内养护补偿收缩混凝土的抗裂性能

Crack Resistance of Internal Curing Shrinkage Compensating Concrete

关键词:  内养护  膨胀剂  补偿收缩  塑性收缩  抗裂性

Key words:  internal curing  expansive agent  shrinkage compensation  plastic shrinkage  crack resistance

摘要:

研究了UEA（硫铝酸钙类膨胀剂）和HCSA（硫铝酸钙氧化钙类膨胀剂）的膨胀特征，比选出适宜于配制补偿收缩混凝土的膨胀剂；研究了内养护对补偿收缩混凝土抗压强度、早期变形、干缩落差和抗裂性的影响，并在西北大风干旱地区开展了内养护补偿收缩混凝土的现场应用试验.结果表明：HCSA的膨胀效能高、膨胀速率快、对后期水分补充的依赖程度低，掺量（质量分数）为6%时可满足混凝土补偿收缩的要求；内养护可提高HCSA的膨胀效能，减小补偿收缩混凝土的塑性收缩和干缩落差，提高补偿收缩混凝土的抗裂性；内养护补偿收缩混凝土用于西北大风干旱地区暴露面大的薄壁平板实体结构时具有良好的抗裂性.

Abstract:

The expansive characteristics of UEA(calcium sulphoaluminate expansive agent) and HCSA(calcium sulphoaluminate calcium oxide expansive agent) were studied, and then the expansive agent suitable for shrinkage compensating concrete was determined.The influences of internal curing on compressive strength, early deformation, drying shrinkage drop and crack resistance of shrinkage compensating concrete were investigated in laboratory, and subsequent field application was carried out in northwest high wind arid area. It is indicated from the result that HCSA with higher expansion and less dependence on external water curing at later stage can meet the shrinkage compensating requirement of concrete as long as its use level(by mass) reaches up to 6%; with internal curing, the effectiveness of HCSA could be improved, and the plastic shrinkage and drying shrinkage drop of shrinkage compensating concrete could be reduced, and the crack resistance of shrinkage compensating concrete could be improved; the internal curing shrinkage compensating concrete applied in thin plate structure with vast exposed surface in northwest high wind arid area exhibits good crack resistance.