A novel eco-friendly porous concrete fabricated with coal ash and geopolymeric binder: Heavy metal leaching characteristics and compressive strength

• A novel type of porous concrete made solely with industrial byproducts was developed.
• Heavy metal leaching characteristics and compressive strength were studied.
• Characteristics of geopolymer affected the diffusion of heavy metals from bottom ash.
• The porous concrete showed acceptable compressive strength and leaching behavior.

This study focuses on the development of a novel type of eco-friendly porous concrete made solely with industrial by-products. Coal bottom ash was used as a coarse aggregate and geopolymer as a binder. Experimental evaluations of heavy metal leaching behavior and compressive strength were conducted. The test results showed the concentrations of heavy metals which leached from the bottom ash in porous concrete were below the selected criteria, and the characteristics of geopolymer dominantly affect the diffusion of heavy metals from bottom ash. In addition, a significant correlation was observed among the paste thickness, measured total void ratio and compressive strength, and an empirical formula to express the relationship between the void ratio and compressive strength was derived. It is concluded that the porous concrete developed in this study can effectively immobilize heavy metals as solidified/stabilized products.