早期温湿度条件对柠檬酸改性硫氧镁胶凝材料性能的影响及机理

Effects and Mechanism of Early Temperature and Humidity on Properties of Modified Magnesium Oxysulfate Cementitious Materials

为了确定柠檬酸改性硫氧镁(CMOs)胶凝材料的早期温湿度稳定性,分别研究了早期养护温湿度对其力学性能及耐水性能的影响,并采用SEM、XRD及TG测试技术对其影响机理进行了分析。结果表明:CMOs早期力学性能和耐水性随着早期养护温度升高先提高后降低,35℃左右其3d抗折强度达到最大值10.4 MPa,3d抗压强度达到最大值68.0 MPa,浸水46d后软化系数达到0.9;而后期力学性能和耐水性则随着早期养护温度的提高有不同程度的降低;结果还发现相同早期养护温度时早期饱水养护大大降低CMOs的力学性能和耐水性。同时微观结构分析表明,早期养护温度的升高可以使CMOs水化反应更充分,结构相对比较致密,从而使其早期力学性能有明显提高,但水化后期CMOs结构稳定性随着早期养护温度的升高而明显降低,从而导致其后期强度有不同程度的降低。

In order to determine early temperature and humidity related stability of citric-acid modified magnesium oxysulfate(CMOs)cementitious materials,the effects and influencing mechanism of different early curing temperature and humidity on mechanical properties and water resistance of CMOs were investigated.The results show that the early mechanical property of CMOs materials increases first and then decreases with the increase of the early curing temperature.At about 35 ℃ the maximum value of flexural strength,compressive strength and water resistance coefficient with 46 days immersion reach 10.4 MPa,68.0 MPa and 0.9 respectively;While the late mechanical property and water resistance of CMOs material decreases with the increase of the early curing temperature.Furthermore,the mechanical properties and water resistance of CMOs materials with steam curing significantly decreases.At the same time,micro-analysis results show that the hydration reaction of CMOs materials can be more complete because of the increase of the early curing temperature so that the early mechanical properties improve significantly.While the later structural stability deceases with the increase of the early curing temperature,which leads to the decrease of its mechanical properties at the later stage.