冻融循环条件下粉煤灰透水混凝土力学及透水特性分析

Mechanics and Pervious Property Analysis of Fly Ash Pervious Concrete under Freeze-thaw Cycle

为了获得良好的透水性能应使砖体内形成较大的孔隙率,需合理控制烧结过程的温度、配制合适的物料比。本文通过冻融循环条件下的实验测试分析研究高碳粉煤灰掺量,烧结温度和砖坯成型压力三个参数对透水混凝土性能的影响。研究结果表明:当高碳粉煤灰掺量持续提高后,劈裂拉伸强度持续减小,而透水系数持续增大,并且保水性也不断升高。当烧结温度升高后劈裂拉伸强度与透水系数具有相反的变化规律。处于高温状态下液相将持续流动并进入砖体内部孔隙中,由此获得更高强度的透水混凝土,同时保水性发生降低。随着成型压力的持续上升,生坯密度先显著增大之后达到一个稳定的状态。当砖坯的成型压力上升后,劈裂拉伸强度持续升高,而透水系数则持续减小,而保水性也持续降低,并且不同成型压力对应的变化幅度也存在较大差异。

In order to obtain good water permeability,a large porosity should be formed in the brick,the sintering process temperature should be controlled reasonably,and the appropriate material ratio should be prepared.In this paper,the influence of three parameters of high carbon fly ash content,sintering temperature and brick-forming pressure on the performance of pervious concrete is studied through the experimental test under the condition of freeze-thaw cycle.The results show that when the content of high carbon fly ash continues to increase,the tensile strength of cleavage continues to decrease,while the permeability coefficient continues to increase,and the water retention also increases.When the sintering temperature increases,the splitting tensile strength and the permeability coefficient have opposite change rules.At high temperature,the liquid phase will continue to flow and enter the internal pores of the brick body,so as to obtain higher strength of pervious concrete and lower water retention.With the continuous increase of forming pressure,the density of green billet first increases significantly and then reaches a stable state.When the molding pressure of the brick increases,the splitting tensile strength continues to increase,while the permeability coefficient continues to decrease,and the water retention also continues to decrease,and the corresponding variation range of different molding pressures is also quite different.