砂的细度对水泥基材料性能的影响

Effect of Sand Fineness on the Properties of Cement Based Materials

本文选用了四种不同粒径的砂(粗砂、中砂、细砂和特细砂),考虑了两种不同的水灰比(0.35和0.5),研究了砂的细度对砂浆力学性能、自由收缩性能、抗开裂性能和微观结构的影响。其中通过力学性能试验测定了试件的抗压强度和抗折强度;采用直接长度的测量方法测定试件不同龄期的自由收缩量;采用圆环试验方法研究砂浆的抗开裂性能,在钢环内表面黏贴应变片,通过测得的应变计算砂浆的约束应力;对试样进行扫描电镜试验,观察砂和水泥石的界面过渡区的微观结构。试验结果表明,砂的粒径对砂浆的力学性能、自由收缩、约束收缩和微观结构都有较大影响。使用特细砂的砂浆各项性能均最差;使用中砂的砂浆各项性能最好,尤其是其自由收缩和抗开裂性能。

Considering the two kinds of different water cement ratio(0. 35 and 0. 5),four kinds of different particle sizes of sand(coarse sand,medium sand,fine sand and especially fine sand) were used to study the influences of sand fineness on the mechanical properties,free shrinkage performance,cracking resistance and microstructure of mortars. The compressive strength and flexural strength of the specimens were tested as mechanical properties. The free shrinkage of the specimens on different ages were tested through directly length measuring method. The cracking resistance of the mortars were evaluated by ring tests,and strain gauges were pasted on inside of the steel ring,then,the constraint stress of the mortar was calculated through the measured strain. Scanning electron microscopy was carried out on the samples,interface microstructure of transition zone was observed. The experimental results show that the sizes of sand influence greatly on mechanical properties,free shrinkage performance,cracking resistance and microstructure of mortars. The mortar with especially fine sand performed the worst. The mortar with medium sand performed the best,especially its' properties of free shrinkage and cracking resistance.