石膏基复合材料改性研究

Study on Modification of Gypsum Matrix Composites

研究了单掺石灰(CaO)、水泥、页岩陶粒、草纤维对石膏基复合材料(GMC)力学性能和耐水性能的影响规律。结果表明,5%掺量石灰能提高GMC湿强度,降低吸水率,提高抗折软化系数;5%掺量水泥能提高GMC 28 d干湿抗压和抗折强度,明显降低吸水率,大幅提高抗折软化系数;陶粒能提高GMC干抗压强度,降低吸水率,掺量为10%时可提高GMC干抗折强度;草纤维仅在掺量为1%时对GMC干抗折强度有积极影响。SEM分析结果表明,掺入过多(20%)石灰会使石膏晶体生长不完全,出现晶体缺陷,导致强度降低;掺加水泥会改变石膏晶体大小和形状,且水泥水化产物钙矾石具有填充作用,水化硅酸钙(C-S-H)凝胶具有填充和胶结作用,提高了GMC致密性,但水泥过多会产生不利影响。

The effects of lime(CaO),cement,ceramsite and grass fiber on the mechanical properties and water resistance of gypsum matrix composites(GMC)were studied.The results show that the 5%lime can improve the wet strength of GMC,reduce its water absorption and improve its flexural softening coefficient;5%cement can improve the 28d dry/wet compressive and flexural strength of GMC,reduce its water absorption and greatly improve its flexural softening coefficient significantly;ceramsite can improve the dry compressive strength of GMC and reduce its water absorption,10%ceramsite can improve its dry flexural strength;only when the content of grass fiber is 1%,it has a positive effect on the dry flexural strength of GMC.SEM analysis shows that adding 20%lime will make the gypsum crystal grow incompletely,appear crystal defects and reduce the strength;the addition of cement will change the size and shape of gypsum crystals,and the cement hydration product ettringite has a filling effect,C-S-H gel has filling and cementation effect to improve GMC compactness,but excessive cement will have adverse effects.