干旱气候下不同养护方式对混凝土抗裂性能的影响

Effect of Curing Method on Crack Resistance of Concrete in Arid Climate

西北地区干旱少雨,蒸发量大、昼夜温差大等恶劣的气候环境易导致混凝土开裂,合理的养护方式可提供混凝土硬化过程中必要的温湿度条件,提高混凝土抗裂性能。为研究干旱气候下养护方式对混凝土抗裂性能的影响,对混凝土裂缝宽度、开裂时间、裂缝长度和裂缝数目进行了统计和分析。结果表明:干旱地区恶劣气候条件易导致混凝土产生干缩裂缝,若不采取适宜的养护措施,在混凝土拆模后的一段时间内会造成混凝土开裂。试验发现:在恶劣气候条件下,塑料薄膜包裹养护、洒水养护等常规养护措施难以满足混凝土硬化时所需的温湿度条件,抗裂性能较差;蒸汽养护可有效防止混凝土早期开裂,亦可减少裂缝数目和抑制裂缝宽度的发展,提高混凝土抗裂性能。研究得出蒸汽养护方式可为特殊环境(干旱)下的混凝土预防开裂提供借鉴。

Severe climate conditions in northwest China,such as drought,insufficient rain,large evaporation and large temperature difference between day and night are liable to lead to concrete cracking.Reasonable curing method provides necessary temperature and humidity conditions during concrete hardening and enhances the cracking resistance of concrete.In order to obtain the effect of curing method on the crack resistance of concrete in arid climate,we made a statistical analysis on the crack width,crack time,crack length and crack number of concretes.Results demonstrated that dry shrinkage cracks would occur after detaching the mold plates unless proper curing measures are taken.Under severe weather conditions,conventional curing measures such as plastic film wrapping and sprinkler curing could not meet the temperature and humidity conditions required for concrete hardening,resulting in poor crack resistance.Steam curing could effectively prevent early cracking of concrete,reduce the number of cracks and inhibit the development of crack width,and improve the crack resistance of concrete.