再生纤维素纤维增强水泥砂浆的早期抗裂和自收缩行为

早期收缩开裂是导致混凝土劣化的重要因素之一，纤维的加入可以延缓甚至减少裂缝的延伸及扩展。使用具有吸水特性的再生纤维素纤维，与UF500纤维素纤维和无吸水的聚丙烯短纤维对比，研究再生纤维素纤维对水泥砂浆早期抗裂和自收缩行为的影响规律。将掺量为水泥质量1%或2%的各类纤维掺入水泥砂浆，密封养护，分析水泥砂浆强度、折压比及自收缩应变。研究结果表明：水灰比0.3时，添加再生纤维素纤维不能增强砂浆的抗裂性能和自收缩性能；水灰比大于0.35时，添加1%的再生纤维素纤维虽然降低了砂浆的抗折强度和抗压强度，但提高了该样品的折压比，增强了砂浆的抗裂性能和减缩效应。

Early-age cracking resistance and self-shrinkage behavior of recycled cellulose fibers-reinforced cement mortar

Early shrinkage cracking is one of the important factors leading to the deterioration of concrete, the elongation and extension of cracks can be slowed down or even reduced by adding fibers. The objective of this article was to study the influence rules of regenerated cellulose fibers (RCFs) on the early cracking and the self-shrinkage of cement mortar under the sealed curing. The recycled cellulose fiber, UF500 cellulose fiber and non-absorbent polypropylene staple fiber were compared. The strength, the ratio of flexural strength to compressive strength and the self-shrinkage strains of cement mortar with fibers mixed at 1% or 2% by mass were analyzed. The results showed that the crack-resistance and self-shrinkage could not be improved by adding RCFs when the cement mortar at 0.3 water-cement ratio. When water-cement ratio was higher than 0.35, the ratio of flexural strength to compressive strength of mortar increased by adding 1% RCFs although it decreased the flexural strength and the compressive strength. Then under the quantity, the crack-resistance and shrinkage-reducing effect of cement mortar were enforced, too.