大温差盐渍土环境下矿物掺合料混凝土抗裂性能研究

Research on Crack Resistance of Mineral Admixture Concrete Under Large Temperature Difference and Saline Soil Environment

制备了基准组及三组不同掺量的粉煤灰-矿粉混凝土,采用环境试验箱模拟大温差及盐渍土侵蚀环境,研究了混凝土的力学性能和抗裂性能。结果表明:矿物掺合料的掺入降低了混凝土的力学性能,但提高了其力学性能增长速率,还提高了混凝土的抗裂性能;掺15%粉煤灰和20%矿粉的混凝土前期抗压强度增长速率较快,3~14 d的抗压强度平均增长率比基准混凝土高102.46%,28 d的断裂能比普通混凝土高50.67%;含矿物掺合料的混凝土抗折强度增长速率均高于基准混凝土;通过SEM发现,适量矿物掺合料改善了混凝土内部的密实度和孔隙结构,裂缝宽度明显减小。

The reference concrete and three kinds of fly ash-slag concrete with different contents were prepared,and their mechanical properties and crack resistance were studied by using an environmental test chamber to simulate the environment of large temperature difference and saline soil erosion.The results show that the addition of mineral admixtures reduces the mechanical properties of concrete,but increases its growth rate and also improves the crack resistance of concrete.The compressive strength growth rate of concrete mixed with 15%fly ash and 20%slag is faster in the early stage.The average growth rate of compressive strength from 3 d to 14 d is 102.46%higher than that of reference concrete,and the fracture energy of 28 d is 50.67%higher than that of reference concrete.The flexural strength growth rate of the three groups of mineral admixture concrete is generally higher than that of reference concrete.It is found by SEM that the appropriate mineral admixture improves the compactness and pore structure inside the concrete,the crack width is significantly reduced.