Workability and mechanical property of metakaolin phosphate acid based geopolymer

Abstract

Abstract Metakaolin and different molarity of H3PO4 were used to synthesis metakaolin phosphate acid based geopolymer (PAG) at 45°C and humidity more than 98%. The fluidity of fresh PAG decreases from 15.2 mm to 13.1 mm according to the increasing molarity of H 3 PO 4 . Initial setting time and final setting time of fresh PAG increases from 21 h to 62 h and 35 h to 87 h with the molarity of H 3 PO 4 increase from 6 mol/L to 12 mol/L respectively. PAG is an early strength material, and the highest strength of PAG is 120.7 MPa at 28 day and strength at 7day is up to 90.8 MPa. Porosity decreases and pore size increases with the increasing molarity of H 3 PO 4 , Pore size between 50 nm and 100 nm is dominated in PAG. Some cracks was observed in hardened PAG.