3D打印纤维微筋增强地聚合物宏细观力学性能研究

3D concrete printing gain rapidly development in the field of civil engineering and construction, with various advantages such as mouldless, rapidness and high flexibility. Geopolymer belongs to a kind of environmental protection and low-carbon concrete material, which has excellent mechanical and durable properties. The characteristics of the early strength is particularly suitable for 3D printing process. However, 3D printing is a kind of unreinforced construction process, and the printed structures perform relatively low carrying capacity. This study firstly develop 3D printable geopolymer materials, analyze the coordination between the work performance and printing process, and establish a quantitative assessment method for the manufacturing of 3D printable geopolymer; In particular, to improve and enhance the 3D printed geopolymer, this study propose an innovative reinforcement method to synchronously distribute fiber micro-reinforcement into the deposited materials, investigate the bonding and enhance performance between the interface of fiber micro-reinforcement and matrix. Employing microstructure detection method to reveal the influencing mechanism of the weak interfaces between adjacent print layers to the macroscale mechanical behavior, and to probe the influence of fiber micro-reinforcement to the macro/mesoscopic mechanical characteristics and deformation failure mechanism of geopolymer; At last, establish topology optimization and path planning method for 3D printing structures, aiming to realize the lightweight of 3D printed geopolymer structure under the condition of sufficient mechanical bearing performance. This study provides an effective and promising solution for the reinforcement of 3D printing geopolymer and provide experimental basis and theoretical references for the brittle modification and mechanical enhancement of 3D printing geopolymer.

混凝土3D打印凭借其无模化、快速化、灵活化的优势在土木建筑领域发展迅速。地聚合物是一种环保低碳的混凝土材料，具有优异的力学和耐久性能，其速凝早强的特性适用于3D打印工艺。然而，3D打印是一种无筋建造工艺，打印结构的力学承载能力较弱。本项目研制可3D打印的地聚合物材料，分析工作性能与打印工艺的协调性，建立3D可打印性能的量化评估方法；研发纤维微筋增强3D打印地聚合物的同步布筋方法，研究不同微筋与地聚合物基体的界面粘结和增强性能，实现3D打印材料的增强增韧；应用微观探测分析手段，揭示相邻打印层细观界面对地聚合物力学行为的影响机制，研究纤维微筋增强地聚合物的宏细观力学性能与变形破坏机理；建立3D打印结构结合拓扑优化与路径规划方法，在满足力学承载性能的条件下，实现地聚物加筋结构的轻量化。本研究提供一种有效的3D打印地聚合物的同步加筋方案，为地聚物的脆性改性与承载性能的改善提供实验基础和理论依据。

混凝土3D打印凭借其无模化、快速化、灵活化的优势在土木建筑领域发展迅速。本项目旨在研发3D打印低碳利废材料，解决3D打印混凝土材料的脆性特征，研发同步加筋增韧方法来改善和提高3D打印材料的抗变形能力。项目组经过三年的研究，研制了3D打印地聚物材料，解决了地聚物速凝与挤出打印工艺协调性差的难题，明确了3D可打印性的量化评估参数指标体系，建立了拌合物性能和打印工艺参数的优化设计方法，实现了地聚物等低碳利废材料连续稳定打印成型。深入分析了3D打印混凝土宏细观的力学性能，用超声、智能压电技术，量化分析了3D打印混凝土的非均质性以及在不同应力水平下的损伤累计特征；提出了聚合物改性砂浆增强和内养护界面增强方法，提高了界面的密实度和力学强度。研发了适用于挤出型打印的连续纤维同步置入方法，实现了纤维筋的置入与地聚物材料的挤出过程的适应和协调；提出了层间界面U型钉增韧方法，显著提高了界面的强度和韧性；实现了3D打印混凝土水平和垂直两个方向的同步加筋增韧，具有高度的灵活性。研究了3D打印轻量化结构的变形破坏特征与承载性能，揭示了3D打印结构的破坏机理；提出了3D打印结构的自锁连接方法，借助DIC技术分析了接触界面在复合受力状态下的力学行为与破坏机理。本项目从材料的制备与性能调控，力学行为的宏细观量化表征，到3D打印轻量化结构的承载性能与破坏机理，进行了较为系统的研究，对3D打印技术的发展和推广具有重要的推动作用。