SHOULD YOU BE USING MORE PFA?

摘要

Pulverised Fuel Ash (PFA) has been used in concrete for over 50 years. It has been the subject of research for over 70 years with in excess of 10,000 papers being published. It has been shown to improve the durability of concrete by reducing chloride ingress, preventing alkali silica reaction, lowering permeability, improving sulfate resistance, preventing delayed ettringite formation, reducing water content, increasing cohesion, reducing bleeding and enhancing long term strength gain properties as well as reducing the peak concrete temperature and the environmental impact. It can replace the cement and/or the aggregates within a concrete and can even be the main constituent of the coarse aggregates, e.g. Lytag. In addition it is an economical material. It is because of the benefits, that material like High Volume Fly Ash (HVFA) concrete is gaining popularity on environmental and heat of hydration grounds. Foamed and self compacting concretes containing PFA are more stable and easier to use. Airports often use PFA concrete for runways and many road construction jobs use PFA in bridges and carriageways for both environmental and economical grounds. Precast concrete manufacturers widely use it as well as the aerated and lightweight concrete block makers. PFA has found a wide range of uses in concrete with numerous technical and environmental benefits being found. This paper will review the benefits of using PFA; will look at some of these contracts that have used PFA concrete in recent years, why they used PFA, whether it was successful, etc.