吉 飞1,焦宝祥2,丘 泰1
尿素对磷酸镁水泥凝结时间和水化放热的影响
吉 飞1,焦宝祥2,丘 泰1
摘 要:研究了尿素对磷酸镁水泥(MPC)凝结时间和水化放热过程的影响。结果表明,在磷酸二氢钾与氧化镁质量比为1:3、水胶比为0.16时,单独添加尿素作为缓凝剂,对MPC凝结时间和水化放热影响不显著。当尿素和硼砂同时添加时,体系的凝结时间和水化放热曲线有显著的不同。在硼砂量为磷酸二氢钾与氧化镁质量总和的1%时,随尿素添加量的增加,MPC的凝结时间显著延长,其第一和第二水化放热峰峰高显著降低;但当硼砂添加量达2.5%时(在尿素掺量相同的情况下),体系的凝结时间又有所缩短,水化放热峰峰值相应增高。
Abstract: The effects of urea on setting time and hydration exothermic process of magnesium phosphate cement (MPC) are studied. The results show that the effects of urea on setting time and hydration exothermic process are not obvious if it is used as the single retarder in the MPC, which is designed by the potassium dihydrogen phosphate and magnesium oxide with a mass proportion of 1:3 and a water to solid ratio of 0.16. If urea and borax are added together, the setting time and hydration exothermic curves are obviously different. When the addition of borax is 1 % of the sum weight of potassium dihydrogen phosphate and magnesium oxide in the MPC, the setting time increases and the intensity for the first and the second hydration exothermic peaks significantly decreases with the increase of the urea content. However, when the addition of borax reaches 2.5% and the addition of urea is constant, the setting time decreases and the intensity of hydration exothermic peaks increases accordingly.
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