Performance Research On Alkali-Activated Fly Ash Cogulation Materials

This paper studies mostly the development principle of intensity of fly ash and the increased calcium fly-ash in alkali through adopting two system: smoke curing and press moulding and analyses the performance of the alkali-activated coagulation materials. Observe hydration products through SEM and analyze micro-structures activated mechanisms.With the variation of their alkali type, content of alkali, fineness, water cement ration, the temperature of curing, the time of curing, moulding press and other factors, nalyze the principle of their intensity. Researches show that:the best content of lime is 10%, the activated effect of NaOH on fly ash stimulating is superior to the effect on sodium silicate, the activated effect of sodium silicate on the increased calcium fly-ash stimulating is superior to the effect on NaOH. When the content of the sodium silicate, modules 1.2, reach 10%, the intensity reach the maximum. The best fineness of fly ash is 630m~2/kg, the best fineness of increased calcium fly-ash is 430 increased calcium fly-ash, when activate two fly in NaOH; The best fineness of fly ash is 630m~2/kg, the best fineness of increased calcium fly-ash is 530 increased calcium fly-ash,when activate two fly in sodium silicate. When alkali activate fly ash and the increased calcium fly-ash, the more the temperature of curing increase, the age of curing increase, the larger the intensity is. By the consideration of intensity and economy, moulding press will be 22.5MPa. The intensity of alkali-activated fly ash brick is higher than common fly ash brick. A little amount of Portland cement can greatly enhance the alkali-activated effect of fly-ash and the increased calcium fly-ash, and improve the performance of the alkali-activated materials, also bring going beyong fold purpose. Alkali-activated materials have a very high anti-acid erosion performance and the coefficient of anti-erosion is two times more than that of cement. The contraction of alkali-activated materials are relatively large, a little amount of the cment added can greatly improve its contraction performance, even equal to the contraction of ordinary cement.Observe the hydration product of alkali-activated fly ash coagulation materials through electronic microscope: fly ash grains surface are corroded in alkali and much hydration product around fly ash grain is abundant and dense. When cement and NaOH or cement and sodium silicate activate fly ash, hydration product structures is further dense.