水泥聚丙烯纤维复合稳定特细沙材料干缩性能研究
Study on Dry Shrinkage Properties of Cement Polypropylene Fiber Composite Stabilized Extra Fine Sand Material

孟加拉达卡绕城高速公路是一带一路工程重要项目，为解决该地区无碎石问题，将当地资源丰富的极细河沙用作为水泥稳定特细沙底基层和路基稳定层的材料，但在施工过程中，受沙材料来源多样性和高热环境因素的影响，水泥稳定特细沙材料易发生收缩开裂，引发路面反射裂缝。为了解决这一问题，本文通过在水泥稳定特细沙中掺入聚丙烯纤维，以降低干缩现象。通过干燥收缩试验，研究了0.075 mm通过率为0%、6.5%、13%，纤维长度为6 mm、9 mm、12 mm和掺量为0.3‰、0.5‰、0.7‰的聚丙烯纤维对水泥稳定特细沙干缩性能的影响。结果表明，0.075 mm筛孔通过率越大，细度模数越小，水泥稳定特细沙的干缩系数越大，在纤维长度9 mm，掺量0.5‰时，水泥稳定特细沙13的干缩系数较水泥稳定特细沙6、水泥稳定特细沙0分别大6.4%、14.0%；聚丙烯纤维长度小于9 mm时，随掺入纤维长度增加，水泥稳定特细沙干缩系数降低，之后又有所增大；随聚丙烯纤维掺量的增多，水泥稳定特细沙干缩系数持续减小；综合考虑纤维长度、掺量与0.075 mm筛孔通过率对干缩性能的影响效果，建议纤维长度为9 mm，掺量为0.5‰，0.075 mm筛孔通过率小于等于6.5%的水泥稳定特细沙材料有较优的抗干缩性能。
Dhaka Bypass Expressway in Bangladesh is an important project of Belt and Road Project. In order to solve the problem of no gravel in the area, the local resource-rich very fine river sand is used as the material of cement stabilized extra fine sand sub-base layer and road base stabilized layer, but in the process of construction, affected by the diversity of the source of the sand material and the environmental factors of high heat, the cement stabilized extra fine sand material is susceptible to shrinkage and cracking, which triggers the reflective cracking of the road surface. In order to solve this problem, this paper reduces the dry shrinkage phenomenon by blending polypropylene fibers in cement stabilized extra fine sand. Through the dry shrinkage test, the effect of polypropylene fibers with 0.075 mm passage rate of 0%, 6.5%, 13%, fiber length of 6 mm, 9 mm, 12 mm and dosage of 0.3‰, 0.5‰, 0.7‰ on the dry shrinkage performance of cement stabilized extra fine sand was investigated. The results show that the larger the 0.075 mm sieve throughput rate, the smaller the fineness modulus, the larger the dry shrinkage coefficient of cement stabilized extra fine sand, in the fiber length of 9 mm, the dosage of 0.5‰, the dry shrinkage coefficient of cement stabilized extra fine sand 13 compared with the cement stabilized extra fine sand 6, the cement stabilized extra fine sand 0, respectively, larger by 6.4%, 14.0%; polypropylene fibers with a length of less than 9 mm, with the increase of the doped fiber length, the dry shrinkage coefficient of cement stabilized extra fine sand 13 is larger than the cement stabilized extra fine sand 6 and cement stabilized extra fine sand 0, respectively. Cement stabilized extra fine sand shrinkage coefficient decreased, and then increased; with the increase