Effect of calcium addition at high temperature on fly ash´s activation character

The surface network structure of fly ash modified by calcium addition at high-temperature was analyzed by NMR, and K_a method-(ICP-AES) rapid evaluation was used too. By activity exhibition of modified fly ash in cement paste, the effect of calcium addition course at high-temperature on fly ash´s activity characteristics was studied. The results indicate: modified by calcium addition at high-temperature, fly ash´s early K_a value improvement, and ratio of activated Al₂O₃/SiO₂ was more than twice the average ratio of original fly ash, indicating the calcium addition course at high-temperature was not only destructive on Si-O bond, its destructive power on Al-O bond was also more apparent. Under the environment of cement paste, modified fly ash´s reaction took place rapidly at early stage of cement hydration, and continually to consume Ca(OH)₂ produced by cement hydration.