Pore structure characteristics of baking-free slag-sludge bricks and its correlations to mechanical properties

Abstract

In order to explore the relationship between the macroscopic properties and pore structure characteristics of bak-ing-free slag-sludge bricks, the compressive strength and water absorption rate using aluminum industrial slag and sludge of different substitution rates were tested. Optical instruments and image analysis software were used to measure the parameters of the pore structure. Specifically, a fractal model was built based on the fractal theory, in which the fractal dimension was used as the characteristic index of the pore structure to analyze the correlation and interaction mechanism between the fractal dimension and the macroscopic mechanical properties. Based on this study, conclusions were drawn as follows: (1) The plane pore structure of baking-free bricks shows good fractal characteristics. With the increase of the aluminum industrial slag content, the fractal dimension becomes smal-ler and the pore structure develops well; with the increase of the sludge content, the fractal dimension becomes larger and the pore structure becomes worse; (2) As the fractal dimension of the plane pore structure increases, the compressive strength of baking-free bricks falls, and the porosity and water absorption rise; (3) The optimum content of baking-free slag-sludge bricks is aluminum industrial slag 30% and sludge 10%. After 7 days of curing, baking-free bricks boast higher performance, and fully meet the performance requirements of solid concrete bricks (MU40), which can reduce time costs, and enhance enterprise revenue.