偏高岭土掺量对水泥净浆、砂浆性能的影响试验

Test on the influence of the content of metakaolin on the performance of cement paste and mortar

以广西高岭土矿为原料,通过一定温度煅烧、使其脱水形成白色粉末状的偏高岭土,利用煅烧所得产品,通过等量取代水泥用量的方式,对比研究了偏高岭土净浆、硅灰净浆及水泥净浆7、28 d的抗压、抗折强度关系和不同偏高岭土类型、掺量的砂浆7、28 d抗压、抗折强度的变化规律。结果表明:所制得的偏高岭土产品能够有效提升净浆试件的抗压、抗折强度,且当900℃下煅烧2 h的偏高岭土和硅灰掺量均为水泥用量的15%时,其性能提升作用甚至优于硅灰;能够有效提升砂浆试件的抗压、抗折强度,且当煅烧温度在750~800℃范围内,煅烧时间为3~4.5 h范围内所制得的偏高岭土砂浆性能最好。偏高岭土掺量对砂浆试件的抗压强度影响不明显,对中后期抗折强度具有一定积极作用。因此,将适量的偏高岭土掺入水泥净浆、砂浆中能够一定程度上提升结构强度性能。

Guangxi kaolin ore is used as raw material,calcined at a certain temperature and dehydrated to form a white powdery metakaolin.Using the calcined product,the method of replacing the cement amount with the same amount is used to compare the metakaolin pure slurry and silica fume pure slurry.And the relationship between the compressive and flexural strength of the cement paste 7 d and 28 d,and the change law of the compressive and flexural strength of different types of metakaolin and the mixed amount of mortar 7 d and 28 d.The results show that the metakaolin product prepared in this experiment can effectively improve the compressive and flexural strength of the pure slurry test strip,and when the content of metakaolin and silica fume is 15%of the cement content when calcined at 900℃for 2 h,its performance improvement effect is even better than silica fume.It can effectively improve the compressive and flexural strength of the mortar test strip,and it can be obtained when the calcination temperature is within the range of 750~800℃and the calcination time is within the range of 3~4.5 h.The metakaolin mortar has the best performance.The content of metakaolin has no obvious effect on the compressive strength of mortar test strips,and has a certain positive effect on the flexural strength in the middle and late stages.Therefore,mixing a proper amount of metakaolin into cement paste and mortar can improve the structural strength performance to a certain extent.