Properties of Geopolymer Mortar Produced from Fly Ash and Rice Husk Ash: Influences of Fly Ash-Rice Husk Ash Ratio and Na2SiO3-NaOH Ratio under Curing by Microwave Energy

Abstract

This paper is to present the studied results of the influences of fly ash (FA)-rice husk ash (RHA)ratio, Na₂SiO₃/NaOH ratio under curing by microwave energy on the properties of geopolymer mortar.The FA/RHA ratios by weight at 100:0, 80:20 and 60:40 were taken into account. The parametric tests werewater requirement, setting time, and compressive strength at early-age period. Further the compressivestrengths of microwave-cured geopolymer-mortar specimens were compared to the conventional-curedones. From the test results, it was indicated that geopolymer mortar has an increase in water requirement asincreased FA/RHA ratio, while the setting times are decreased. Besides, geopolymer mortar specimens thatconsisted only of FA have the highest compressive strength under curing by conventional and microwaveenergy methods. However geopolymer mortar specimens are decreased when increased amount of RHAin the mix. Further geopolymer mortar specimens mixed with FA and RHA cured in oven at a temperaturelevel of 85 °C for 24 and 48 hours are higher than the specimens cured by microwave energy at a powerof 800 watt for 5 and 10 minutes.

Keywords : Geopolymer mortar / Fly ash / Rice husk ash / Microwave