Lightweight material based on fly ash geopolymer

Abstract

The utilization of fly ash in geopolymer concrete as an alternative to Ordinary Portland Cement partial replacement of cement gaining immerse importance today, mainly account of improvement in long term durability of geopolymer combined with ecological benefit. In this research, the lightweight geopolymer was produced by addition of different percentage of foaming agent and fly ash as an aluminosilicate source material to improve the geopolymer used. Mixing of fly ash and alkali activator produced aluminosilicate gel that acted as binding material for the geopolymer. Foaming agent used in this research which is aluminium powder added by percent of 0, 0.2, 0.4, 0.6 and 0.8 when mixing. Therefore, as increasing of the foaming agent, the pores formed in the geopolymer specimen then will make the density decline from 0.0203 g/cm3 to 0.0062 g/cm3 and compressive strength decrease from 9.181 MPa to 0.262 MPa. The lightweight geopolymer then were analyzed with scanning electron microscopy (SEM) which shows more pore formed larger and deeper as aluminium powder added increase. Meanwhile, fourier transform infrared spectroscopy (FTIR) to examine the functional group identification which shows the greater bonding of geopolymerization at peak range of 900 cm-1 to 1000 cm-1, where at 0% of aluminium foaming agent added is the deepest peak which shows the greater bonding strength at 962.10 cm-1.