Biomass power plant has provided an alternative source of power. However, the biomass production produces enormous volume of waste especially fly ash and bottom ash. These ash materials are expensive to manage or eliminate. Experimental studies have been conducted to identify ways to reuse these waste materials, including road building. Both types of ash have similar properties to that of natural materials used in road construction as well as pozzolan, which is used to make concrete as it is an excellent binding material. However, because fly ash and bottom ash contain heavy metals and pollutants, further assessment on the environmental impact together with physiochemical characterization are more than necessary.
The research team compacted the ash materials and subjected to a series of tests including California Bearing Ratio (CBR) and Leaching. CBR test is a simple strength test that compares the bearing capacity of the material with that of a well-graded crushed stone. The testing involved applying load to a small penetration piston onto the prepared compacted ash material at a rate of 0.05 inches/minute and comparing the values obtained to the standard values obtained from testing crushed stone materials. CBR value can roughly estimate the feasibility of the materials for the intended purpose which is road construction.
Leaching test assesses the potential risk of a waste to release organic and inorganic contaminants into environment. The testing involved running water through the compacted ash materials to measure the soluble rate of waste products and proportion of dissolved components.
The results help us understand engineering properties of fly and bottom ash that may impact the environment as well as methods for utilizing these waste to build roads at a reduced cost which in turn reduce expense to eliminate them in the process.
Ms. Sutthida Boonsamran, Dr. Khamphe Phoungthong, Asst. Prof. Dr. Kuaanan Techato, and Asst. Prof. Dr. Tanan Chub-Uppakarn
Environmental Assessment and Technology for Hazardous Waste Management Research Center, Prince of Songkla University