Recycling of limestone fines using Ca(OH)2- and Ba(OH)2-activated slag systems for eco-friendly concrete brick production

This study explored the possibility of using limestone fines (LF) as a supplementary material in activated slag binder systems using two types of activators (i.e., 10 wt% of Ca(OH)2 or 10 wt% of Ba(OH)2) and investigated the interactions of the activators with LF in each binder system through strength testing, powder X-ray diffraction, thermogravimetry, and mercury intrusion porosimetry. Using these binders, concrete brick samples containing LF were also made and examined for possible industrial applications. Although the influences of the LF addition on the strength, dissolution degree of the slag, reaction products, and pore-size distribution depended on the type and dosage of the activator, the addition was generally advantageous for all these aspects in both types of activations. The concrete brick made of 20 wt% LF using the Ba(OH)2 activation fulfilled the Korean standard requirements of strength and water absorption for concrete bricks, and it also satisfied the criteria of the leaching test for possible toxic elements.