Study On The Composition, Structure And Solidifying Properties Of Cement-Hydrated Lime-Hemihydrate Gypsum

Red clay is a kind of engineering material which exists widely in our country, and has been widely applied in engineering field, but it has some shortcomings such as the low compressive strength, the lack of water stability. So the study of the solidly red clay is of great practical and scientific significance. This article mainly studied the relationship between content and cure properties when used cement, hydrated lime and hemihydrates gypsums soil stabilizer, which provided a theoretical guidance to the practical project.The article took material structure, principle of capability and physical chemistry changes in the system synthesis process as the main lines, then researched the raw materials, synthesis process, production and capability of system. In raw materials, the article analyzed the physical mechanic of red clay, mineral compositions and micro-structure by XRD and SEM. The result show the red clay contain quartz, kaolin, elite and calcite, moreover clay content is 86%.For study of physical chemistry changes and production characteristic in the synthesis process, the article researched the effect of stabilizer (cement, hydrated lime and hemihydrates gypsums) ratio through single-doped, co-doped and tri-doped experiments. The single-doped experiment indicated that the water cure capacity and compressive strength have two kind of increasing regularity and two critical point which is 28% and 50% with various cement mixing amount, and cement take two different effects on the different of increasing regularity; when mixing hydrated lime or hemihydrates gypsum, there were a weaker cure effect. It exists the composite effect in the co-doped experiment of hydrated lime or hemihydrates gypsum and cement, and the optimum ratio of hydrated lime -mixing ratio or hemihydrates gypsum-mixing is 12.5% which determines the mixing range of cure material in the tri-doped experiment. In the cement-hydrated lime-hemihydrates gypsums phase diagram, the strength of production distributes as stripes in the air maintenance condition, but the strength decreases with cement content in the water maintenance condition, and the zone of rich gypsum' strength is minimum. Finally, the result show the strength of cure system increases quickly with sand content, and increasing speed decreases when sand content reach 30%, which provides the theoretical basis for the future experiments and practicality applications .