Production of Water-Permeable Ceramic Bricks Derived from Fly Ash Via a Simple Pellet Method: Mechanism of Mechanical Strength and Permeability

Abstract

Rising with the sponge city construction, water-permeable bricks as emerging materials, are receiving more and more attentions. It is a beneficial way to produce water-permeable bricks using industrial solid wastes as raw materials, which could not only eliminate the adverse effect of solid wastes, but also produce sustainable products. Herein, water-permeable ceramic bricks were produced by recycling fly ash as the main material with consumption up to 80 wt% via a simple pellet method. Fly ash was firstly mixed evenly with tailings at a mass ratio of 4:1 to adjust plasticity to prepare pellets. Pellets were then pressed under low forming pressure to obtain raw bricks, which were dried and sintered at high temperature to prepare water-permeable ceramic bricks. Effects of size and water content of pellets, forming pressure, and sintering temperature on the performance of water-permeable ceramic bricks were investigated. Under optimized conditions, ceramic bricks with compressive strength of 48.6 MPa, bending strength of 6.1 MPa and water permeability of 2.83×10-2 cm/s were produced. Average pore size of optimized bricks reached 123.9 μm, which guaranteed excellent water permeability. The generated anorthite phases at high temperature contributed to the high mechanical strength of water-permeable bricks. The evaluation of heavy metal leaching toxicity indicated that the prepared bricks were environmentally-friendly. This study provides a strategy to produce water-permeable ceramic bricks derived from industrial solid wastes.

Keywords: fly ash, Water-permeable ceramic brick, Pellet method, Phase transformation, Pore structure characterization