改性聚丙烯纤维增强磷酸镁水泥砂浆的力学性能研究

增强磷酸镁水泥砂浆(MPCM)的抗弯韧性有利于促进其在混凝土路面修复领域的应用。为了增强MPCM的抗弯韧性,对比研究了未处理和硅烷偶联剂预处理的聚丙烯纤维对MPCM抗弯韧性的影响,分析了预处理聚丙烯纤维增韧MPCM的机制。结果表明,聚丙烯纤维质量掺量0.4%时,MPCM7d抗折强度增大23.5%;6-10mm聚丙烯纤维有利于提高MPCM的抗压强度,而10-19mm聚丙烯纤维更有利于提高MPCM的抗折强度;未处理聚丙烯纤维与磷酸镁水泥(MPC)水化产物之间为物理作用,聚丙烯纤维并未充分发挥增韧效果;用浓度20%的硅烷偶联剂溶液改性处理30~60min有利于改善聚丙烯纤维与MPC水化产物的界面粘结,使MPC水化产物和预处理后的聚丙烯纤维产生嵌合作用,显著地增强了MPCM的抗弯韧性。

Study on Mechanical Properties of Modified Polypropylene Fibers Reinforced Magnesium Phosphate Cement Mortar

The flexural toughness of magnesium phosphate cement mortar (MPCM)can boost its application in reinforcing and repairing concrete struc-ture. To toughen MPCM, the effects of untreated and pretreated PPF on the mechanical properties of MPCM are studied, with the toughening mechanism of PPF analyzed. The results show that with 0.6%of PPF the flexural strength of MPCM is increased by 43.3%;PPF with a length of 3-6mm is more con-ducive to improve the compressive strength of MPCM, and the length of 6-12mm is propitious to improve the flexural strength of MPCM. The properties of MPCM toughened by PPF are not much improved because of physical bond between untreated PPF and hydration products of MPC. Pretreated PPF immersed in 20%silane coupling agent for 30~60min help to promote the interface bonding between PPF and hydration products of MPC. Based on chimerical reaction between hydration products and pretreated PPF, the mechanical and toughening properties of MPCM are significantly improved.