改性轻骨料混凝土高温抗压性能及微观结构

Compressive Properties and Microstructure of Modified Lightweight Aggregate Concrete after Exposure to Elevated Temperatures

采用骨料表面裹覆处理措施改善轻骨料混凝土抗高温爆裂性能,设计了2类改性陶粒混凝土,测试了200,400,600,800,1 000,1 200℃高温作用后改性陶粒混凝土的高温爆裂情况及相对残余抗压强度.通过扫描电镜(SEM)观察了高温后改性陶粒混凝土中骨料-水泥界面过渡区的微观结构.结果表明:改性陶粒混凝土的抗高温爆裂性能较普通陶粒混凝土和普通混凝土提升显著.随着温度的升高,改性陶粒混凝土残余抗压强度不断劣化;在1 200℃高温后,普通陶粒混凝土严重爆裂,而改性陶粒混凝土仍有25%~35%的相对残余抗压强度.同时探讨了改性轻骨料混凝土耐高温性能的作用机理.

Resistance of lightweight aggregate concrete to thermal spalling was improved by coating the surface of the aggregates. Two types of modified clay ceramsite concretes were designed. Spalling and com- pressive strength of the modified concrete specimens after exposure to 200,400,600,800,1 000,1 200 ℃ were tested. And the deterioration processes of interracial transition zone between aggregate particles and cement matrix in the modified concrete specimens after exposure to high temperatures were investigated by using scanning electron microscope. The results show that the modified concrete specimens have much bet- ter resistance to elevated temperature spalling than that of both ordinary lightweight aggregate concrete and ordinary concrete specimens. As the temperature increases, the residual compressive strength of the modified concrete specimens reduses slowly. After 1 200 ℃, the ordinary lightweight aggregate concrete specimens have spalled completely. However, the modified concrete specimens still have approximately 25 % to 35% of the cube compressive strength remained. Also the mechanism behind the improvement of the spalling resistance was discussed.