不同龄期下双掺矿物掺合料对GRC构件抗弯、抗冲击强度及抗渗性能的影响

针对实际工程应用中玻璃纤维增强水泥(GRC)试件存在表面微裂纹以及在潮湿环境下强度和韧性较低等问题,采用加速老化法(50 ℃热水加速老化)对双掺矿物掺合料以改性普通硅酸盐水泥为基材的GRC试件抗弯强度、抗冲击强度以及抗渗性能进行试验,并通过扫描电镜试验分析GRC试件玻璃纤维网格布表面的侵蚀情况。结果表明:无论是在50 ℃热水加速老化条件下还是在自然环境下,提高GRC试件抗冲击强度的最佳掺量(质量分数)为10%硅灰和20%偏高岭土; 双掺10%硅灰、20%粉煤灰以及双掺10%硅灰、20%偏高岭土能够显著提高GRC试件抗弯强度; 双掺20%粉煤灰、20%偏高岭土的GRC试件抗渗性能优异; 玻璃纤维网格布侵蚀程度与其宏观力学性能呈负相关; 掺入一定比例的矿物掺合料可以改善玻璃纤维网格布的抗侵蚀性能,同时改善界面区微观结构,对GRC试件的耐久性能有较大提升。

Effect of Double Mineral Admixtures on Flexural Strength,Impact Strength and Impermeability of GRC Members at Different Ages

In practical engineering applications, glass fiber reinforced cement(GRC)specimens had some problems, such as surface microcracks, low strength and low toughness in humid environment. The accelerated aging method(50 ℃ hot water accelerated aging)was used to study the flexural strength, impact strength and impermeability of the GRC specimens with double mineral admixtures and modified universal silicon cement as the base material, and the erosion of the surface of the glass fiber mesh cloth of the GRC specimen was analyzed by scanning electron microscope. The results show that the best addition amount(mass fraction)to improve the impact strength of GRC specimen is 10% silica fume and 20% metakaolin under the accelerated aging of hot water at 50 ℃ or in the natural environment. The effect of double mixing 10% silica fume and 20% fly ash or 10% silica fume and 20% metakaolin on improving the bending strength is obvious. The impermeability of the GRC specimen with 20% fly ash and 20% metakaolin is excellent. The erosion degree of the glass fiber mesh is negatively related to the macroscopic mechanical properties, and a certain proportion of mineral admixtures can improve the corrosion resistance of the glass fiber mesh cloth and improve the microstructure of the interface zone, and the durability of the GRC specimen is greatly improved.