Study On The Performance Of Alkali-activated Fly Ash Mortar

In China,there is a large amount of fly ash and a high annual growth rate,and the large amount of fly ash is seldom fully utilized,which is not only a waste of resourc-es,but also a kind of pollution to the environment.Now to the use of fly ash is limited to Portland cement as admixtures and some building materials products,rarely making fly ash as the main construction materials to use,which is very adverse to the popularized application of fly ash.The reason for limiting the large-scale application of fly ash like silicate cement is due to the low activity of fly ash and the low intensity of early hydration reaction.At present,there are many scholars at home and abroad in the study of alkali-activated materials of fly ash,but it needs certain conditions to obtain good effect,and the preparation process is relatively complex and the cost is relatively high.It is difficult to achieve high strength under normal temperature and rapid early hydration reaction.The main contents of this study are:(1)To study the influence of different factors on the alkali-activated intensity of fly ash mortar,such as curing temperature,slag dosage,curing system,sodium hydroxide solution molarity,the mass ratio of the solution to fly ash,the mass ratio of fly ash to standard sand,the type of activators,and mass ratio of sodium silicate to sodium hydroxide solution.According to the key factors affecting the strength of alkali-activated fly ash mortar,the mixture ratio of high strength and rapid early reaction can be obtained at normal temperature.(2)By scanning electron microscope and mercury injection test,the influence of key factors on the microstructure and the pore structure of alkali-activated fly ash mortar were studied.(3)The effect of different factors on the performance of alkali-activated fly ash mortar was studied.Test results show that: Under normal temperature,the mass ratio of sodium silicate to sodium hydroxide solution is the most important factor on affecting early strength,pore structure,setting time and fluidity of alkali-activated fly ash mortar,and it is the key parameter to obtain a mixture ratio of high strength of alkali-activated fly ash mortar at normal temperature.The curing temperature and slag content can improve the early strength of alkaliactivated fly ash mortar,and the amount of slag has great influence on the setting time and fluidity.The retarder has no effect on the setting time of alkali-activated fly ash mortar,and the water reducing agent does not affect the fluidity of alkali-activated fly ash mortar.