Strength and Durability Properties of Alkali-Activated Fly Ash Earth Bricks

Abstract

AbstractThis study explores the strength and durability characteristics of alkali-activated fly ash earth bricks. Two kinds of bricks were produced, one set of bricks with the use of manufactured sand or M-sand and another set without M-sand. Alkali activator which is a combination of laboratory-grade sodium silicate and 10 M sodium hydroxide in 1:1 mass ratio is used in the study. Soil classified as clayey sand with a clay content of 14% is selected for the project. The fly ash/soil ratio and alkali activator/fly ash ratios of 0.4 and 0.6, respectively, are employed in the current study. Activator was added to the soil and M-sand and fly ash mixture and mixed thoroughly. The moist mixture was then added into the brick-making machine and compacted into bricks of size 114 mm × 102 mm × 230 mm. The bricks were subjected to ambient curing until the day of testing. Wet and dry compressive strength tests, complete saturation, flexure test, and split tensile test were conducted on the bricks. It was found that the dry compressive strength of the bricks is in the range of 8 to 10 MPa, wet compressive strength is around 70% of dry compressive strength, water absorption is around 8–12%, and split tensile strength is in the range of 0.47–0.55 MPa and with flexural strength of 0.85–1.01 MPa.KeywordsAlkali activatedFly ashM-sand