改性聚丙烯纤维对发泡水泥性能的影响

采用丙烯酸化学接枝法对聚丙烯纤维进行表面改性, 研究了改性聚丙烯纤维对发泡水泥塑性收缩开裂、 力学性能及泡孔结构的影响。结果表明, 改性聚丙烯纤维可改善发泡水泥的泡孔结构, 并降低其塑性收缩开裂、 细化其塑性收缩裂缝, 同时可提高其抗折、 抗压强度及弯曲韧性。纤维与水泥的质量比为0.7%时, 试样的泡孔结构明显改善, 塑性收缩开裂值下降了85.4%, 且缝宽小于1 mm的塑性收缩裂缝比例高达73.1%, 同时试样抗折及抗压强度分别增加48.8%和30.3%, 弯曲韧性显著增加。利用傅里叶变换红外光谱仪、 SEM、 光学显微镜对改性前后聚丙烯纤维表面基团及发泡水泥试样的断面微观形貌、 泡孔结构进行了分析, 探讨了改性聚丙烯纤维的作用机制。

Effects of modified polypropylene fibers on properties of foamed cement

Polypropylene (PP) fibers surface was modified with acrylic acid by chemical grafting method. The effects of modified PP fibers on plastic shrinkage cracking, mechanical properties and bubbles structure of foamed cement were studied. The results show that modified PP fibers can improve bubbles structure, reduce plastic shrinkage cracking and refine plastic shrinkage cracks of the foamed cement, and it can increase flexural strength, compressive strength and flexural toughness. When the mass ratio of modified PP fibers to cement is 0.7%, the bubbles structure of foamed cement is improved significantly, and the plastic shrinkage cracking value decreases by 85.4%, while plastic shrinkage cracks whose width is less than 1 mm is as high as 73.1%. In the meantime, the flexural strength and compressive strength increase by 48.8% and 30.3%, respectively, and flexural toughness increase significantly. The surface groups of PP fibers before and after modification and the fracture surface micro-morphology and bubbles structure of foamed cement were observed by FTIR spectrometer, SEM and optical microscope. The action mechanisms of modified PP fibers were discussed.