环境湿度对玻璃纤维增强水泥力学性能的影响

Effects of ambient humidity on mechanical properties of glass fiber reinforced cement

通过开展在不同龄期、不同环境湿度下玻璃纤维增强水泥(GRC)试件的抗折强度、抗压强度试验和基体pH值测定,研究了环境湿度对掺加粉煤灰和硅灰等活性矿物掺合料的GRC试件力学性能的影响。结果表明:环境湿度对GRC试件的抗折强度有重要影响,相对湿度越大,随着龄期增加,GRC试件抗折强度降低越严重;在温度60℃、相对湿度95%条件下,经过56d龄期后,掺有40%粉煤灰和10%硅灰的GRC试件抗折强度比未掺加粉煤灰和硅灰的GRC试件的抗折强度提高48.5%、抗压强度提高23.6%,GRC基体pH值降低6%。在相同的湿度条件下,掺有粉煤灰和硅灰试件的pH值在各个龄期都低于普通硅酸盐水泥试件,说明粉煤灰和硅灰的掺入能降低水泥水化液相的碱度,进而延缓了纤维受侵蚀的速度,显著改善了GRC试件的力学及耐久性能。通过对试验结果进行分析,利用MATLAB软件建立了GRC试件抗折强度和抗压强度与水泥砂浆基体pH值及时间的关系式。

Through the determination of flexural strength,compressive strength test and matrix pH value test of glass fiber reinforced cement （GRC）specimens under different ages and ambient humidities,the effects of ambient humidity on the mechanical properties of GRC specimens blended with active mineral admixtures of fly ash and silica fume were researched.The results show that the ambient humidity has a significant effect on the flexural strength of GRC specimens.With the increase of the age,the higher relative humidity is,the more flexural strength of GRC specimens reduces.After 56 d age on the condition of temperature of 60 ℃ and relative humidity of 95%,the flex-ural strength and compressive strength of GRC specimens blended with 40% fly ash and 10% silica fume both in-crease by 48.5% and 23.6% respectively,meanwhile the pH value of GRC matrix decreases by 6% in comparison to those without fly ash and silica fume.On the same condition of ambient humidity,the pH values of specimens blended with fly ash and silica fume are lower than those of ordinary portland cement specimens in every age,which shows that the addition of fly ash and silica fume can reduce the alkalinity of cement hydration liquid phase and slow down the corrosion rate of fibers.So it can dramatically improve the mechanical property and durability of GRC specimens.Based on the analysis of the test results and MATLAB software,the mathematical relationship between the mechanical properties of GRC specimens including the flexural strength and compressive strength and the pH value of cement mortar matrix,the age can be established.