冷热循环作用下EVA对混凝土孔结构的影响

模拟中国西部地区大温差环境,研究了冷热循环作用下乙烯醋酸乙烯共聚物(ethylene-vinyl acetate copolymer,EVA)对混凝土抗压强度及孔结构的影响,并分析了混凝土强度与孔结构之间的关系.结果表明:质量分数为8%的EVA即可降低混凝土早龄期的汞压入量和混凝土孔隙率,且孔结构更均匀;随着冷热循环次数的增加,EVA的膜结构与浆体或骨料的黏结性能发生劣化,表现为混凝土中50~200nm孔的比例增加;EVA可改善混凝土的微观结构,有效细化混凝土的孔径分布,降低混凝土内部损伤速率,使混凝土抗压强度降低速率在冷热循环作用下有所减缓.

Effect of EVA on Pore Structure of Concrete under Thermal Cooling Cycling Curing

Large temperature difference environment in China's west region was simulated,the influence of EVA on concrete compressive strength and pore structure under the thermal-cooling cycling curing was studied,and the relationship between strength and pore structure change was established.The results show that 8%of EVA decreases the amount of mercury intrusion in the early age,that is,the porosity is reduced and the concrete pore structure is more uniform.With the increase of the times of the thermal-cooling cycling,the adhesion between the EVA film structure and the slurry or aggregates will deteriorate,which is manifested by an increase in porosity of 50 to 200nm in the concrete.At the same time,EVA can improve the microstructure,effectively refine the pore size distribution of concrete,and reduce the internal damage rate of concrete so that the strength reduction rate of concrete decreases after thermal-cooling cyclings.