短切纤维增强水泥基胶凝材料力学性能研究

Study on mechanical properties of short fiber reinforced cement-based cementitious materials

为了改善油气井固井用硅酸盐水泥石的性能,通过测试水泥浆工程性能、水泥石力学性能及渗透性,结合SEM和XRD分析其微观结构及水化产物,探讨了两种纤维在增强水泥石力学性能方面的耐温耐久对比及作用机制。结果表明:1.0%的纤维对水泥浆工程性能促进效果最好;90℃下,玄武岩纤维耐温耐久性能较差,在水泥基体中被完全腐蚀,促进水泥水化产物及微裂缝的生成同时增强了水泥石强度,28 d后,水泥石抗压强度相比于空白样提高了16.71%;同龄期下,相比于空白样,耐碱玻璃纤维水泥石抗压强度降低了9.88%,抗折与抗拉强度分别提高了33.43%和23.17%,弹性模量降低了32.38%。表明耐碱玻璃纤维虽然一定程度上抑制了强度的发展,但其能够在水泥基体中稳定存在并能限制微裂缝的产生及扩展,拔出过程中消耗了大量能量,从而提高了水泥石的韧性。

In order to improve the properties of Portland cement used for cementing oil and gas wells,the temperature resistance and durability of two kinds of fibers in enhancing the mechanical properties of Portland cement were discussed by testing the engineering properties of cement slurry,mechanical properties and permeability of cement,and analyzing the microstructure and hydration products by SEM and XRD.The results showed that 1.0%fiber had the best effect on improving the engineering properties of cement slurry,the basalt fiber had poor temperature resistance and durability at 90°C,and was completely corroded in cement matrix,which promoted the formation of hydration products and microcracks of cement and the strength of cement was enhanced at the same time.After 28 days,the compressive strength of the cement stone increased by 16.71%compared with the blank sample.At the same age,compared with that of the blank sample,the compressive strength of alkali resistant glass fiber cement decreased by 9.88%,the flexural strength and tensile strength increased by 33.43%and 23.17%respectively,and the elastic modulus decreased by 32.38%.The results showed that although alkali resistant glass fiber inhibited the development of strength to a certain extent,it can stably exist in the cement matrix and limit the generation and expansion of micro-cracks,which consumed a lot of energy in the pulling out process,thus improving the toughness of the cement.