Mechanical Properties and Microstructure of a Metakaolin-Based Inorganic Polymer Mortar Reinforced with Quartz Sand

The synthesis, mechanical behaviour, and microstructure of metakaolin-based geopolymer mortar reinforced with quartz sand are presented in this investigation. Fine sand (quartz sand) aggregate were added in different proportions of 50, 60, 70 or 80 wt.% to prepare the fresh metakaolin-based geopolymer paste. The geopolymer mortar was achieved by a mixture of geopolymer paste and river sand in the ratio 2:5 by mass. The mixture of sodium hydroxide solution (10 M) and sodium silicate solution (Na2SiO3) in a volume ratio of 2:3 was used as an alkaline activator. All the specimens were cured at room temperature and tested after 28 days of curing. The investigations on microstructure and physical properties indicated a significant reduction of the open pores and interconnection of micro and meso cracks in the structure network with increase in the amount of quartz sand. As a consequence, the samples show a good mechanical strength principally with the addition of 60 wt.% of quartz sand to binder with values of 8 and 66 MPa for flexural strength and compressive strength, respectively.