复合矿物掺合料对水泥胶砂性能和强度的影响研究

Influence of compound mineral admixtures on the properties and strength of cement mortar

以低品质粉煤灰和矿粉为主要原料,通过机械活化和化学活化双重作用,制备出一种高效复合型矿物掺合料,研究了该复合矿物掺合料对水泥胶砂工作性及强度的影响,并通过扫描电镜和压汞试验分析了复合矿物掺合料对水泥胶砂试块的微观结构的影响。试验结果表明:经机械球磨和Na_2SO_4共同活化的复合矿物掺合料(粉煤灰∶矿粉=1∶2),在内掺量达到50%时,28 d强度比空白组提高了11.3%;90 d强度比空白组提高了24.3%。通过对胶材的粒度测试发现,内掺复合矿物掺合料后,胶材的小级配(4.5～9.0μm)分布比例明显提高,从42.99%提高到62.72%,说明复掺后的复合胶凝材料变得更加致密。扫描电镜和压汞试验发现:复合矿物掺合料的掺入,使得试块的孔隙率比空白组试块降低了近一半,且在电镜下观察到其表面形貌更加致密,在微裂缝处还存在大量的"钙矾石网"状结构。

A new kind of compound mineral admixtures were prepared by mechanical milling and adding sodium sulfate to the lower quality of fly ash and mineral powder.It was ensured the adding amount of compound mineral admixtures and intensity of influence on the performance of the cement mortar,and through the scanning electron microscope and mercury injection experiments analyzed the cement mortar microscopic after internal doping compound mineral.Test results showed compound mineral admixtures(mass ratio of fly ash∶mineral powder=1∶2)after mechanical activation and sodium sulfate working together,could still improve the cement mortar strength greatly though the replacement amount reached 50%.And the intensity was 11.3%higher than the blank group in the standard curing age.The late strength(90 d age)was increased 24.3%.Because of the distribution proportion of the micellar size distribution(4.5~9.0μm)increased from 42.99%to 62.72%after adding compound mineral admixtures.On the microcosmic side,scanning electron microscopy and mercury injection test found:The porosity of cement mortar with compound mineral admixture had reduced nearly half compared with the blank group.Under the electron microscope,the surface morphology was more dense,and there was a large amount of“reticular structure of ettringite”in the microcrack.