The effect of powder activated carbon on mechanical properties and pore structures of cement-based mortars

Abstract

Powdered activated carbon (PAC) has a well-developed micropore structure for adsorbing nitrous oxides, volatile organic chemicals (VOCs) and erosion ions in cement-based materials with the potential to improve their durability and the multi-functionality. The mechanical properties, water absorption ratio and pore structure of cement-based mortars were investigated with PAC of 0.5%, 1.0% and 2.0% by weight of cement and fly ash (FA). As PAC incorporation ratio increased, the compressive and flexural strengths of the mortars with and without FA both increased. PAC had a significant impact on the evolution of the pore structure of the cement pastes with and without fly ash, causing changes in the water absorption ratio of the mortars. As the PAC incorporation ratio increased from 0.5% to 2.0% by mass of the binders, the total porosity of the cement pastes without FA increased, but the total porosity of the FA-blended cement pastes decreased. When PAC and FA were used together in cement pates, PAC was excellently compatible with the cement matrix, dispersing well into the hardened cement pastes in 3-dimensional space. The volume fraction in the micron-scale pore structures using 3-dinmensional visualization was decreasing with an increase of the incorporation of PAC and the degree of reaction of fly ash. Therefore, PAC is an effectively porous material for improving the mechanical properties and pore structure of cement-based materials.