掺粉煤灰碾压混凝土强度同抗冻性相关性研究

Study on Correlation Between Strength and Frost Resistance of RCC With Fly Ash

在碾压混凝土重力坝建设中,多采用掺入粉煤灰替代部分水泥的方式降低混凝土硬化过程中产生水化热速率过快、在内部形成热聚集导致混凝土膨胀产生应力过大而造成的混凝土开裂,提高施工质量。相关方面的研究已经很多,但粉煤灰的掺入量对碾压混凝土强度和抗冻性之间关系研究较少。取在基准碾压混凝土配合比中水泥用量的20%、30%、40%和60%用粉煤灰替代后形成对比测试体作为研究对象,先利用试验结果分析不同替代掺量下强度同龄期关系,后利用试验分析不同龄期下各试验体冻融循环质量损失率。确定碾压混凝土强度同粉煤灰掺量之间关系受龄期影响。抗冻性同强度变化具有相关性,但随粉煤灰掺量增加质量损失率变化强于强度变化,在工程中应考虑早期强度和粉煤灰掺量的共同影响。

In the construction of roller compacted concrete gravity dam,fly ash is often used to replace part of cement to reduce the excessive hydration heat rate in the concrete hardening process,which leads to the concrete cracking caused by excessive stress caused by the expansion of concrete,and improve the construction quality.There have been many researches in related fields,but there are few researches on the relationship between strength and frost resistance of roller compacted concrete with fly ash content.In this paper,20%,30%,40%and 60%of cement in the benchmark RCC mix ratio were replaced by fly ash,which was used as the research object.First,the test results were used to analyze the relationship between strength and age,and then the test was used to analyze the freeze-thaw cycle mass loss rate of each test body at different ages.It was determined that the relationship between RCC strength and fly ash content was affected by age.Frost resistance was related to strength change,but with the increase of fly ash content,the change of mass loss rate was stronger than the change of strength,so the joint influence of early strength and fly ash content should be considered in engineering.