions was discussed through the experiment. Two kinds of compound admixtures, ZQ-C in spring and autumn and ZQ-D in winter, were developed respectively. In order to further economize the cost, the ratio of mineral admixture was adjusted. The basic law of slump and compressive strength changing with the ratio of mineral admixture is revealed. The results show that: at summer curing temperature. Reached the level of no addition of early strength agent only rely on PC-ZQ early strength polycarboxylic acid water reducer can meet the requirements of early strength. Finally through the detection. The corresponding optimum mix ratio of early strength concrete under different season temperature curing parts can reach the research goal.
【学位授予单位】：山东建筑大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU528.042

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