Department of Civil Engineering, Ghulam Ishaq Khan Institute of Engineering Sciences and Technology, Topi, Pakistan.
Shanghai Key Laboratory for Digital Maintenance of Buildings and Infrastructure, School of Naval Architecture, Ocean and Civil Engineering, Shanghai Jiao Tong University, Shanghai, China.
PLoS One. 2024 Jul 15;19(7):e0305143. doi: 10.1371/journal.pone.0305143. eCollection 2024.
Concrete structures are susceptible to cracking, which can compromise their integrity and durability. Repairing them with ordinary Portland cement (OPC) paste causes shrinkage cracks to appear in the repaired surface. Alkali-activated binders offer a promising solution for repairing such cracks. This study aims to develop an alkali-activated paste (AAP) and investigate its effectiveness in repairing concrete cracks. AAPs, featuring varying percentages (0.5%, 0.75%, 1%, 1.25%, 1.5%, and 1.75%) of polyethylene (PE) fibers, are found to exhibit characteristics such as strain hardening, multiple plane cracking in tension and flexure tests, and stress-strain softening in compression tests. AAP without PE fibers experienced catastrophic failure in tension and flexure, preventing the determination of its stress-strain relationship. Notably, AAPs with 1.25% PE fibers demonstrated the highest tensile and flexural strength, exceeding that of 0.5% PE fiber reinforced AAP by 100% in tension and 70% in flexure. While 1% PE fibers resulted in the highest compressive strength, surpassing AAP without fibers by 17%. To evaluate the repair performance of AAP, OPC cubes were cast with pre-formed cracks. These cracks were induced by placing steel plates during casting and were designed to be full and half-length with widths of 1.5 mm and 3 mm. AAP both with and without PE fibers led to a substantial improvement in compressive strength, reducing the initial strength loss of 30%-50% before repair to a diminished range of 2%-20% post-repair. The impact of PE fiber content on the compressive strength of repaired OPC cube is marginal, providing more flexibility in using AAP with any fiber percentage while still achieving effective concrete crack repair. Considering economic and environmental factors, along with observed mechanical enhancements, AAPs show promising potential for widespread use in concrete repair and related applications, contributing valuable insights to the field of sustainable construction materials.
混凝土结构容易出现裂缝，这会影响其完整性和耐久性。使用普通硅酸盐水泥 (OPC) 浆体修复它们会导致修复表面出现收缩裂缝。碱激活粘结剂为修复此类裂缝提供了一种有前途的解决方案。本研究旨在开发一种碱激活浆体 (AAP) 并研究其修复混凝土裂缝的效果。发现具有不同百分比 (0.5%、0.75%、1%、1.25%、1.5% 和 1.75%) 的聚乙烯 (PE) 纤维的 AAP 具有应变硬化、在拉伸和弯曲试验中出现多平面裂缝以及在压缩试验中表现出应力-应变软化等特征。没有 PE 纤维的 AAP 在拉伸和弯曲试验中发生灾难性破坏，阻止了其应力-应变关系的确定。值得注意的是，含有 1.25%PE 纤维的 AAP 表现出最高的拉伸和弯曲强度，在拉伸中比 0.5%PE 纤维增强 AAP 高 100%，在弯曲中高 70%。而 1%PE 纤维导致最高的抗压强度，比没有纤维的 AAP 高 17%。为了评估 AAP 的修复性能，用预制裂缝浇注 OPC 立方体。这些裂缝是在浇注时放置钢板引起的，设计为全长和半长，宽度分别为 1.5 毫米和 3 毫米。含有和不含有 PE 纤维的 AAP 都导致抗压强度显著提高，将修复前初始强度损失 30%-50%降低到修复后 2%-20%的范围。PE 纤维含量对修复后 OPC 立方体抗压强度的影响较小，在使用任何纤维百分比的 AAP 时提供更大的灵活性，同时仍能有效修复混凝土裂缝。考虑到经济和环境因素以及观察到的机械增强效果，AAP 显示出在混凝土修复和相关应用中广泛使用的潜力，为可持续建筑材料领域提供了有价值的见解。
