Performance of geopolymer concrete activated by sodium silicate and silica fume activator

Abstract

This study examined the properties (strength, workability and crack) of geopolymer concrete activated by sodium silicate and silica fume activator. Sodium silicate and sodium hydroxide (NaOH) are commonly activators used to make geological polymer composite. However, they will cause the decline of the performance of geopolymer concrete when it is prone to polymerization in the surrounding of alkaline. Silica fume can improve the workability and strength of geopolymer concrete. The Pearson correlation coefficient and experiment is used to study the performance of geopolymer concrete with sodium silicate and silica fume activator. The influence of two kinds of activators on the slump of geopolymers with different mix ratios was analyzed by Pearson correlation coefficient. The relative coefficient of mineral powder decreased from 0.785 to 0.409. The absolute relative coefficient of calcined magnesite decreased from 0.829 to 0.156. The correlation between slag, calcined magnesite and slump changed from significant to insignificant. The analysis shows that the slump of geopolymers with silica fume activator are less affected by mineral powder and calcined magnesite than that of sodium silicate activator. Geopolymer concrete have more stable performance with silica fume activator. The geopolymer concrete excited by silica fume activator compared with the sodium silicate activator, the cracks and internal porosities on the surface of the specimens are less. The compressive strength and crack of geopolymer concrete excited by silica fume activator reached 43.36 MPa and 0.095 mm, respectively, at 20 ℃ ± 2 ℃ and more than 95% humidity. It shows good early strength and less cracks. The experimental mix proportions are optimized to conduct the complex the equilibrium of physical and chemical reactions and to reinforce the mechanical property of geopolymer concrete with silicate fume activator.