Aggregate Made from Incinerated Sludge Residue

Abstract

Sludge is a by‐product of municipal wastewater treatment. Its disposal problems could be drastically reduced if sludge could be converted for economical uses as substitute materials. Dewatered sludge, after incineration at a high temperature, yields a hard and porous mass with low unit weight. This hardened mass of incinerated‐sludge residue can be broken down into smaller sizes that when graded in suitable proportions, manifest the basic attributes required of lightweight aggregate. When used as coarse aggregate in concrete, experimental results show that the resulting concrete satisfies the physical requirements of lightweight concrete in terms of unit weight, strength, and potential heat‐insulating properties, thus indicating that incinerated sludge residue could be a likely source of suitable lightweight aggregate. Results of the present study show that residue obtained from the incineration of dewatered sludge in a brick‐making kiln is suitable for making coarse aggregate for the production of lightweight concrete in structural as well as nonstructural applications.