Ⅱ级粉煤灰掺量对胶砂放热及力学影响规律

Influence Rules of The Content of Grade Ⅱ Fly Ash on Heat Release andMechanical Properties of Mortar

粉煤灰作为混凝土中常用的外掺料使用广泛。设计了不同Ⅱ级粉煤灰掺量下胶砂的放热量和力学性能试验方案,通过直接法和间接法对比测定了不同时期的胶砂放热量,并测定了相应的胶砂抗压强度和抗折强度,获得了相应的Ⅱ级粉煤灰掺量—胶砂放热—胶砂强度之间的关系规律。常态的大体积混凝土,建议粉煤灰掺量30%~50%之间,其能够很好地降低放热量,同时又能保证较高的强度;水电站中大体积碾压混凝土,鉴于90d胶砂强度依然能够达到较高的值,建议根据实际条件采用不低于65%的粉煤灰掺量。

Fly ash is widely used as admixture in concrete.In this paper,the experimental scheme of heat release and mechanical properties of mortar with different content of grade II fly ash is designed.The heat release of mortar in different periods is measured by direct method and indirect method,and the corresponding compressive strength and flexural strength of mortar are measured.The relationship between the content of grade II fly ash,the heat release of mortar and the strength of mortar is obtained.For normal mass concrete,it is recommended that the fly ash content be between 30%and 50%,which can reduce the heat release and ensure high strength;for the medium and large volume RCC of hydropower station,considering that the 90 d mortar strength can still reach a high value,it is recommended to adopt the fly ash content of no less than 65%according to the actual conditions.