Alternative Use of the Waste from Ground Olive Stones in Doping Mortar Bricks for Sustainable Façades

Abstract

The aim of achieving sustainability in construction is a reality. A useful strategy to achieve this is the use of waste from agricultural activities. This waste could reduce the environmental impacts associated with the production of raw materials such as natural aggregate, reducing energy consumption from fossil fuels and therefore CO2 emissions. This study examines the thermal conductivity of mortars doped with ground olive stones, a residual by-product of industrial processes. The objective is to evaluate the potential of ground olive stones to improve thermal insulation in construction. Ground olive stones are used as a partial replacement for the aggregates used in mortar bricks. The methodology followed herein to quantify the benefits of this product involves creating several types of mortar with a different percentage of ground olive stones in each sample (between 0% and 30%). Thermal conductivity was determined according to UNE-EN12939:2001. Finally, a case study is conducted performing an energy simulation of a residential building to determine the energy savings derived from reducing the combined thermal demands of heating and cooling and to analyse the feasibility of the alternative use of ground olive stone residue doped in mortar bricks for new sustainable façades. The results show a saving in energy demand (heating and cooling) of 0.938 kWh/m2·year when using 30% GOS-doped mortar bricks compared to the reference bricks. This is equivalent to a decrease in energy demand of 2.23% per square meter of façade. In addition, these annual energy savings are compared to the potential thermal energy created from the combustion of ground olive stones in a biomass boiler, which is the main traditional use of this waste today. It reveals that for a doping range of 5–15%, the recovery time ranges between 30 and 75 yeas, which is within the lifetime of a building. The results demonstrate the great viability of using ground olive stones as fine aggregates in mortars and their possible application in sustainable construction, in particular in more sustainable façades that allow energy savings in buildings and therefore a lower consumption of fossil, which will make it possible to reduce greenhouse gas emissions and the excessive consumption of resources.