Feasible Use of Biomass Bottom Ash as Addition in the Manufacture of Lightweight Recycled Concrete

Abstract

Biomass is a renewable energy source that is increasingly being used worldwide. However, because of recent increases in production, waste products from biomass combustion are becoming a relevant environmental and economic problem. Other wastes from the construction and demolition sectors have been extensively studied. For this, several research studies have been performed to study the mechanical and some durability properties in concrete manufacturing with recycled concrete and mixed aggregates from different construction origins. In previous works, the lower density of recycled mixed aggregates (RMA) and biomass bottom ash (BBA) with respect to natural aggregates was studied. This feature can be exploited for the production of construction elements that require the use of low-density materials, such as lightweight concrete. For this, the aim of this work was to study the influence of the use of recycled mixed aggregates and biomass bottom ash, as replacements for the natural aggregates, on the mechanical behaviour, durability properties and environmental risk of recycled lightweight concrete. Several replacements for natural aggregates through recycled aggregates and biomass bottom ash were applied in the manufacture of lightweight concretes. To study the concrete behaviour, properties such as density, absorption, compressive strength, flexural strength, UPV, water penetration and drying shrinkage were measured. Due to the incorporation of RMA and BBA, a decrease of the density and mechanical properties of the recycled concrete manufactured was obtained with respect to the control mix. Therefore, the results showed the possibility of applying these types of recycled materials in lightweight concretes for their application in specific constructive elements. Through this study the possibility of reuse of waste and industrial by-products (RMA and BBA) that have so far been accumulated mainly in landfill is demonstrated. The positives results show the possibility of manufacture of lightweight concrete with these by-products, achieving a material with a lower density and mechanical requirements that comply with the current standards for concrete.