荷载与海洋环境耦合作用下再生混凝土中钢筋锈蚀及构件受力性能研究

The multiple interfaces and large porosity of recycled aggregate concrete are obviously different from common concrete. By means of electrochemical synthesis instrument and environmental electron microscope scanner, the mechanism of reinforcement corrosion in recycled aggregate concrete under simultaneous action of load and chloride will be thoroughly investigated. Different factors such as pretreatment methods to recycled coarse aggregate, recycled coarse aggregate replacement ratio and mineral admixtures are involved for studying the corresponding effects on the corrosion potential and the corrosion current density of reinforcement, performance of the interface between the concrete and reinforcement, and the cracking time of concrete cover of recycled concrete. Then the mix design method for recycled aggregate concrete with high chloride critical value and excellent pretreatment methods to recycled coarse aggregate is obtained. Base on this, the mechanical performance experiments of the recycled aggregate concrete beams and columns under dry-wet circulation of chloride and the environment of carbonation will be conducted in the stepping multi-function marine environment laboratory that simulates the real natural marine environment. The influences of reinforcement corrosion under sustained load on the mechanical behavior of recycled aggregate concrete components and the effects of transverse cracks on the chloride ion erosion, corrosion current density and corrosion ratio can be revealed. Therefore, the formulas to predict the ductility, stiffness, bearing capability of recycled aggregate concrete components under the dry-wet alternate action in the marine environment are proposed. At the same time, energy dissipation experiment of the corroded reinforced recycled aggregate concrete beams and columns under cyclic loading will be carried on by electric accelerated corrosion method. The influence of reinforcement corrosion rate on hysteretic curves, skeleton curves and stiffness degradation curves of recycled aggregate concrete components will be revealed.

针对再生混凝土细观多重界面及孔隙率较大等特点，以再生粗骨料预处理方法及其取代率和矿物掺合料等为主要因素，采用电化学综合测试仪及环境电镜扫描仪，深入研究荷载与氯盐耦合作用下再生混凝土中钢筋锈蚀机理，揭示各因素对钢筋腐蚀电位、腐蚀电流密度、混凝土与钢筋界面状况的影响规律和机理，提出具有高抗锈蚀能力的再生混凝土配合比设计方法和再生粗骨料预处理方法。在此基础上，采用步入式多功能海洋环境模拟试验箱模拟自然海洋环境，进行氯盐干湿循环和碳化环境下再生混凝土配筋梁、柱的受力性能试验，揭示持续荷载下钢筋锈蚀对构件受力性能影响规律，和横向裂缝对氯离子侵蚀量、腐蚀电流密度及锈蚀率等影响规律，建立海洋环境中干湿交替作用下再生混凝土构件的延性、刚度和承载力计算方法。同时采用电加速锈蚀法，进行锈蚀钢筋再生混凝土梁、柱在反复荷载下的耗能性试验，研究钢筋锈蚀率等对再生混凝土构件滞回曲线、骨架曲线、刚度退化曲线的影响规律。

我国每年产生废弃混凝土等建筑垃圾超过15亿吨，同时消耗混凝土超过40亿立方米。有效利用废弃混凝土、推广再生混凝土是解决环境污染和生态危机、减少开山采石节约自然资源的迫切需要。然而由于再生骨料表面附着老砂浆，加剧了混凝土材料固有的薄弱环节，使再生混凝土的氯离子侵蚀、钢筋锈蚀及配筋结构受力性能等与普通混凝土有重大差别，影响海洋环境下再生混凝土结构的耐久性与安全性。.本项目通过荷载与海洋环境耦合作用下再生混凝土中钢筋加速锈蚀试验、再生混凝土配筋梁、柱等构件的受力性能试验，结合理论分析和数值模拟，开展荷载与海洋环境耦合作用下再生混凝土中钢筋锈蚀及构件受力性能研究，主要研究内容与结果包括：.进行钢筋加速锈蚀试验，以再生粗骨料预处理方法及其取代率和矿物掺合料掺量等为主要因素，采用电化学综合测试仪，得到各因素对钢筋腐蚀电位、腐蚀电流密度的影响规律，揭示再生混凝土梁、柱构件在荷载与海洋环境耦合作用下的钢筋锈蚀性能特点，提出具有高抗锈蚀能力的再生混凝土配合比设计方法。.进行荷载与海洋环境下再生混凝土配筋梁、柱的受力性能试验，揭示持续荷载下钢筋锈蚀对再生混凝土梁、柱构件受力性能影响规律。以此为基础，研究各因素对再生混凝土配筋梁、柱中构件挠度、混凝土极限压应变、构件延性和极限承载力等的影响规律，提出改善持续荷载下配筋再生混凝土构件受力性能有效方法。.进行低周反复荷载作用下锈蚀钢筋再生混凝土框架节点抗震性能试验研究，开展荷载与环境耦合作用下锈蚀钢筋再生混凝土框架边节点抗剪性能数值分析，对不同锈蚀率、不同混凝土强度和不同配箍率下再生混凝土框架边节点抗剪承载力进行数值模拟，分析各因素对再生混凝土框架边节点滞回曲线、骨架曲线、累计耗能、变形性能、刚度退化等抗震性能的影响规律，建立再生混凝土框架边节点的抗剪承载力模型。.研究结果为沿海地区再生骨料混凝土结构设计及推广应用提供依据。