耐碱玻纤和粉煤灰对轻质混凝土强度及冻融耐久性的影响研究

Experimental Study on Strength and Freeze-thaw Durability of Alkali-Resistant Glass Fiber Fly Ash Lightweight Concrete

以陶粒为粗骨料制备了轻质混凝土试件,研究了耐碱玻纤、粉煤灰增强材料对轻质混凝土的力学性能及冻融耐久性的影响。结果表明,随着耐碱玻纤掺量的增加,同一龄期轻质混凝土试件的抗压强度、抗拉强度先增大后减小;过高的耐碱玻纤掺量不利于强度的增长,且耐碱玻纤对试件抗拉强度的影响大于抗压强度,其最优掺量为0.6 kg/m^3;掺入适量的粉煤灰(≤15%)能提高轻质混凝土的强度,提升幅度与掺量成正比,但掺量较大时对强度不利;与未掺耐碱玻纤的试件相比,当耐碱玻纤掺量低于0.6 kg/m^3和1.0 kg/m^3时,能分别提升试件的相对动弹性模量和降低质量损失率,改善幅度与耐碱玻纤的掺量正相关;粉煤灰掺量低于15%时有利于提高试件的冻融耐久性,但掺量较高(≥20%)则会降低试件的冻融耐久性指标。

Lightweight concrete specimens were fabricated with ceramsite as coarse aggregate, and the effects of reinforced materials as alkali-resistant glass fiber and fly ash on the mechanical properties and freeze-thaw durability of lightweight concrete were studied. The results show that with the increase of alkali-resistant glass fiber content, the compressive and tensile strength of lightweight concrete at the same age increase first and then decrease. Excessive alkali-resistant glass fiber content is not conducive to the increase of strength, and the influence of alkali-resistant glass fiber on the tensile strength of specimens is greater than that of compressive strength, and the optimal content is 0.6 kg/m^3.The strength of lightweight concrete can be improved by adding appropriate amount of fly ash(≤15%), and the increasing range is proportional to the amount of fly ash, but it is unfavorable to the strength when the amount of fly ash is large.Compared with the specimens without alkali-resistant glass fiber, when the content of alkali-resistant glass fiber is less than 0.6 kg/m^3 and 1.0 kg/m^3, the relative dynamic elastic modulus and mass loss rate of specimens can be increased respectively, and the improvement range is positively correlated with the content of alkali-resistant glass fiber. When fly ash content is less than 15%, it is beneficial to improve the freeze-thaw durability of the specimens, but the high fly ash content(≥ 20%) will seriously reduce the freeze-thaw durability index of the specimens.