Research On Preparation And Performance Of Environment-Protecting Cementitious Materials

In order to reduce resource and energy consumption of the cement industry, alleviate or eliminate environment pollution, environment-protecting cementitious material was put forward based on transformation in the development model of the cement industry. Environment-protecting cementitious material can eliminate a flood of industry wastes, namely industrial residue used to replace part or most of the traditional Portland cement clinker as cement admixture. Research and preparation of environment-protecting cementitious material can promote china’s cement industry towards a path of sustainable development.In this study, fly ash and slag were researched as cement mixture though increasing their content to make environment-protecting cementitious material. The reactivity of fly ash was enhanced by microwave radiation, the content of which in cementitious material system can be increased with fly ash irradiated by microwave instead of cement clinker. Activated alumina of metakaolin and calcium sulfate anhydrate of sulpho-aluminate cement can benefit to form more ettringite, and then promote the hydration of the cement clinker. Metakaolin and sulpho-aluminate cement were added in large charge slag environment-protecting cementitious material and can improve its early strength.In addition, the high volume fly ash and slag cementitious materials were cured by microwave radiation in this paper. The influence of mortar strength of two cementitious materials conserved by microwave radiation was discussed systematiclly.The results are as follows:(1)Microwave irradiation can improve the reactivity of fly ash obviously. Different activation effects to the activity of fly ash can be obtained by different microwave radiation power and time. Among them, the activity of fly ash reaches the maximum by radiated with450W for10minutes. The best microwave radiation parameters applying to fly ash can be determined by the results of mortar strength tests.(2)Testing the water requirement of normal consistency and setting time of environment-protecting cementitious material containing large volume fly ash, combined with the results of mortar strength, show that42.5strength grade environment-protecting cementitious material can be prepared when the equal amount of cement clinker is replaced with fly ash radiated by microwave reaching30percent. And32.5strength grade environment protection type of cementitious materials can be prepared when the amount of fly ash stimulated by microwave radiation reaching40and50percent instead of cement clinker.(3) It can improve the early strength of environment-protecting cementitious material by adding a few of metakaolin and sulpho-aluminate cement. Research show that32.5strength grade large volume slag environment-protecting cementitious materials can be prepared by adding proper metakaolin and sulpho-aluminate cement when the amount of slag reaches80percent.(4)Microwave curing can improve the early mortar strength of high volume fly ash and slag cementitious materials. High volume fly ash cementitious material is irradiated by microwave with150W curing10minutes, and large amount of slag cementitious material is irradiated by microwave with300W curing10minutes, which shows their mortar strength increased most significantly. The optimal microwave curing parameters can be determined by the results of mortar strength tests.