聚丙烯纺黏/机织复合土工布的制备及其污泥脱水性能

Manufacturing and sludge dewatering performance of polypropylene spun-bonded/woven composite geotextiles

为满足土工布材料高强度、高过滤性的生产要求,以聚丙烯长丝机织土工布为基材,聚丙烯纺黏针刺非织造土工布为面层,采用针刺复合工艺并调节针刺密度制备了一系列聚丙烯纺黏/机织复合土工布,系统探讨了针刺密度对聚丙烯纺黏/机织复合土工布力学和水力学性能的影响。分别采用压力过滤测试和落差脱水测试评估土工布对粉煤灰浆的脱水性能。结果表明:当针刺密度大于35刺/cm2时,复合土工布的纵/横向拉伸强度均表现出明显的下降;剥离强力和透水率随针刺密度的增大而增大,但选用的针刺密度对顶破强力和有效孔径(O98)没有明显影响。复合土工布的颗粒透过率低于单层机织布;初始阶段滤液流速的大小取决于土工布的透水率,但是,随着污泥在土工布上的沉积,滤饼的性质将主导滤液的流速。

In order to meet the requirements of high strength and high filtration of geotextile materials,a series of polypropylene spun-bonded/woven composite geotextiles were manufactured by laminating a polypropylene spun-bonded needle-punched nonwoven geotextile over polypropylene filament woven geotextile by adopting needle-punching process and adjusting punch densities.The effects of punch density on mechanical and hydraulic properties of polypropylene spun-bonded/woven composite geotextiles were systematically discussed.In addition,the pressure filtration test and falling-head dewatering test were performed to evaluate the dewatering performance of geotextiles for fly ash slurries.The results show that the tensile strength in MD/CD of composite geotextiles display significant reduction when punch density is higher than 35 stitch/cm2.The peeling strength and permeability increase with punch density;however,the adopted punch density has no obvious effect on the puncture strength and apparent pore size(O98).The piping rate of composite geotextile that laminates a spun-bonded needle-punched nonwoven geotextile is lower than that of simple woven.The flow rate at the initial stage of dewatering depends on the permittivity of geotextile;however,with the settling of slurry on geotextile,the permeability of the filter cake determines the flow rate of the filtrate.