高性能玻璃纤维增强氯氧镁水泥的加速寿命试验与微观机理

利用SIC( strand in cement)试验方法,测定了玻璃纤维增强氯氧镁水泥(glass fiber reinforced magnesium oxychloride cement,GRMC)板材在80℃热水加速老化试验条件下的弯曲强度变化,研究了其加速试验寿命,并运用XRD、DSC -TG、FT-IR和SEM分析其水化产物组成和微观结构形貌,观察了玻璃纤维在氯氧镁水泥基体中的腐蚀特征.结果表明:未添加任何改性剂的普通GRMC在80℃热水加速老化2.5d后,其主要水化产物5·1 ·8大量分解,物相以叶片状的Mg( OH)2为主,促使玻璃纤维被基体腐蚀,导致力学性能急剧下降,预期使用寿命不超过4y.掺加复合抗水外加剂和矿渣的高性能GRMC由于5·1 ·8相的稳定存在和玻璃纤维不被腐蚀,在加速老化试验条件下的强度保留率高达60％以上,预期使用寿命超过了50 y.因此,5·1 ·8的稳定存在是保证高性能GRMC的玻璃纤维稳定性和长期耐久性的重要基础.

Acceleration Life Test and Microscopic Mechanism of High Performance Glass Fiber Reinforced Magnesium Oxychloride Cement

Bending strength change of glass fiber reinforced magnesium oxychloride cement(GRMC) board at 80 ℃ hot water accelerated aging was tested by the strand-in-cement(SIC) method.Hydration product component,microscopic structure and corrosion feature of glass fibers in the oxychloride magnesium cement matrix were observed by XRD,DSC-TG,FT-IR and SEM.The results showed that its main hydration product 5·1·8 was hydrolysed and Mg(OH)2 became the main phase for common GRMC board after accelerated aging 2.5 d at 80 ℃ hot water which led to the corrosion of glass fiber caused by matrix and rapid degradation of mechanical property,so the expected service life was not more than 4 years.For high performance GRMC board doped with compound water-repellent admixtures and slag,strength retention was higher than 60% at accelerated aging state because of the stability of 5·1·8 and noncorrision of glass fiber.Its expected service life exceeded 50 years.So,the stability of 5·1·8 was the important factor for noncorrision of glass fiber and long-term durability of high performance GRMC board.