【摘要】 石膏基胶凝材料强度低、耐水性差是限制其制品应用的主要原因,通过内掺不同种类的可溶盐（Na₂CO₃、Na₃PO₄、BaCl₂、Na₂C₂O₄）对建筑石膏进行改性,分析盐溶液种类及浓度对半水石膏凝结硬化过程、二水石膏硬化体力学性能及耐水性能的影响。结果表明:Na₂CO₃、BaCl₂对半水石膏凝结时间基本无影响,但两者均导致二水石膏硬化体力学性能的下降;Na₃PO₄大幅延缓了半水石膏水化进程,使硬化体力学性能大幅下降;Na₂C₂O₄对半水石膏具有显著的促凝作用,二水石膏硬化体抗折、抗压强度及耐水性能大幅提高,吸水率略有下降,Na₂C₂O₄溶液优化质量分数为0.18%。SEM测试分析表明,可溶盐Na₂C₂O₄使二水石膏晶体细化、长径比增大、晶体搭接密实度增加。更多还原

【Abstract】 Low strength and bad water-resistance are the main limited factors for the application of gypsum-based productions. Influences on setting times, mechanical properties and water-resistance property are investigated by mixing gypsum plasters together with different kinds of solvable salts solutions as modifiers including Na₂CO₃, Na₃PO₄, BaCl₂ and Na₂C₂O₄. Results indicated that Na₂CO₃ and BaCl₂ have little influences on the setting and hardening process of hemihydrate gypsum while the mechanical properties are decreased by modification. The setting and hydration processes are lengthened significantly by Na₃PO₄ accompanying with the sever decline of mechanical properties. However, the setting times are greatly shortened by the blending with Na₂C₂O₄. Meanwhile, the flexural strength, compressive strength and water-resistance property are all increased while the water absorption is decreased finally. The optimal dosage is 0.18% for Na₂C₂O₄. The SEM analyses show that the gypsum crystal size is refined and the ratio of length to diameter is increased to make a compacter micro-structure.更多还原