Research On The Performance Of Fly Ash And Phosphogypsum Residue Silicate Products

The fly ash and phosphogypsum residue are both industrial byproduct. The storage of these byproducts can not only worsen the soil, pollute the environment, but also cause waste of resources. At the same time it is contrary to the idea of susutainable development. Considering the composition characteristics of fly ash and phosphogypsum residue, the subjective of this present study is to determine the feasibility of these substances being used as a kind of gelled material in the silicate products.At first, this experiment analyzes the main chemical composition and phase composition of phosphogypsum residue and the fly ash. Results show that phosphogypsum residue used in this experiment contains a certain amount of the calcium oxide and the fly ash contains large amounts of silica. Namely the raw material is suitable for the research of silicate products. Among the fly ash and phosphogypsum residue silicate products, the mechanical properties of static slurry specimens in this system is the directly standard to measure the activity of fly ash. This paper studys the affect of different factors such as dosage of fly ash, kind of stimulator, and curing method on the fly ash and phosphogypsum residue silicate products and then judges these factors’ impact on the activity of fly ash. Results of the study show that the dosage of fly ash hardly impacts strength of the static slurry specimens. And cement and sodium hydroxide both have certain excitation effect on activity of fly ash. Particularly when the cement content reaches 8% or the sodium hydroxide reaches 6%, the effect is more obvious. Besides, this study finds that using the method of heat pipe cannot continue to improve the compressive strength and flexural strength for adding exciting agent of silicate products. In addition, according to the result of this study: as to those Silicate products whic h have already added activator, the compressive or flexural strength can not be continuously increased under the condition fo high temperature curing.Based on the mechanical properties of the fly ash and phosphog ypsum residue silicate products, this paper also studys the freezing resistance and the carbonation resistance of products. Results finds that with the increase of dosage of sodium hydroxide, the freezing resistance and the carbonation resistance of the fly ash and phosphogypsum residue silicate products gradually improves. Particularly when the sodium hydroxide reaches 4%, the effect is more obvious. However the cement has little effect on enhacing he freezing resistance and the carbonation resistance of the fly ash and phosphogypsum residue silicate products. Finally, this paper analyzes the composition and microstructure of the fly ash and phosphogypsum residue silicate products. The result of this study reveals the sodium hydroxide has a more significant effect on exciting activity of fly ash relative to the cement. What is more, the formation and development of hydration products and compactness of products both gradually improve with the increase of dosage of sodium hydroxide.