蒸汽养护混凝土变形行为及开裂风险评估

Deformation Behavior and Cracking Risk Assessment of Steam-cured Concrete

通过超声波法、劈裂抗拉试验、水化热试验以及收缩-温湿度一体化试验分别研究了蒸汽养护混凝土弹性模量、抗拉强度、水化规律以及收缩变形-温湿度变化规律。结果表明:蒸汽养护增大了混凝土的弹性模量与抗拉强度;高温提高了水泥净浆的水化速率与水化程度,蒸汽养护水泥净浆水化模型被成功建立;蒸养至拆模阶段,混凝土呈现“膨胀-收缩”的变化规律;拆模之后,蒸汽养护混凝土的变形以干燥收缩为主,建立的复掺粉煤灰与矿粉蒸汽养护混凝土拆模后的自收缩与总收缩一体化模型的计算值与试验数据吻合较好;建立的密封条件下拆模后蒸汽养护混凝土开裂评价模型可用于蒸汽养护混凝土开裂性定量评价。

Through the ultrasonic method,split tensile test,the heat of hydration test and integrated shrinkage-temperature-relative humidity test,elastic modulus,tensile strength,hydration and shrinkage deformation-temperature-relative humidity were studied.Results indicated that steam curing increased the elastic modulus and tensile strength of concrete.High temperature promoted the hydration rate and hydration degree of cement paste.A steam-cured cement paste hydration model was proposed.From steam curing to demoulding stage,the concrete presented an‘expansion-shrinkage’change law.However,the deformation of steam-cured concrete dominated by drying shrinkage after demoulding.An integrated model of auto-shrinkage and total shrinkage of steam-cured concrete mixed with fly ash and slag after demoulding was proposed.The calculated values of this model are in good agreement with the experimental data.Finally,a cracking evaluation model for steam-cured concrete after demoulding under sealed conditions was proposed.It can be used for quantitative evaluation of crack formation of steam-cured concrete.