新型疏水剂对大坝混凝土性能影响研究

Influence of new hydrophobic agent on dam concrete property

寒冷地区混凝土大坝的渗水和冻融劣化是造成坝体破坏形成决口、甚至溃坝等风险事件的主要原因,对坝体混凝土进行疏水处理是工程实践中迫切需要解决的问题。应用表面改性后的沸石粉(YA)作为新型疏水剂对混凝土进行疏水处理,制备水胶比为0.5,YA掺量分别为0,2%,3%和4%的疏水混凝土,研究疏水混凝土的力学与抗冻性能;同时利用吸水试验和压汞试验(MIP)测定混凝土的孔隙结构,通过分析孔径分布特征探究YA改善混凝土各项性能的机理。研究发现:YA的掺入能够增加过渡孔(无害孔)含量并抑制大孔(有害孔)的发育,改善了混凝土内部孔隙网络,进一步抑制水及溶液的侵入,从而显著提高了混凝土的力学性能、吸水性能和抗冻性能。

Water seepage and freeze-thaw deterioration of concrete dams in cold areas is the main reason for safety risks such as dam failure,breach and even dam break.The hydrophobic treatment of dam concrete is an urgent problem to be solved in engineering practice.A novel hydrophobic agent named YA(Zeolite powder after surface modification)was applied to the hydrophobic treatment of concrete in this paper.The water-binder ratio of concrete specimens was 0.5,and four kinds of YA content(0,2%,3%,and 4%)were designed to study the mechanical properties and freeze-thaw resistance.Meanwhile,the water absorption test and mercury intrusion method(MIP)were carried out to obtain the pore structure,and the pore size distribution was used to analyze the improving mechanism of the concrete induced by YA.The results showed that the hydrophobic agent YA improved the internal pore network of concrete by increasing the number of transition pores and decreasing the number of macro pores,and further inhibited the intrusion of water and solution.The mechanical properties,water absorption and freeze-thaw resistance of the concrete were improved significantly.