Potential Use of Calcined Kaolinite-Based Wastes as Cement Replacements in Concrete - An Overview

Abstract

The use of supplementary cementitious material (SCM) to partially replace cement is a promising strategy to reduce CO2 emission and improve the overall sustainability of construction industry. Recent studies revealed that calcined clay could be used as a pozzolanic material and demonstrated an improvement in durability properties of concrete. The pozzolanic reactivity of calcined clay mainly depends on the kaolinite content due to its disordered crystal structure. They can use to replace cement at considerably high level (∼30%), and even higher (∼50%) if addition limestone powder is used. Since kaolinite is the key source of pozzolanic activity, reusing kaolinite-based waste materials could be a promising and sustainable approach instead of exploiting natural clay for calcined clay cement. This paper summarises recent published works on the use of calcined kaolinite waste as partial cement substitutions in concrete, including thermally activated coal gangue and pre-calcined clay brick and ceramic wastes which have been burnt in their fabrication process. The properties of concrete using these kaolinite-based waste materials are also discussed.