基于CPM模型的生态自密实混凝土材料设计关键技术研究

Self-Consolidating Concrete (SCC) is worldwide used due to its excellent mechanical and durability properties as well as its ability to produce a green construction product that is cost effective. However, the higher binder content required in the mix proportioning of SCC can lead to higher CO2 emission. The design of ecological SCC (Eco-SCC) is the major development direction of high-performance cement-based composite materials. Based on the investigation of complex packing mechanism of multiple size classes micro-particles, the modified Compressible Packing Model (CPM), including the influences of interaction effects of micro-particles and compaction effects of multi particles system due to inter-particle forces will be established. The modified CPM with high precision can be used for multiple size classes packing calculation. Moreover, based on the study of physical-, chemical-packing and the combined effects of multiple size classes micro-particles, the mathematical results from modified CPM can be used to establish a mix design protocol for Eco-SCC. Furthermore, based on the investigation of rheological properties of CPM-based Eco-SCC, as well as the study of strength-impermeability double performance index-based materials design technologies, the relationships between strength, durability, and activities of cementitious materials can then be established, and the long-term strength and impermeability can be predicted given short-term testing protocol. Based on the proposed investigation, the design principles and key technologies of designing low cement content, ecological self-consolidating cement-based composite materials can be established. The research project has novel theoretical value and practical implication, and will contribute to enhancing design specifications.

自密实混凝土因其绿色施工和良好的力学、耐久性能，在世界范围内广泛使用。但其较高胶凝材料用量导致较高碳排放。低胶凝材料含量生态自密实混凝土（Eco-SCC）设计与制备是高性能水泥基复合材料领域重要研究及发展方向。本项目基于对多元微粉体系颗粒堆积复杂机理问题的研究，建立考虑颗粒间相互作用效应和微粉体系压实效应的高适应性、高精度CPM（可压缩堆积）修正模型；在阐述多元粉体颗粒体系中物理、化学密实效应基础上，将修正模型数学解析与材料设计相结合；同时，在研究基于CPM的Eco-SCC流变性能的前提下，针对基于强度及抗渗性双指标的材料设计方法进行研究，建立胶凝材料活性与强度、抗渗性关联模型，利用模型在早期对Eco-SCC长期强度和抗渗性进行准确预测。基于上述研究，形成低胶凝材料生态自密实水泥基复合材料设计理论及关键技术。研究具有广泛的理论价值及巨大的工程实用性，对于SCC设计规范修订具有重要学术价值。

项目基于可压缩堆积（CPM）模型，研究了低胶凝生态自密实水泥基复合材料的设计理论及关键技术，主要研究成果包括：1）分析了多元微粉材料复合堆积效应，提出了用水量富余指数W和水泥颗粒间隙指数BSF，分析骨料和胶凝材料堆积对水泥基材料相关性能的影响，并基于多元微粉材料的复合堆积效应评价指标建立了水泥基材料工作性能和力学性能预测模型，模型预测3d、7d和28d力学性能误差分别为14.52%、9.04%和2.92%；2）利用数值模拟对具有离散特点的多元微粉颗粒进行相互作用及压实作用的仿真模拟，提出了多元微粉相互作用力，修正了多元微粉颗粒堆积模型，CPM修正模型颗粒堆积密实度的模拟计算结果平均误差仅为2.1%；3）考虑骨料颗粒形貌特性，结合数值回归分析方法，提出了与骨料颗粒形貌特性相关的形貌函数，对CPM模型中的作用效应系数进行优化和完善，使颗粒堆积密实度的预测值与实际值更加接近；4）分析了不同堆积密实度下水泥基材料的孔隙率、弹性模量和水化程度，研究了水泥基材料相互堆积的物理、化学效应，基于效应机理指导了混凝土配合比设计；5）采用内掺法和外掺法两种实验方法相结合，通过粉煤灰活性与粉煤灰/水泥用量的比值关系建立强度与氯离子渗透性的关联方程，设计了以混凝土强度和抗渗性为最终指标、以掺合料活性为中间变量的水泥基材料双指标设计方法；6）基于CPM修正模型及相关理论研究，形成了低胶凝材料含量生态自密实水泥基复合材料设计理论及关键技术。