Performance of cementitious mortar containing biochar -

Abstract

The construction industry, locally and globally, has witnessed significant efforts being placed on exploring new alternatives for raw materials. This has come to alleviate concerns of overexploitation of natural resources leading to their depletion, and the negative environmental impacts resulting from various practices within the construction industry. On a different note, the disposal of municipal solid waste (MSW) has also become a major concern in some countries, such as the case of Lebanon, where illegal dumping continues to have its toll on the environment. Pyrolysis has been introduced as a biomass decomposition process of MSW. It is considered as an environmentally friendly process that can mitigate open dumping. However, pyrolysis produces significant amounts of biochar as a byproduct that in turn needs to be disposed of or treated. This research aims at investigating the viability of using biochar as a sustainable alternative material for sand in construction applications, specifically, in cementitious mortar composites. Since the properties of fine aggregates are predominately responsible for the dimensional stability and durability of mortar composites, a thorough microscale physicochemical characterization of the biochar was conducted prior to its inclusion in mortar. Then, its incorporation as partial replacement of sand in mortar was assessed at the mesoscale level based on performance indices that included: compressive strength, shrinkage deformation behavior, and microstructure properties. The experimental results were used to provide guidelines and recommendations as to the optimum biochar volume fraction in mortar. Finally, findings from the study suggest that biochar based mortars yield favorable performance with regards to the durability and microstructural properties of mortar, but are less promising from a mechanical performance perspective.