Preparation and Characterization of Cementing Materials from Alkali Activated Metakaoline and Some Industrial Wastes

Abstract

Various mixes are prepared using a mixture of liquid sodium silicate and sodium hydroxide as alkaline activator solution with fixed ratio of 2.5 and the concentration of sodium hydroxide is 10 Molar. The pastes are moulded into 1 inch cubic moulds and left within the moulds at 100% relative humidity for 24 hours, then demoulded and cured under tap water for 3,7,28,56 and 90 days. The hydration characteristics of the different mixes have been tested via determination of the setting time, compressive strength, chemically combined water content, bulk density, total porosity and XRD analysis at different time, in order to study the effect of some artificial pozzolana such as ground granulate blast furnace slag (GGBFS), cement kiln by-pass dust (CKD), fly ash (FA) and calcium hydroxide on metakaolin geopolymer binders. After 28 days of curing under tap water the cubes are divided into 3 parts which used in the following curing modes: One of the hardened pastes was cured under tap water to continue hydration at the remaining time intervals. Another specimen was immersed in 5% MgSO4 solution to investigate the resistivity against sulfate attack at 3, 7, 28, 56 and 90 days. The aggressive solution was renewed monthly to maintain constant concentration. Last set of specimens were subjected to different elevated temperature 200°C, 400°C, 600°C and 800°C in an electrical furnace with a heating