Study On High Temperature Curing Effect On Microstructure And Mechanical Proper Of The Composite Cementitious Materials About Cement And Ultrafine Ash

The most critical technology of mass concrete structure is how to decrease temperature rise of concrete, adding a lot of fly ash is one of the effective ways to reduce the temperature rise of the internal temperature, but the amount of fly ash can cause the early strength of concrete, and the construction period is prolonged. At present, fly ash has become scarce concrete raw materials in Beijing, Shenzhen and other major cities. The mechanical excitation method of fly ash will further ground, is an effective means to stimulate the activity of fly ash, Is also a significant way to improve the utilization of fly ash.This paper takes the interna l temperature environment of mass concrete as the working condition of the background, and sets high temperature curing of 50℃, taking the composite cement paste and composite cement mortar as the research object. The hydration properties, mineral composition, pore structure, microstructure and mechanical properties of the composite cementitious materials at different temperatures were studied. systematic research on influence of curing temperature on cement and superfine fly ash composite cementitious material hydration hardening process. The results show that:Under high temperature curing condition, ultra fine fly ash can improve the chemical binding water content of composite cementitious materials, on the early hydration of cement has a significant role in promoting. With the increase of the amount of fly ash, the more obvious the effect is. The addition of ultra- fine fly ash only affects the total amount of Ca(OH) 2, but the main hydration products of the cement are generated, but it does not affect the type of cement hydration products.Early high temperature curing, the fine fly ash in hydration early stage has the functio n of the refinement of the pore structure, the increase of the compactness and the hydration of cement. In a certain range,the effect of the refinement of the structure of the fine coal is improved by increasing the amount of superfine fly ash. High temperature curing can make the cement and superfine fly ash composite cementitious material hydration and hardening advance. In the shorter age,it can make the compound cementitious material cement hydration to a certain degree.Under high temperature curing co ndition, the ultra fine fly ash can obviously improve the early compressive and flexural strength of the composite cementitious material. The bigger the amount of fly ash, the more obvious the intensity is increased.