Geological Polymer Volume Stability And Strength Of Study

Geopolymer is a new generation of alumino-siilcates inorganic cementitious materials, whose molecular structure consists of SiO₄ and AlO₄ tetrahedra linked alternately by sharingal the oxygen. As compared to Portland cement, geopolymer possess the following merits: abundant raw materials resources, easy preparation, energy saving, no CO₂ emission, good volume stability, reasonable strength gain in a short time, ultra-excellent durability and high fire resistance and low thermal conductivity. These properties makes geopolymer a strong candidate for substituting Portland cement. In addition, in vestigation into geopolymer can also further develop and enrich the discipline of inorganic cementitious material.Test investigation on the chemical shrinkage or expansion of alkali-activated cementing materials and water-cement were carried out in this paper. The results showed that under curing temperature of 20±1℃condition, alkali-activated slag and alkali-activated fly ash cementing materials and water-cement all showed chemical shrinkage and those values grew with the increase of chemical reaction ages; of which, the chemical shrinkage values of water-cement were the biggest and that of alkali-activated slag cementing material were the smallest at the same age; alkali-activated metakaolinite cementing material showed chemical expansion and its value grew with the increase of chemical reaction ages, its reaction products were amorphous analogues of zeolites (because of having the capacity of NH₄⁺ ion exchange of zeolites), in which the reaction products with low degree of polymerization did notable contribution for the chemical expansion; the main reaction products alkali-activated slag and alkali-activated fly ash cementing materials were similar to that of water-cement, in which there also were a small amount of amorphous analogues of zeolites, this partly neutralized the chemical shrinkage. Test investigation on the change in volume of alkali-activated cementing materials and water-cement under drying and wetting conditions were carried out in this paper, in which water-cement was as control sample. The results showed that the characteristics of the change in volume of alkali-activated cementing materials under drying and wetting conditions were low bulking factor and high theirs own shrinkage and high drying shrinkage against ordinary Portland cement. It was a conclusion that the service environment of alkali-activated cementing materials will be appropriate for the moisture while not for the dry.Test investigation on the compressive streng of alkali-activated cementing materials sand and cement sand in the cycle of wet and dry conditions, three different conditions and long-term conservation of the intensity, in which cement mortar as a comparison sample in a series of pilot studies in the paper. Dry-wet cycle conditions for these different kinds of cementitious materials affect the intensity of a significant development, but alkali-activated cementing materials for the base to stimulate the impact of plastic sand is not too great. Compared with cement sand, alkali-activated cementing materials and alkali-activated fly ash cementing materials the rapid development of the hydration reaction in the test block in forming 7d strength development has been basically completed.