Experimental investigation of permeability and mechanical properties of metakaolin-based mortar in relation to microstructure

Geopolymers are increasingly used as green concrete materials in many engineering structures. In this study, a series of laboratory tests is conducted to evaluate the physical, permeability and mechanical properties of a metakaolin-based geopolymer mortar (MKGM) in relation to its microstructure. The composition, preparation, and experimental procedures of the selected geopolymer specimens are first presented. The microstructure of the materials is then characterized together with the basic physical properties including fluidity, setting time, flexural and compressive strength. Gas permeability is further evaluated in relation to porosity and water saturation degree. Moreover, a series of uniaxial and triaxial tests are carried out to characterize the elastic parameters, stress-strain responses, and failure strength of MKGM specimens. The influences of confining stress on transport and mechanical properties are investigated with respect to induced cracking and pore structure change. The present study provides a comprehensive characterization of the microstructural, physical, mechanical and transport properties of the metakaolin-based mortar specimens.