Accelerated carbonation of one-part sodium carbonate-activated slag cements modified by calcined dolomite

Abstract

One-part or ‘just add water’ alkali-activated material is one promising option of the clinker-free cementitious material being actively researched as the alternative to traditional Portland cements for lowering the energy consumption and CO2 emission involved in the clinker production. The one-part sodium carbonate (Na2CO3)-calcined dolomite (CD)-activated slag cements were developed in this work. The CD additions were effective in shortening the setting times and meanwhile enhancing the compressive strengths of the binders. The carbonation resistance was investigated under accelerated carbonation protocols at 3.0 ± 0.2% CO2. The CD additions slowed down the kinetics of carbonation. Although the binders still underwent the pore structure degradation, the reactive CaO and MgO supplied by CD promoted the formation of calcium hemi-carboaluminate and hydrotalcite-like phase, which had the layered double hydroxide structure with the anion exchange capacity for binding the ingressive CO32− ions. Therefore, the CD addition should be recognized as a novel approach for improving the carbonation resistance of such one-part Na2CO3-activated slag material.