通过吸水率、软化系数、抗折强度和抗压强度试验, 并结合傅里叶红外光谱和扫描电子显微镜测试, 探究不同长度和掺量的苎麻纤维对苎麻纤维增强磷建筑石膏复合材料耐水性能和力学性能的影响。研究结果表明, 掺入适量苎麻纤维可改善苎麻纤维增强磷建筑石膏复合材料的耐水性能和力学性能, 以及提高复合材料的延性。掺入0.5%(体积分数, 下同)的10 mm苎麻纤维时, 复合材料的软化系数达到最大, 较空白组提高20.0%。苎麻纤维的掺入能有效提高复合材料的抗折强度, 28 d时, 掺入1.5%的10 mm苎麻纤维试样较空白组抗折强度提高39.5%。掺入小于20 mm的苎麻纤维会降低复合材料的抗压强度, 掺入不超过1.5%的30 mm苎麻纤维可提高复合材料的抗压强度, 28 d时, 掺入1.5%的30 mm苎麻纤维试样较空白组抗压强度提高10.1%。苎麻纤维在复合材料基体内会发生水解, 随龄期的增长水解程度加重, 表面逐渐粗糙。

The effects of different length and content of ramie fibers on the water resistance and mechanical properties of ramie fiber reinforced calcined phosphogypsum composite materials were studied through the tests of water absorption, softening coefficient, flexural strength and compressive strength, combined with Fourier transform infrared spectroscopy and scanning electron microscopy. The results show that adding ramie fiber can improve the water resistance and mechanical properties of ramie fiber reinforced calcined phosphogypsum composite materials, and also promote the ductility of composite materials. Adding 0.5% (volume fraction, the same below) 10 mm ramie fiber makes the softening coefficient of composite materials reach the maximum, which increases by 20.0% compared with the control sample. The incorporation of ramie fiber can effectively improve the flexural strength of composite materials. At the age of 28 d, the flexural strength of composite materials with 1.5% 10 mm ramie fiber increases by 39.5% compared with the control sample. The compressive strength of composite materials with less than 20 mm ramie fiber decreases, but increases by addition of less than 1.5% 30 mm ramie fiber. At the age of 28 d, the compressive strength of composite materials with 1.5% 30 mm ramie fiber increases by 10.1% compared with the control sample. Ramie fiber hydrolyzes in the composite materials matrix. The degree of hydrolysis increases and the surface becomes rougher with the increase of age.