Effects of Temperature and Fly Ash Additive on Mechanical Characteristics of Brick from Raw Water Treatment Sludge

Re-utilization of wastes in brick development has been progressively carried out and several modifications have been done to produce brick with good quality and safe. Temperature is among the factors that control the mechanical properties of brick. Therefore, the objective of this study was to investigate the effects of temperature and fly ash on mechanical properties of brick from raw water treatment sludge (RAM). Two types of brick samples were prepared included brick with 100% of RAM (RAM100) and brick from mixture of 80% of RAM and 20% AT (RAM80). Both samples were treated with different firing temperatures (unfired, 500 degrees C, 700 degrees C) for 3 h. Leaching test was also conducted to identify the concentration of the present heavy metals in the brick. The mechanical characteristic of linear shrinkage showed an increasing trend with the increase in temperature. The presence of AT increased the value of linear shrinkage compared to brick with RAM base (RRAM100) as the temperatures were increased from 350 to 700 degrees C. The density of both bricks also decreased with increasing temperature, however, increased back at higher temperature (700 degrees C). Both bricks showed increased in water absorption with increased temperatures. Presence of AT also decreased the value of water absorption when compared with RAM100 brick. The compressive strength of brick increased with increasing temperature and RAM100 brick showed apparently higher percentage than RAM80 brick. Role of AT also significantly increased the percentage of compressive strength compared to that brick of RAM100. Based on the results of leaching tests and mechanical characteristics, the raw water treatment sludge and fly ash are potentially re-utilized as base material in development of brick and several modifications are required to achieve the regulated standard as alternative construction material.