Influence of water to solid ratio on mechanical properties of GBFS-based geopolymer foam concrete

The development of sustainable building materials with reduced environmental footprint in both manufacturing and operational phases of the material lifecycle is attracting increased interest in the construction industry worldwide. A recent innovation, geopolymer foam concrete, combines theperformance benefits and operational energy savings achievable through the use of lightweight foam concrete, with the cradle-to-gate emissions reductions obtained through the use of a geopolymer binder derived from GBFS (granulated blast-furnace slag). Inthis study mechanical properties of GBFS-based foam concrete were investigated for samples of different water to solid ratio (0.252, 0.287 and 0.321). According to ASTM C 796-97 both mass of the foaming solution and water in sodium silicate solution was considered as part of the total mixing water. As a solid part GBFS and solid part of activators (NaOH and sodium silicate) was considered. A group of specimens (40x40x160 beams and 100x100x100 cubes) have been prepared and volume density, bending and compressive strength test have been performed. In a result an optimized lightweight GBFS-based geopolymer foam concrete was obtained, It is characterized by 1.8 kg/dm3 volume density, 2.6 MPa bending strength and 51.8 MPa compressive strength measured on beams and 44.1 MPa compressive strength on cubes.