Permeability and Abrasion Resistance of Pervious Fly Ash Lightweight Geopolymer with Lightweight Expanded Clay Aggregate (LECA) for Construction Materials

Abstract

This paper studied the permeability and abrasion resistance of fly ash based geopolymer filled with lightweight expanded clay aggregate to study for the effects of concentration of sodium hydroxide and the ratio of sodium silicate to the concentration of sodium hydroxide that affected the permeability and abrasion resistance. Dry soft clay form bored pile, collected from soil layer 2-3 meter depth, was formed into spherical-shape aggregate with 0.5 and 1.0 centimeter diameter, then fried at 1200 °C for 30 minutes. The lightweight expanded clay aggregates were mixed with sodium hydroxide solution at 10, 15, and 20 molars. Sodium silicate to sodium hydroxide ratio was about 0.67 and the ratios of alkali solvent to fly ash were 0.50, 0.55, and 0.60, respectively. The mixture was formed into cylindrical shape with further 10 centimeter diameter and 20 centimeter height, then cured in an oven at 60 °C for 48 hours, curing was carried out in plastic bag for 3, 7, 14, and 28 days, respectively. The permeability test was studied using Darcy’s Law following ASTM D 5084-90 and the abrasion resistance followed ASTM C 944-90 standard. The results showed that the concentration of solution of sodium hydroxide didn’t affect the value of permeability. For the concentration of sodium hydroxide at 10, 15 and 20 molars, it showed the permeability value in the range of 4.91-5.39 centimeter per second. Each sodium hydroxide concentration showed minimum and maximum of about 5-7 percent difference. Increasing (Na2SiO/ NaOH)/Fly ash, then decreased the permeability because the amount of fly ash was low in the geopolymer. For the study of abrasion resistance, it showed that the concentration of sodium hydroxide at 10, 12, and 20 molar didn’t affect to the percentage of the abrasion resistance. The percentages of abrasion resistance were 24.91-34.51, 25.28-33.10 and 10.29-34.42, respectively. Increasing the ratio of Na2SiO33/NaOH to the fly ash had a tendency to increase the percentage of abrasion resistance. The ratio of Na2SiO/NaOH to the fly ash equal to 0.50, gave the lowest percentage of abrasion resistance. Finally, the increase in curing reduce the abrasion.