GEOPOLYMER SYNTHESIS FROM DEMOLISHED CONCRETE WASTES
After the earthquake on April 25, 2015 and its aftershocks a total of 4,784 public and 531,266 private buildings were either destroyed or damaged. It generated large wastes that imposed economic burden and contributed to environmental pollution. The alumino-silicate found in such wastes can be used as raw material for the synthesis of geopolymers. Geopolymers have been synthesized from construction waste such as coal fly ash (CFA) and brick dust (BD) using alkali and alkali-silicate as activators. Geopolymerization can transform a wide range of waste alumino-silicate materials into building materials with excellent chemical and physical properties such as fire, acid and earthquake resistance. A maximum compressive strength of 2.21 MPa was obtained with concrete powder treated with 6 M NaOH solution and a maximum compressive strength of 45.4 MPa was obtained with 1.0 mass ratio of Na2SiO3 to construction wastes cured for 28 days at 40°C. The compressive strength of geopolymers initially increases and then decreases with alkali concentration and varies inversely with the particle size.