胶凝材料颗粒匹配对喷射混凝土强度和抗氯离子渗透性的影响

Effect of particle matching of cementitious materials on strength and chloride penetration resistance of tunnel shotcrete

通过改变矿物掺合料的细度和掺量,以净浆流动度表征浆体的工作性,对喷射混凝土中胶凝材料的颗粒匹配程度进行了评价。对不同配合比喷射混凝土进行了力学性能和氯离子渗透试验,研究了胶凝材料颗粒匹配对喷射混凝土强度和抗氯离子渗透性的影响,分析了其影响机理。研究结果表明:胶凝材料颗粒匹配不同时,其净浆流动性存在较大差异。I级粉煤灰颗粒较细,其发挥的滚珠效应对提高浆体的流动性所起作用最大。胶凝材料的细度和颗粒匹配等特征影响了矿物掺合料的活性和反应程度,进而对结构密实性造成影响。水泥、I级粉煤灰与S95矿渣的搭配恰好发挥了粉体材料颗粒间的互补作用,对应的喷射混凝土试件微观结构密实,强度较高,自由氯离子浓度最低。微观测试结果表明,胶凝材料颗粒的匹配程度对净浆试件内部结构的致密程度造成影响,佐证了净浆流动度和喷射混凝土宏观性能的试验结果。

The fineness and content of mineral admixture were changed in this study.The fluidity was used to evaluate the workability of the slurry,and the particle matching degree of cementitious materials in shotcrete was evaluated.The mechanical properties and chloride ion penetration tests of shotcrete with different mix proportions were carried out.The effect of particle matching of cementitious materials on the strength and chloride ion permeability of sprayed concrete was studied,and the influence mechanism was analyzed.The results show that there are great differences in the fluidity of the slurry when the particles of the cementitious materials are not matched.Grade I fly ash has fine particles,and its ball bearing effect plays a great role in improving the fluidity of the slurry.The fineness and particle matching of cementitious materials affect the activity and reaction degree of mineral admixtures,and then affect the structural compactness.The combination of cement,grade I fly ash and S95 slag just plays a complementary role among the particles of powder materials.The corresponding sprayed concrete specimen has dense microstructure,high strength and the lowest free chloride ion concentration.The microscopic test results show that the matching degree of cementitious material particles has an effect on the compactness of the internal structure of the paste specimen.The results of the microscopic tests confirm the experimental results of the fluidity of the slurry and the macroscopic properties of the sprayed concrete.