工业废渣用于地下工程止水帷幕的试验

等厚度水泥土搅拌连续墙作为止水帷幕,具有适应地层广、成墙品质好等独特的优点;但在推广过程中的最大障碍是造价过高;若粉煤灰和矿渣等工业废渣替代部分水泥,则其应用范围将大大提高。为测试工业废渣代替水泥的性能,笔者做了大量无侧限抗压强度和渗透性试验。试验结果表明:性能差别不大的情况下,粉煤灰和矿渣可以部分替代水泥;复合水泥土存在最优配合比,对于黏土,最佳掺入比为30%,最佳水固比为0.6;对于砂土,最佳掺入比则为40%,最佳水固比为0.6;总体而言,粉煤灰配合砂土的物理力学性质较优,矿渣则更适合黏土。添加粉煤灰或矿渣的黏土长期强度接近;而添加粉煤灰的砂土强度平均值比添加矿渣大2.4倍,同时更加稳定。添加粉煤灰的黏土和砂土平均渗透系数是添加矿渣的35%左右。

Experimental application of the industrial waste to the waterproof curtain in underground engineering

As one of the waterproof curtains, trench cutting re-mixing deep wall (TRD) possesses unique advantages of fitting most layers and getting good qualities, however, the high cost hinders its popularization. Thus, if cement can be partly substituted by cheaper fly ash, slag and other industrial waste, the application scope of TRD will be greatly enlarged. In order to verify the performance of the cement replaced by industrial waste, the authors conduct a lot of strength and permeability tests. And results show that fly ash and slag can substitute partially for cement and there is an optimal mixture ratio for the composite cement soil. The best mixing ratio and water-solid ratio is 30% and 0.6 respectively for clay, and 40% and 0.6 for sand. Generally, the physical and mechanical properties will be superb when fly ash mixing with sand, while slag is more suitable for clay. The long-term strength of clay is close when adding fly ash or slag, while the average strength of sand after adding fly ash is more stable and 2.4 times larger than that of sand adding slag. In addition, the average permeability coefficient of clay and sand after adding fly ash is about 35% than that of clay and sand adding slag.