玻璃纤维对混凝土收缩开裂性能的影响研究

摘要

The influence of glass fiber on flexural strength,compressive strength and drying shrinkage performance of cement mortar was tested.Based on this,the method of plate was used to study the effect of the amount of doped glass fiber and superplasticizer on early plastic cracking performance of concrete,which is evaluated through the initial cracking time,maximum crack width,the total crack area per unit area of concrete.When glass fiber volume fraction in cement mortar is 1.0%,its 28 d flexural strength can be close to 10 MPa,and the shrinkage rate is 0.089%.When volume fraction of glass fiber is 0.25%,the initial cracking time and maximum crack width decreased obviously,and the total crack area per unit area of concrete can reduce close to 80%;when volume fraction increases to 0.5%,glass fiber can completely inhibit the formation of concrete early crack.The experimental results show that,glass fiber can enhance the flexural strength of cement mortar,and inhibit drying shrinkage of cement mortar and early crack forma-tion and development of cement significantly.%测试了玻璃纤维对水泥砂浆抗折强度、抗压强度以及干燥收缩性能的影响规律,在此基础上,利用平板法研究了玻璃纤维掺量对混凝土早期塑性开裂性能的作用,并通过混凝土的初始开裂时间、最大裂缝宽度、单位面积总开裂面积评价其影响效果。当水泥砂浆中掺加体积掺量为1.0%的玻璃纤维时,其28 d 抗折强度接近10 MPa,干燥收缩率为890×10-6；当混凝土中掺加0.25%的玻璃纤维时,混凝土初始开裂时间和最大裂缝宽度明显降低,单位面积总开裂面积降低幅度接近80%；体积掺量增加到0.5%时,玻璃纤维能够完全抑制混凝土早期裂缝的形成。实验结果表明,玻璃纤维能够增强水泥砂浆的抗折强度,明显抑制水泥砂浆和混凝土的干燥收缩以及早期裂缝的形成和发展。