磷酸及磷酸盐对木屑/氯氧镁水泥复合材料的性能影响研究

The Study of the Effects of Phosphoric Acid and Phosphate on the Performance of Sawdust/Magnesium Oxychloride Cement Composite Materials

摘要: 木屑/氯氧镁水泥复合材料由氯氧镁水泥为基体、木屑为增强材料制成。本文通过在木屑/氯氧镁水泥添加磷酸(H₃PO₄)、磷酸二氢纳(NaH₂PO₄)、磷酸氢二钠(Na₂HPO₄)与磷酸钠(Na₃PO₄)。研究了不同掺量的磷酸及其可溶性磷酸盐对木屑/氯氧镁水泥的抗压强度，抗折强度及耐水性的影响。结果表明：磷酸、磷酸二氢纳、磷酸氢二钠的加入会降低木屑/氯氧镁水泥的强度，且随着掺量的增加强度降低；0.5%掺量的磷酸钠会使木屑/氯氧镁水泥抗压强度增强8.87%，2.0%掺量的磷酸钠会使木屑/氯氧镁水泥抗压强度降低17.28%；磷酸和磷酸二氢纳对木屑/氯氧镁水泥的耐水性有明显的改善，0.5%掺量的磷酸和1.0%掺量的磷酸二氢纳的改善效果最为明显，软化系数分别为0.91和0.96；磷酸根阴离子会改变5相晶体的形貌、阻碍5相的水解、生成难溶性磷酸盐的保护作用等多因素协同改善木屑/氯氧镁水泥的耐水性。

Abstract: Sawdust/magnesium oxychloride cement composite is made up of magnesium oxychloride cement as the matrix and wood chips as reinforcing material. This study investigated the effects of different concentrations of phosphoric acid (H₃PO₄), monosodium phosphate (NaH₂PO₄), disodium hydrogen phosphate (Na₂HPO₄), and trisodium phosphate (Na₃PO₄) on the compressive strength, flexural strength, and water resistance of sawdust magnesium oxychloride cement composite. The results indicate that the addition of phosphoric acid, monosodium phosphate, and disodium hydrogen phosphate lowers the strength of sawdust magnesium oxychloride cement composite, with a decrease in strength as the dosage increases; 0.5% of trisodium phosphate increases the compressive strength of t sawdust magnesium oxychloride cement composite by 8.87%, while 2.0% has the opposite effect, reducing the compressive strength by 17.28%; Phosphate and disodium hydrogen phosphate significantly improve the water resistance of sawdust magnesium oxychloride cement composite, with the most marked effects observed at 0.5% phosphate and 1.0% disodium hydrogen phosphate, resulting in softening coefficients of 0.91 and 0.96, respectively; Phosphate anions alter the morphology of the 5-phase crystals and hinder the hydrolysis of the 5 phase while generating the protective effect of insoluble phosphate salts, synergistically improving the water resistance of sawdust magnesium oxychloride cement composite.