Using Wastes from Thermal Power Plants for Manufacturing of Low Strength Construction Materials

Abstract

Thermal power plants (TPP) generates wastes (bottom and fly ashes) which become a serious environmental problem in Vietnam. Indeed, although in several countries fly ash can be used for cement industry, fly ash from actual TPP in Vietnam does not have enough good quality for cement production, because the fly ash treatment phase has not yet included in the generations of existing Vietnamese TPP. That is why bottom ash and fly ash purely become wastes and their evacuation is an urgent demand of the society. This paper presents an investigation using fly and bottom ashes in the manufacturing of construction materials. The aim of this study is to propose a possibility to reduce environmental impacts of fly and bottom ashes, and manufacture construction materials having low embodied energy by using less cement. Several proportions of fly ash, cement, gravel, sand and water are tried to manufacture low strength concretes which can be used for non-load-bearing walls. Specimens are tested in uniaxial compressions. Results show that with a reasonable cement amount (4–8% by weight), by replacing cement by fly ash or replacing sand by bottom ash at 10-30%, the obtained materials can be used for non-bearing materials or low strength structural materials.