柠檬酸对杨木粉与硫氧镁水泥混合物水化特性和抗折强度的影响

Study of the effect of Citric Acid on the flexural strength and composites of Aspen Powder and Magnesium Oxysulfate Cement

为了降低硫氧镁水泥水化反应速率,提高其力学性能及耐水性能,在杨木粉与硫氧镁水泥混合物中添加不同比例柠檬酸,采用中控仪表检测混合物固化过程中的温度变化,以及采用力学试验机检测养护后混合物试件的抗折性能,并测试其耐水性。结果表明:杨木粉具有降低水化温度以及放热量的作用,并提高了水泥混合物的密度,使得空隙率降低且增强试件的力学性能;养护时间越长,混合物试件性能更稳定;柠檬酸具有阻凝作用,降低混合物反应温度的同时减少了放热量,并且最高反应温度峰值延后;随着柠檬酸添加量的增加,混合物的抗折强度越强,耐水性越好。

In order to reduce the hydration heat rate of magnesium oxysulfate cement, and improve the mechanical properties and water resistance, this paper aimed at the influence analysis of the hydration process, flexural strength and water resistance of aspen powder/magnesium oxysulfate cement composites under the conditions of different proportions of citric acid by using control instrument to test the temperature changes of mixture in the process of solidificationand and mechanical testing machine to detect the flexural performance of mixture specimen after curing. Results indicate that aspen powder obviously reduces the hydration temperature and heat release of the magnesium oxysulfate cement and makes the performance more stable, which shows the aspen powder and the magnesium oxysulfate cement have a good phase eligibility, even more, it increases the density of the cement mixture and enhances the mechanical properties of the specimens by reducing the void fraction; furthermore, the longer the curing time, the performance of the mixture specimen is more stable; aspen powder-citric acid as additive reduces the maximum temperature and the total heat release of aspen powder/magnesium oxysulfate cement composites, and delays the appearance of the highest peak; the flexural strength and the resistance to water of magnesium oxysulfate cement are greatly improved by increasing the amount of citric acid. When the addition of the citric acid is 1.5% and the curing time is 28 d, various performances of the mixture specimen are the best.