地铁车站抗渗防水混凝土配合比正交试验研究

Study on Orthogonal Test of Mixing Ratio of Anti-seepage and Waterproof Concrete in Subway Station

针对地铁车站混凝土结构渗漏技术难题,以合肥轨道交通4号线为工程背景,采用正交试验方法,确定考虑粉煤灰、矿粉、膨胀剂、纤维素纤维等混掺组分的试验方案;开展混凝土试样的物理力学特性、限制膨胀率、相对渗透系数、低场核磁共振孔隙结构等试验,分析主要混掺材料掺量对其抗渗防水混凝土主要性能的影响,以及孔隙结构特征与相对渗透系数关系。试验结果表明:粉煤灰、矿粉在10%~20%掺量能提高混凝土28 d抗压强度;当膨胀剂掺量为8%时,混凝土28 d抗压强度降低;纤维素纤维在0.9~1.5 Kg/m3掺量范围内,28 d劈裂抗拉强度随掺量增加而增加;优化得出抗渗防水混凝土配合比为:水泥:粉煤灰:矿粉:膨胀剂:砂:石子:水:纤维素纤维:减水剂=1:0.214:0.214:0.086:2.749:4.123:0.636:0.005:0.012,相对于基准组28 d抗压、劈裂抗拉强度分别提高17%、14.6%,小孔隙面积减少52.5%,孔隙度降低55%,相对渗透系数降低32%。

In view of the technical problem of leakage of the concrete structure of the metro station,the orthogonal test method is adopted to determine the test scheme considering the mixed components such as fly ash,mineral powder,expansion agent and cellulose fiber,taking Hefei Rail Transit Line 4 as the engineering background.Tests were carried out on the physical and mechanical properties,limited expansion rate,relative permeability coefficient and low field NMR pore structure of concrete samples,to analyze the influence of the content of main mixed materials on the main properties of impermeable and waterproof concrete,as well as the relationship between pore structure characteristics and relative permeability coefficient.The test results show that the content of fly ash and mineral powder at 10%~20%can improve the compressive strength of concrete for 28 days;when the expansion agent content is 8%,the compressive strength of concrete decreases on 28 days;when the parameters of cellulose fiber range from 0.9 to 1.5 kg/m3,the 28d splitting tensile strength increases with the increase of the content of cellulose fiber;optimization obtains waterproof impermeability of concrete is:cement,fly ash,mineral powder,expansive agent:sand,gravel,water,cellulose fiber,water reducing agent=1:0.214:0.214:0.086:2.749:4.123:0.636:0.005:0.012,relative to the baseline group 28 d compressive strength,splitting tensile strength increased by 17%and 14.6%respectively,small pore size decreased by 52.5%,55%lower porosity and relative permeability coefficient reduced by 32%.