LI Jiu-su, ZHANG An, BAO An-qing, CHEN Wei
In order to produce low energy consumption and low emission vegetation concrete, the geopolymer is used as cementitious material, the main influencing factors of effective porosity and compressive strength of fly ash based geopolymer vegetation concrete (FGVC) are analyzed by orthogonal test. FGVC is prepared in the laboratory, and its physical and mechanical properties are studied systematically. Activated slag-fly ash system with sodium hydroxide and sodium silicate as activators, limestone as coarse aggregate, based on the orthogonal test method, 3 factors including modulus of alkali activator, ratio of alkali-solid content to fly ash mass and slag content are selected to carry out three-factor and three-level tests, the effects of various factors on the porosity, permeability, compressive strength and pH value of pore environment of FGVC are studied when the water-binder ratio is 0.3 and the curing temperature is 65℃, then the mixture ratio with suitable effective porosity, high strength and moderate pH value is optimized. The result shows that (1) the total porosity and effective porosity of FGVC decreased when the modulus of basic activator increased from 1.0 to 1.4, and the compressive strength showed an upward trend, while the alkalinity showed a downward trend; (2) when the ratio of alkali-solid content to fly ash increased from 0.10 to 0.20, the total porosity and effective porosity of FGVC decreased first and then increased, and the compressive strength increased first and then decreased; (3) when the content of slag increased from 10% to 20%, the total porosity and effective porosity of FGVC decreased first and then increased, and the compressive strength increased first and then decreased; (4) when the modulus of alkali activator is 1.4, the ratio of alkali-solid content to fly ash is 15%, and the content of slag is 15%, the physical and mechanical properties of FGVC are the best, the water permeability is good, and the pore alkalinity of concrete is the lowest.