纤维及复合粉体增强混凝土轴拉性能试验研究

Experimental Study on Tensile Performance of Fiber and Composite Powder Reinforced Concrete

摘要: 为解决现代超高层建筑及大跨度桥梁结构对混凝土强度与韧性的更高需求，本研究聚焦纤维及复合粉体增强混凝土的轴心抗拉性能，通过在混凝土基体中掺入聚乙烯醇、聚丙烯腈(PAN)纤维及复合粉体，采用控制变量法设计11组不同配合比的混凝土试件开展轴心抗拉试验。试验采用哑铃式试件，以E45.305型MTS电液伺服万能试验机按0.2 mm/min位移控制加载，同步采集应力–应变全曲线数据，分析纤维掺量、纤维种类及双掺复合粉体对混凝土抗拉强度、极限应变及破坏形态的影响，并构建抗拉强度模型。结果表明：纤维与复合粉体的掺入可显著提升混凝土抗拉强度与极限应变。其中，宝华林PVA纤维掺量1.2 kg/m³时，混凝土抗拉强度较素混凝土(P₀)提升107.27%；在此基础上额外掺入0.4 kg/m³复合粉体，抗拉强度进一步提升19.55%，极限应变更是大幅提升165.63%，且应力–应变曲线呈现平缓的应变硬化阶段。从破坏形态看，素混凝土为脆性断裂，而纤维增强混凝土断裂面更整齐、断裂声音较小，纤维的桥接作用有效增强了水泥胶与纤维的粘结能力，改善了混凝土韧性。此外，掺入复合粉体的混凝土试件试验数据变异系数更低，测试结果稳定性更优。综合来看，宝华林生产的1.2 kg/m³ PVA纤维与0.4 kg/m³复合粉体的组合，对混凝土轴拉性能的增强效果最佳，可为工程中混凝土材料的优化应用提供参考。

Abstract: To address the heightened demands for concrete strength and toughness in modern super-tall buildings and large-span bridge structures, this study investigates the axial tensile performance of fiber-reinforced and composite powder-enhanced concrete. By incorporating polyvinyl alcohol (PVA), polyacrylonitrile (PAN) fibers, and composite powders into the concrete matrix, 11 test specimens with varying mix proportions were designed using a controlled variable method. Dumbbell specimens were tested using an E45.305 MTS electro-hydraulic servo universal testing machine, with displacement-controlled loading at 0.2 mm/min while simultaneously collecting full stress-strain curve data. The research analyzes the effects of fiber content, fiber type, and dual-composite powder incorporation on tensile strength, ultimate strain, and fracture morphology, ultimately establishing a tensile strength model. Results demonstrate that fiber and composite powder additions significantly enhance concrete’s tensile strength and ultimate strain. Specifically, when Baohualin PVA fibers were added at 1.2 kg/m³, the tensile strength increased by 107.27% compared to plain concrete (P₀). Subsequent addition of 0.4 kg/m³ composite powder further boosted tensile strength by 19.55% and dramatically increased ultimate strain by 165.63%, with the stress-strain curve exhibiting a gradual strain hardening phase. Fracture morphology analysis revealed that plain concrete exhibited brittle fracture, while fiber-reinforced concrete displayed more uniform fracture surfaces and quieter fracture sounds. The bridging effect of fibers effectively improved the bond between cement paste and fibers, enhancing concrete toughness. Additionally, concrete specimens incorporating composite powders demonstrated lower coefficient of variation in test data, indicating superior measurement stability. In general, the combination of 1.2 kg/m³ PVA fiber and 0.4 kg/m³ composite powder produced by Baohua Lin has the best effect on the enhancement of concrete axial tensile performance, which can provide a reference for the optimal application of concrete materials in engineering.