Effect Of Metakaolin In Yunnan Province On Properties Of Cement And Concrete

At present,concrete is widely used as building material.Because mineral admixtures such as slag powder,fly ash and silica ash have good filling effect and pozzolanic activity,which can improve the microstructure and macroscopic properties of concrete so mineral admixtures have become an indispensable component in modern concrete technology.The slag powder and fly ash resources in Yunnan Province are scarce,and the processing technology is relatively poor,which is difficult to meet the performance requirements of mineral admixtures,and cannot meet the requirements of concrete.However,the metakaolin resources in Yunnan Province are abundant,and the metakaolin has pozzolanical and micro-aggregate filling effect.The researches have shown that metakaolin can improve the performance of concrete.However,there is a lack of research on metakaolin of Yunnan Province.Therefore,the effects of metakaolin in Yunnan Province on the setting time and the strength of the mortar by replacing the cement with 0%,10%,20% and 30% metakaolin were researched.The influences of metakaolin content on concrete slump,slump flow,setting time and compressive strength were studied by metakaolin single-mixed,metakaolin is mixed with slag powder,metakaolin mixed with slag powder and fly ash.The conclusions are obtainde as follows:(1)The initial setting time and final setting time of cement were shorted obviously by adding metakaolin obtaining from Yunnan Province.With the content increasing the effects become more obvious.However,it meets the requirements of GB/T 175-2007 for setting time.(2)The fluidity of metakaolin cement mortar decreased with the content of metakaolin increasing.The workability of the mortar with metakaolin can improved by adding superplasticizer.Metakaolin in yunnan has good activity and can improve the compressive strength of cement mortar with 28 d.(3)When metakaolin single-mixed,metakaolin mixed with slag powder,metakaolin mixed with slag powder and fly ash,the setting time of concrete was shortened with the dosage of metakaolin increasing,the effect was more obviously,but the results does not inpact the application of matakaolin in concrete.(4)Metakaolin single-mixed,metakaolin with slag powder and fly ash can increase the cubic compressive strength of concrete.The order of improving effects on the compressive strength of concrete are as follows: metakaolinite a mixed with slag powder > metakaolinite single-mixed > metakaolin with slag powder and fly ash.(5)After application in engineering,it is proved the matakaolin in Yunnan Province can be used as mineral admixture in concrete.