Development of Geopolymer/Activated Carbon Composite Mortar from PLTU Paiton Fly Ash with the Addition of Sidoarjo Mud Waste

Cement production produces CO2 gas emissions that are harmful to the environment, so the manufacture of geopolymers can be done to substitute cement. Geopolymers are mineral chemical compounds or mixtures thereof consisting of repeating chemical units, such as silica-oxide. This research aims to make geopolymer mortar made from fly ash waste and Sidoarjo Lapindo mud composites with activated carbon to increase compressive strength, reduce moisture and increase CO2 absorption. Broadly speaking, the stages of this research began with preparing tools and materials to make geopolymer mortar, then mix design between fly ash, Sidoarjo lapindo sludge, and activated carbon with the addition of alkali activator, as well as fine aggregate in the form of Lumajang sand, which was then cured at 7, 14, and 28 days. Furthermore, characterization tests carried out for geopolymer mortar are SEM and XRD and testing compressive strength, water absorption, and CO2 absorption. The compressive strength test results showed that of all sample variations, the F100 variation had the highest compressive strength with a value of 17.57 MPa after curing for 28 days. The compressive strength of each sample variation increases with the longer curing time, except for the L100 variation. While in the additive variation group, the compressive strength of the F75C15L10 variation is the highest with a value of 17.43 MPa. In the water absorption test based on the carbon additive variation, it can be seen that the longer the curing time, the higher the water absorption.