基于原位试验的超长薄板早期防裂施工措施.pdf

施工技术 2010年7月 108 CONSTRUCTION TECHNOLOGY 第39卷第7期 基于原位试验的超长薄板早期防裂施工措施 张希黔，康明，华建民，袁渊 (重庆大学土木工程学院，重庆400045) [摘要]通过现场原位试验，直观反映了超长薄板构件早期内部水化度及混凝土应变的变化，对主要施工工况 (拆模、水养护)对超长薄板构件内力的影响实现了定量评价.试验结果表明，混凝土水化降温影响集中在混凝 土浇筑后的0.5-3d 此时混凝土拉应变增长迅速，薄板早期开裂风险极大；拆模可以降低混凝土拉应变水平约 31%:洒水养护可在高温干燥条件下降低混凝土拉应变水平37%，持效时间9-12，防裂效果显著.工程中成功的 早期防裂控制施工措施包括防裂控制意识及措施的提前，适时拆模及动态养护. [关键词]超长薄板；早期裂缝；原位试验；施工防裂措施；拆模；动态养护 [中图分类号]TU755.7 [文献标识码]A [文章编号]1002-8498(2010)07-0108-03 Research on Construction Precautions of Early-age Shrinkage Cracks in Super-long Slab on Basis of On-site Experiment Zhang Xiqian Kang Ming Hua Jianmin Yuan Yuan (College of Civil Engineering Chongqing Unisersity Chongging 400045 China) Abstract:Based on on-site experiment about super-long slab the development laws of the intermal hydration temperature and concrete strain in the slab are in detail described and the influence of construction including removing mould-boards and curing are quantificationaly evaluated.In the results of on-site experiment decreasing of hydration temperature in 0.5 to 3 days after concrete placed causes that concrete strain in the slab rapidly grows up so the risk of early-age shrinkage cracks is increasing. However concrete strain are reduced by 31%for removing molding-boards and 37%for curing which continues for 9 to 12 hours in the hot climate.The effects of preventing early-age shrinkage cracks in the super-long slab are famous because of the special construction provisions being taken. Key words:super-long slab;ear...