Water transport and resistance improvement for the cementitious composites with eco-friendly powder from various concrete wastes

Abstract

The water transport properties of cementitious composites are the key parameters to evaluate the durability performance. This work gives an investigation on the impact of RP type, substitution rate and particle size on the water transport in cementitious composites, and the feasible methods of improving the water transport resistance are further investigated. Utilizing recycled paste powder (RPP), recycled mortar powder (RMP) and recycled concrete powder (RCP) produced from various concrete waste is detrimental to the hydration reaction and pore structure of cementitious composites, and the total porosity of paste incorporating 30% various RPs is 35.4–36.0% higher than that of plain paste. Utilizing RP decreases the compressive strength of cementitious composites, and a significant reduction in compressive strength occurs when RP substitution rate is 50%. The water transport in cementitious composites is increased by incorporating RP, and the RMP-prepared and RCP-prepared mortar have lower water absorption than the RPP-prepared mortar; for example, the absorption coefficient of the mortar containing 30% RPP, RMP and RCP is 72.7%, 44.9% and 48.7% greater than that of plain mortar without RP. Besides, the water transport in the mortar incorporating fine particle RP is lower than that in the mortar containing coarse particle RP. Co-mixing RP and mineral admixtures decreases the water transport in cementitious composites, and the mortar incorporating 20% RP and 10% metakaolin (or 10% silica fume) has lower water absorption and slightly higher compressive strength than plain mortar without RP.