大掺量粉煤灰高性能混凝土试验研究

针对大掺量粉煤灰混凝土存在的早期强度低、抗冻、抗碳化耐久性不足等问题,通过试验研究,结果表明:大掺量粉煤灰高性能混凝土①宜既掺优质粉煤灰又掺引气型高效减水剂,混凝土为中等标号时可选用32.5等级普通硅酸盐水泥;②为确保达到一定的早期强度和耐久性,普通硅酸盐水泥外加粉煤灰不宜大于胶凝材料总量的50%;③含气量宜为3%-5%,其抗冻标号可达到D100以上,同时掺入激发剂、元明粉和生石灰粉后,强度损失和质量损失有所减小,可进一步改善其抗冻性和耐久性;④可添加1.0%-1.5%碱性激发剂元明粉以提高其早期强度和抗碳化性能;⑤若既掺元明粉又掺生石灰粉作碱性激发剂,则可弥补元明粉对后期强度的不利影响,但生石灰粉的掺量不宜超过5%,掺量太大可能会导致膨胀开裂.以上结果为大掺量粉煤灰高性能混凝土的设计提供了有效途径.

Research on high performance concrete added with high-volume fly ash

The paper studies on the early strength,frost resistance,carbonization of the high volume fly ash concrete(HVFAC).The results show that the high grade fly ash and air entraining water reducing agent can be mixed into HVFAC to improve the performance,with the 32.5R portland cement in medium grade.The quantity of fly ash mixed in blending can't exceed 50% for the stated early strength and durability and the volume of the air entrained is 3%-5% to hold the frost resistant out D100.The loss of strength,mass and frost damage are reduced by mixing with activation agent,Na2SO4 and lime powder.To retain the early strength and avoid carbonization,1.0%-1.5% of alkaline agent can be added.Lime powder can be mixed to offset the later strength,but excess of it(more than 5%) brings on expansion.The author puts forward some improvement suggestions to the effectual approach for improving design of high volume fly ash high performance concrete.