Poultry litter ash potential as a replacement material in cementitious systems: a state-of-the-art review

Poultry litter (PL) disposal is a major concern for poultry farms around the world, it is estimated that millions of metric tons of this waste are generated globally and as consumption rates increase so does the associated waste; the usual means of disposal include soil fertilization and livestock feeding, however, these disposal strategies are linked with hazardous environmental consequences: eutrophication, ammonia (NH 3 ) emissions and leaching of heavy metals. New environmentally friendly processes have been developed in order to reduce the impact of poultry litter and provide new means of revalorization: proper management and selection, elemental recovery (P, K and N) and its use as biomass for energy generation. One of the most promising revalorization opportunities for this ash residue lies in the development of greener cementitious composites in the pursuit of net-zero energy projects by reducing the carbon footprint of the modified concrete by replacing cement or aggregates, given the typical chemical composition (> 40% CaO) of poultry litter ash (PLA). The present review deals with PLA potential to replace cement or fine aggregates in cementitious composites, how this substitution affects the transport properties of the resultant composite and the effects on strength development and future considerations to be further investigated.