现浇钢筋砼楼板裂缝产生的原因及防治措施

Cause and prevention against cracks on the cast-in-situ reinforced concrete floor slabs

对已竣工半年至 2年的 1 3项现浇钢筋砼住宅工程进行调查 ,楼板出现裂缝的有 9项 ,主要发生在房屋外墙房间楼板的转角处 ,少数在板跨中部 .其成因一是环境温度变化和砼本身的收缩变形引起 ;二是泵送砼配合比的改变造成砼的收缩值增大 ;三是采用Φ6的钢筋太软等引起 .针对这些问题提出了相应的设计和施工措施 ,以防止和避免此类问题的发生 .

Based on an investigating 9 out of 13 dwelling are found with cracks on the floor slabs esp.on the corner formed by two outward walls and a few on the middle span of the floor slabs.The cracks are caused by three chief factors:the first is the change of the ambient humidity and the deformed of the concrete itself;the second is the concrete pouring by pumps has changed the concrete mixture rate and increased the contracted rate of concrete;the third is the Φ6 steel bar is too soft to resist the negative moment.For preventing the cracks on the floor slabs,some precautions in the design and construction are presented.