PERFORMANCE OF GEOPOLYMER MORTAR WITH ADDED LIME (Based on Fly Ash and Rice Husk Ash at 10M NaOH Molarity)

Abstract

Construction developments encourage the search for environmentally friendly and high-performance materials. Cement as the main material commonly used has a negative impact, namely producing carbon emissions. An alternative that can be used is to apply the use of fly ash and RHA-based geopolymer mortar with the addition of lime which functions to increase the reactive properties of class C fly ash at room temperature. This study aims to determine the performance of mortar with the addition of lime based on compressive strength, porosity, and vicat. Lime is added with several variations, namely 0.5%; 1%; 1.5%; 2%; 2.5%; 3%; 3.5%; 4% and 0% as a control. The results of the study of the addition of lime to this geopolymer mortar are to increase the compressive strength value at a certain point of 24.65 MPa (2% lime) then decrease to 13.61 MPa (4% lime), decrease the percentage of porosity with the lowest value of 7.90% (2% lime) and at a certain turning point increase by 9.37% (2.5% lime), and accelerate the setting time. The hydration process between lime and silica content forms C-S-H which will fill the pores in the test object and strengthen the mortar solids, but excess CaO interferes with the reaction, thereby reducing the strength.