Lightweight Geopolymer Made of Pumice with Various Aluminum Powder Ratios

In this work, a lightweight geopolymer was prepared using various mass proportions of extra fine aluminum powder and pumice stone that is durable to heat and sound-proof. The effect of NaOH concentration, aluminum mass ratio, the curing temperature and the curing time of the mixture on the compressive strength of the lightweight geopolymers were examined. The concentration of NaOH was found to be 2 M while the mass proportion of Na₂SiO₃/NaOH was found to be 17.5 on the lightweight geopolymers that have the highest compressive strength and the best workability in experiments. The lightweight geopolymer attained the best compressive strength with 1.6 MPa on the 28th day of curing process at 40°C. The mass proportion of aluminum used in the lightweight geopolymer was 2.5% as the density of the lightweight geopolymer obtained was 0.9 g/cm³. Their properties were examined using the Fourier transform infrared spectroscopy, X-ray diffraction, and scanning electron microscopy.