Mechanical Behaviors of Metakaolin-Based Engineered Geopolymer Composite under Ambient Curing Condition

Abstract

Geopolymers have been long recognized as the next-generation building material due to environmental reasons. However, geopolymers are inherently brittle and usually require high-temperature curing. This paper was intended to develop a ductile engineered geopolymer composite (EGC) under ambient curing conditions. Two types of metakaolin powder with different particle sizes were applied as the solid precursor. The tensile, compressive, and flexural behaviors of EGC with different mix designs were investigated. It was concluded that the combinational application of coarse and fine metakaolin is conducive to the tensile and compressive behaviors of EGC materials. As the alkali concentrations increased from 6 to 14 mol/L, the tensile and compressive strength of EGC increased, whereas the tensile ductility of EGC decreased gradually. Also, the SiO2/Na2O molar ratio had negligible influence on the tensile behavior of EGC, whereas the compressive strength decreased with the increase of SiO2/Na2O molar ratios. A numerical model to predict the flexural behavior of EGC was also proposed, and the accuracy was verified with experimental results.