粉煤灰对桥梁混凝土抗渗性能的影响规律研究

为研究粉煤灰对桥梁混凝土抗渗性能的影响,制备了不同粉煤灰掺量的混凝土样品,测试分析了桥梁混凝土抗压强度、孔隙结构、渗透高度和抗氯离子渗透性能随粉煤灰掺量和养护龄期的变化规律。研究结果表明:(1)当桥梁混凝土养护龄期为7d时,桥梁混凝土的抗压强度随着粉煤灰掺量的增多而逐渐降低;当混凝土龄期大于28d时,桥梁混凝土的抗压强度在粉煤灰掺量为30%左右时最大。(2)粉煤灰掺量为30%时,桥梁混凝土密实度达到最大,此时其内部小孔隙增大而大孔隙减小。(3)桥梁混凝土抗氯离子渗透系数随着粉煤灰掺量的增大先减小后增大,在粉煤灰掺量为30%时取得最小值。

Study on the Influence of Fly Ash on Impermeability of Bridge Concrete

In order to study the influence of fly ash on the impermeability of bridge concrete, concrete samples with different fly ash content were prepared. The variation of compressive strength, pore structure, penetration height and chloride ion penetration resistance of bridge concrete with the amount of fly ash and the age of curing were tested and analyzed. The results showed that:(1)When the concrete curing age of the bridge was 7 d, the compressive strength of the bridge concrete decreased with the increase of the fly ash content. When the concrete age was greater than 28 d, the compressive strength of the bridge concrete would be the largest when the fly ash content was about 30%.(2)When the amount of fly ash was 30%, the concrete compactness of the bridge reached to the maximum. At this time, the small pores increased and the large pores decreased.(3) The chloride ion permeability coefficient of bridge concrete decreased firstly and then increased with the increase of fly ash content, and the minimum value was obtained when the fly ash content was 30%.