加速老化对纤维网格布增强水泥基材料弯曲性能的影响

Effect of Accelerated Aging on Flexural Properties of Glass Fiber Mesh Reinforced Cement

为研究玻璃纤维增强砂浆(GRC)的长期耐碱性,对无网格布(NC)增强的试件、中碱玻璃纤维(CNP)网格布增强试件、低锆玻璃纤维网格布(ARNP)增强试件和高锆玻璃纤维网格布(ARNPH)增强试件分别进行了加速老化试验、弯曲试验和扫描电镜试验。试验结果表明:网格布对GRC试件的开裂抗弯强度影响较小;随着裂缝扩展,GRC试件在加载过程中出现挠度硬化现象并伴随多条裂缝,玻璃纤维可显著提高GRC试件承载能力;经过加速老化后,玻纤因受到腐蚀,对GRC试件的增强作用随着ZrO_2含量减小而减小;中碱玻璃纤维腐蚀后表面出现层状剥落且纤维有效直径减小,受腐蚀程度较深,低锆玻璃纤维在腐蚀后表面出现点状突起,未见层状剥落,高锆玻璃纤维在腐蚀后表面未见明显变化。

Accelerated aging experiment, flexural experiment and electron microscope scanning were conducted to investigate the long-term alkali resistance of GRC specimen reinforced by CNP, ARNP and ARNPH glass fiber mesh. The result shows that glass fiber mesh has little effect on flexural strength at cracking. The GRC specimen shows deflection hardening with multi-cracking during loading process. Bearing capacity of specimen can significantly increase with fiber mesh reinforcement. After accelerated aging, the strengthening effect decreases with the decreasing of ZrO2 content in glass fiber which can be corroded by alkali. Shells were formed around corroded CNP glass fiber filament and were peeled off, with diameter of filament decreased. It indicated that CNP glass fiber was severely corroded. Pitting corrosion other than shells formation were found on the surface of corroded ARNP glass fiber. There was no obvious change on the surface of corroded ARNPH glass fiber.