混凝土早龄期抗裂性能综合优化与试验评价

早龄期开裂是影响混凝土长期性能的重要缺陷,必须严格控制。从原材料选用和配合比优化的角度,就改善混凝土的早龄期抗裂性能提出了一系列技术措施,并对这些措施的有效性分别进行了基于自由和约束收缩试验的评价。结果表明,减缩剂具有减小自由收缩应变和推迟约束开裂龄期的作用;以粉煤灰部分取代硅酸盐水泥会导致早期开裂龄期提前;抗拉性能较高且自由收缩减小的混凝土可望获得较好的早龄期抗裂性能。

Optimization of early-age cracking resistance of concrete and its experimental investigations

Early-age cracking of concrete is an utmost drawback of deteriorating its long-term performance. In this paper,a serial of measures in terms of materials selection and mixture proportions optimization was employed to improve early-age cracking resistance of concrete. Moreover,the efficiency of these technical measures was evaluated with free and restrained shrinkage tests,respectively. Results show that the shrinkage reducing agent has the effect of reducing the free shrinkage strain and delaying the constraint cracking age. The partial replacement of Portland cement by fly ash leads to an earlier cracking age. The mixtures with high tensile strength and low free shrinkage strain is anticipated to obtain relatively good early-age cracking resistance.