蒸养混凝土早期断裂性能研究

Experimental study on early fracture properties of steam-cured concrete

为研究蒸养混凝土早期的断裂性能,开展了养护时间为4,8,16,24和48 h的混凝土三点弯曲梁断裂试验,分析了不同养护时间下蒸养混凝土的断裂性能和力学性能,进而给出了蒸养混凝土早期断裂参数与成熟度的关系。基于数字图像相关方法,测得了混凝土试件表面的全场位移及应变信息,研究了裂缝扩展的断裂演化过程。结果表明:在60℃蒸汽养护条件下,当养护时间在24 h内时,蒸养混凝土的力学性能随养护时间逐渐增大,养护时间超过24 h,蒸养混凝土的力学性能呈下降趋势;蒸养混凝土断裂性能在养护4-8 h内迅速提高,超过8 h后,混凝土断裂性能提升缓慢;其早期断裂韧度与成熟度具有较好的相关关系。

To study the early fracture properties of steam-cured concrete, three-point bending(TPB) specimens at different curing time(4 h, 8 h, 16 h, 24 h and 48 h) were tested, and the effects of the curing time on the mechanical and fracture properties of the steam-cured concrete were analyzed. Then, the relationship between fracture parameters and maturity was developed. Based on the digital image correlation(DIC) method, the full-field displacement and strain information of crack propagation were measured, and the damage evolution process of crack propagation was studied.The results indicate that the mechanical properties of steam-cured concrete increase with the curing time in 24 hours followed by a decrease tendency when the curing time is beyond 24 h. The fracture properties of steam-cured concrete increase significantly within 4-8 h of curing time and then rise slowly after 8 h. A good correlation between the fracture toughness and the maturity was observed to provide a basis for the fracture parameters of steam-cured concrete.