长寿命海工高性能混凝土的研究与应用

Research and Engineering Application of Long Life Marine High Performance Concrete

通过优化不同胶凝材料的用量及比例,提出了黄海二桥工程C45承台结构的混凝土配合比,并采用菲克第二定律对腐蚀环境作用等级最高的该结构进行寿命评估。结果表明:随着硅灰掺量的增大,混凝土抗压强度有较大提高,28 d强度最高可达68.7 MPa, 56 d氯离子扩散系数为1.6×10^(-12) m^(2)/s,抗裂性能可达到L~Ⅳ等级;且降低了混凝土水化放热量,从而控制开裂风险;氯盐侵蚀作用下结构钢筋表面氯离子达到临界浓度的时间与附件措施保护年限的总和均超过100年,满足耐久性要求。

By optimizing the dosage and proportion of different cementitious materials,the concrete mix proportion of C45 bearing platform structure of the second yellow sea bridge was put forward,and Fick’s second law was used to evaluate the service life of the structure with the highest action level of corrosive environment.The results showed that with the increase of silica fume content,the compressive strength of concrete was greatly improved,the maximum strength in 28 days was 68.7 MPa,and the chloride ion diffusion coefficient in 56 days was 1.6×10^(-12)m^(2)/s,and the crack resistance could reach L~Ⅳgrade.And the heat release of concrete hydration was reduced,so as to control the risk of cracking.Under the action of chloride salt erosion,the sum of the time when the chloride ion on the surface of structural reinforcement reaches the critical concentration and the protection period of accessory measures exceeds 100 years,meeting the durability requirements.