粉煤灰普通砌筑干混砂浆合理配比研究

Study on the reasonable and rational proportional mixture of dry-mixed mortar with fly as for brick-making

将粉煤灰用于干混砂浆的生产，既可以解决其占地和环境污染问题，又可产生一定的经济效益。通过对阜新地区粉煤灰和其他原料的性质进行分析，以普通硅酸盐水泥、天然河砂和阜新发电厂商品粉煤灰为原材料配制干混砂浆。根据施工常用普通建筑砂浆的种类及标号，在水泥砂浆中掺人不同比率的粉煤灰。水泥取代率为15％～30％，砂浆稠度控制在7～10cm。制成标准试件后经脱模放入标准养护室养护。测定粉煤灰砂浆试件的28d抗压强度和90d抗压强度，经与标准强度进行对比，得到粉煤灰取代水泥的合理比率。结果表明，配制M5、M7．5、M10砂浆时粉煤灰的水泥取代率分别为20％、25％、20％。粉煤灰掺入砂浆中取代部分水泥后，砂浆的28d强度都超过标准强度，90．d强度则显示出更大的优越性。粉煤灰之所以可以取代部分水泥，是因为其中含有一定量的活性物质。这些活性物质与氢氧化钙、硫酸盐等反应生成了水化硅酸钙、钙矾石等物质，使凝胶体材料的整体强度，特别是后期强度得到明显提高。粉煤灰的颗粒较小，可以填充在水泥凝胶体的毛细孔中，使水泥凝胶体更加密实，进一步提高了材料的强度和抗渗性能。粉煤灰中含有大量球形玻璃体，改善了砂浆的和易性。配制的于混砂浆性能稳定，原材料种类少，便于配料加工。

This paper is inclined to present our study finding for pro- ducing the dry-mixed mortar through reasonable proportional mixture of Fry ash into the mortar. As is known, the fly ash has become a common environmental pollution, which not only takes vast useful land surface, but also bring down the quality of the local environment in the coal-mine areas. To improve the quality of the dry-mixed mor- tar, we have done a series of experiments and tests in Fuxin, Liaon- ing, by using the fly ash and other raw materials, such as the ordi- nary portland cement, the natural river sand and other raw materials needed for the purpose. According to the different types and labels of common building mortar for the construction purpose, we have tried to replace the corresponding cement with the different ratios of fly ash. The changing range of the cement substitute ratios prove to be 15 %-30% with the mortar consistency being 7 - 10 cm. In proceed- ing with our study, we have made specimens, trying to keep the stan- dard treating condition by the mold discharges. While comparing our specimens with the 28 d＇ s, 90 d＇ s compressive strength of fly ash mortar sample which was determined by the compression test and the standard strength test, we have managed to replace the cement with the fly ash in reasonable proportion. Then, we have produced the common masonry dry-mixed mortar in strict correspondence with the national standard. When we have succeeded in preparing M5, M7.5, M10 mortar, respectively, we have replaced the common ce- ment with fly ash in a ratio of 20 %, 25 %, 20 %. Through a 28 d＇ s compressive strength test, our dry-mixed mortar incorporationed into the fly ash substituting part of cement proved once again exceeding the standard strength, whereas the 90 d＇ s compressive strength test proves to be even more advantageous. Our analysis shows that the ac- tive substance in the fly ash is able to react with the calcium hydrox- ide and sulphate to form hydrated calcium silicate, ettnngite, etc, which may have positive effects on the strength of the gel material, enhancing the later strength of the gel greatly. The cement gel can be made more compact when the particles are smaller with the fly ash filled in the capillary pores of cement gel. More spherical vitreous in the fly ash helps to improve the workability of mortar remarkably. Thus, it can be said that the dry-mixed mortar made with fly ash partly in place of cement enjoys steady performance, less material species and convenient to burden processing.