The Morphic Effect Of Silica On Process And Hydration Products Of Hydrothermal Reaction

The properties of concrete material is decide by the raw material and the producing technology; while it can be explained from microstructure and the variety and quantity of reaction production in microcosmic aspect. Autoclaved aerated concrete, rapidly developing in the industry of construction, has become a new prevailing construction material. In one hand, it has many advantages like light mass, nice heat resistance and high level of combustion performance, etc; in another hand, a lot of industrial waste can be utilized in the new material, for example, FA, iron ore tailings and copper tailings, etc. In a word, the society in the respect of production and living will greatly benefit from autoclaved aerated concrete. But there are a great number of silicon materials whose natures change obviously with produce technology and geographic position, the research about inner common regulation of autoclaved aerated concrete is still not enough to different silicon source. This paper studies the relationship of several raw silicon material, mixture proportion and curing regime with the compression strengths and reaction results.According to the analysis of influence factors to compression strength, it turns out that the compression strengths of the production made by different materials are improved with increasing the temperature except blast-furnace slag, because anorthrite will transform to katoite in the blast-furnace slag patterns, which decrease the compression strength,and when CSH gel become the primary product in higher temperature, the compression strength of blast-furnace slag patterns will increase with temperature; In a weak curing condition when the reaction extent remain a low level, the compression strength of the samples of FA, sand and grass decrease with increasing of C/S, but the gathering action of silica fume particles make the strength of silica fume show a descending trend compared with the former; At 175℃, the relation of compression strengths and C/S show a parabola style to the patterns of FA, sand, grass and silica fume, in other words, there is a optimum C/S to compression strength, and each of them is C/SF≈0.8,C/SS≈0.55,C/SG≈0.5,C/SSi≈0.35. In the analysis of XRD, it will be found that CSH gel and CSH(B) are the common products in different patterns; and katoite can appear in a low temperature; tobermorite begin to form heavily at 175 which can be regard as a critical temp℃ erature; and it also is found the patterns of slag do not form tobermorite from beginning to end, which illustrate that an important condition to the formation of tobermorite is ample SiO2. The similar activation energy values are obtained according to means belong to the category of chemical kinetics and Jander equation that is the knowledge of solid state reaction,which demonstrates the methods using is feasible to some extent; at the meantime, the factors, effecting activation energy and obtained by anglicizing, consist of SiO2 forms, the beginning-cooling temperature and cooling rate of indefinite-form SiO2, the kind and content of impurities and particle fineness; pre-exponential factor is a function of activation energy, and the reaction rate constant can be simplified an equation only with activation energy and temperature; besides, characteristic diffusion rate which is a function of activation energy and temperature similar to reaction rate constant by kuenstlinger equation is calculated by kuenstlinger equation, and it is found that tobermorite heavily forms at the rate of 1.01×10-3~1.16×10-3(namely the critical condition). Taking the series of superficial and theoretical analysis in the paper as the basis of further research of this project, it is expected the study in deeper and wider respect can become an important fundament to research and industry of autoclaved aerated concrete.