The normal and high strength geopolymer concretes showed similar mass loss curves, with relatively higher mass loss in the high strength geopolymer concrete. It can be seen from Fig. 13 that most of the mass loss occurred at 400 oC. The mass loss of the concretes at 400 oC was 2.5% and 4% for GPN and GPH respectively. The rate of mass loss reduced in the geopolymer concretes afterthis temperature while that of the OPC concrete continued at a similar rate until 650 oC. The mass loss of the normal strength and high strength geopolymer concrete specimens at 1000 oC were
4.3% and 4.8% respectively.