秸秆灰对砂浆力学性能的影响和微观分析

Effect of straw ash on mechanical properties and microscopic analysis of mortar

秸秆灰含有大量的活性SiO2,具有一定的火山灰活性,可以作为水泥掺合料使用。为了探究秸秆灰对水泥砂浆强度的影响,采用秸秆灰作为掺合料制备砂浆进行了试验分析。使用3种不同活化处理方法以提高活性,将秸秆灰按水泥质量的百分比(10%、20%和30%)等量取代水泥掺入到水泥砂浆中,分别对不同龄期砂浆进行抗压、抗折强度试验、X射线衍射(X-ray diffraction, XRD)和扫描电子显微镜(Scanning electron microscope, SEM)检测,对其力学性能和微观形貌进行了分析。结果发现,在养护前期秸秆灰会抑制砂浆强度的发展,各组砂浆强度都有不同程度的下降;在养护后期,秸秆灰砂浆强度增长速率提高,其中经过研磨、400℃高温灼烧,并水洗处理后的秸秆灰在掺量为10%时,砂浆强度效果影响明显,60 d龄期时抗压强度高于基准组,达到75 MPa,抗折强度与基准组持平,达到10.4 MPa,会略微降低砂浆的韧性。

Straw ash contains a large amount of active SiO2, which has a certain volcanic ash activity, and can be used as cement admixture. In order to explore the effect of straw ash on the strength of cement mortar, straw ash was used as admixture to prepare mortar for experimental analysis. The straw ash was used in three different activation treatments to increase the activity, and it was mixed into cement mortar in equal amounts instead of cement as a percentage of cement mass(10%, 20% and 30%). The compressive and flexural strength tests, X-ray diffraction(XRD) and Scanning electron microscopy(SEM) tests were carried out on mortars at different ages to analyze their mechanical properties and microscopic morphology. The results show that straw ash can inhibit the development of mortar strength in the early curing stage, and the mortar strength of each group is not decreased to some extent. In the late curing period, the strength growth rate of straw mortar increases. After grinding, burning at 400 ℃ and washing treatment, the straw ash has obvious influence on the mortar strength when the content is 10%. At the age of 60 days, the compressive strength is higher than that of the reference group, reaching 75 MPa, and the flexural strength is the same as that of the reference group, reaching 10.4 MPa, but the toughness of the mortar will be slightly reduced.