再生混凝土体积稳定性与抗裂性能研究

The recycled coarse and fine aggregate with different sources and age are used to make recycled concrete, and the systematic experimental study and mechanism analysis are carried out. The strengthening pretreatment experiment of recycled coarse aggregate and meso-structure test of recycled concrete are carried out to reveale the effect regularity and its mechanism on the slump loss, porosity and mechanical properties. And then the recycled coarse aggregate pretreatment method to effective improve its performance is proposed, concluding pre-wet methods and a variety of paste wrapped stone methods. Through the recycled aggregate concrete volume stability test, the effect regularity and its mechanism of factors on the autogenous shrinkage, drying shrinkage and creep is revealed. In the results, the comparability of test data should be obtained. And then, the mix design method of recycled aggregate concrete to improve its volume stability is proposed, and the calculation model of autogenous shrinkage, drying shrinkage and creep of recycled aggregate concrete is established. Through the experiments of the cracking behaviors of recycled aggregate concrete, the effect regularity of raw materials and environmental conditions on the cracking behaviors of recycled aggregate concrete is revealed, and the effective way to improve the recycled concrete cracking performance is presented. The project is important to solve the key technology of recycled aggregate concrete and to ensure the durability of recycled aggregate concrete structure.

采用不同来源、不同龄期的再生粗骨料、细骨料配制再生混凝土，针对再生混凝土的材料特点开展系统、深入的试验研究和机理分析。通过再生粗骨料强化预处理方法试验和再生混凝土细观结构试验，揭示再生粗骨料预湿法和各种净浆裹石法对再生混凝土的坍落度损失、孔隙率以及基本力学性能的影响规律及其机理，提出有效改善再生粗骨料性能的方法。通过再生混凝土体积稳定性试验研究，揭示其自生收缩、干燥收缩和徐变受各因素影响的规律及其机理，试验成果要克服目前试验数据可比性差的问题，提出有效提高再生混凝土体积稳定性的配合比设计方法，建立符合再生混凝土特性的自生收缩、干燥收缩和徐变计算模型。通过再生混凝土的抗裂性能试验研究，揭示再生混凝土抗裂性能受原材料与配合比、环境条件等的影响规律，提出提高再生混凝土抗裂性能的有效方法。本项目研究对解决再生混凝土工程应用的关键技术，确保再生混凝土结构的耐久性具有重要意义。

采用不同来源、不同龄期的再生粗骨料、细骨料配制再生混凝土，针对再生混凝土的材料特点开展系统、深入的试验研究和机理分析。通过再生粗骨料强化预处理方法试验和再生混凝土细观结构试验，揭示再生粗骨料预湿法和各种净浆裹石法对再生混凝土的多重界面过渡区细微观结构、坍落度损失、基本力学性能的影响规律及其机理，提出有效改善再生粗骨料性能的方法。通过再生混凝土体积稳定性试验研究，揭示其自生收缩、干燥收缩和徐变受再生骨料取代率、矿物掺合料掺量、水胶比等因素的影响规律及其机理，提出有效提高再生混凝土体积稳定性的配合比设计方法，建立符合再生混凝土特性的自生收缩、干燥收缩和徐变计算模型。通过再生混凝土楔入劈拉断裂试验以及双K断裂参数的计算，对再生混凝土的抗裂性能进行研究，揭示再生混凝土抗裂性能受原材料与配合比等因素的影响规律，提出改善再生混凝土抗裂性能的有效方法。本项目研究对解决再生混凝土工程应用的关键技术，确保再生混凝土结构的耐久性具有重要意义。