Properties of Geopolymer Paste from Fly Ash Blended with Metakaolin as Pervious Concrete

摘要

The purpose of this research was to study pervious geopolymer concrete with different amounts of pozzolan such as lignite fly ash (F), metakaolin (M) and alkali solution such as sodium silicate (Na_2SiO_3) and 8 mol/L sodium hydroxide (NaOH) solution. Constant NaOH/Na_2SiO_3 ratio of 0.5, three alkali liquid/pozzolan (L/P) ratios as e.g., 0.5, 0.6 and 0.7 and pozzolan/coarse aggregate ratio of 1:8 were used. The compressive strength of 50×50×50 mm~3 cube specimens was tested at the age of 28 days. In addition, compressive strength of 100 mm in diameter and 200 mm in height cylindrical specimens was carried out at the age of 7, 14, 21 and 28 days. The chemical compositions and microstructures of specimens were characterized by X-Ray Diffraction and Scanning Electron Microscope, respectively. The resultant mixture of FM0.7, i.e., 50%F+50%M and L/P ratio of 0.7 was the best proportion for pervious geopolymer concrete according to the compressive strength, water permeability and microstructural images. The bond of Si-O-Al and Si-O-Si characterized by Fourier Transform Infrared Spectroscope spectra confirmed the developed geopolymeric structure.