Abstract
In pursuing sustainability targets, the construction industry has witnessed significant efforts exerted on exploring new alternatives for raw materials. Such initiatives aim to alleviate concerns of overexploitation of natural resources leading to their depletion. 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 take its toll on the environment. Pyrolysis has been introduced as a biomass decomposition process of MSW and is considered 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 to investigate the viability of using biochar as a sustainable alternative material to sand in cementitious mortar composites. A thorough microscale physicochemical characterization of the biochar is conducted prior to its inclusion in mortar. Then, its incorporation as a partial replacement of sand in mortar is assessed at the mesoscale level, based on performance indices that included compressive strength and microstructure properties. Analysis of the experimental results are used to provide guidelines and recommendations as to the effective incorporation of biochar fraction in cementitious mortar.
Highlights
The utilization of waste by-products in construction materials as replacement of raw materials constitutes an attractive alternative to disposal and an ecofriendly solution to the challenges concerning the shortage and exploitation of non-renewable natural resources in the world
The use of biochar as a partial replacement of sand in cementitious mortar was experimentally investigated as a solution for the shortage of sand, while improving on the mechanical, physical, and microstructural properties of the bulk mortar
Biochar consists of interconnected fibers, forming a microporous cellular structure that can absorb and sustain a substantial amount of water to be used for internal curing
Summary
The utilization of waste by-products in construction materials as replacement of raw materials constitutes an attractive alternative to disposal and an ecofriendly solution to the challenges concerning the shortage and exploitation of non-renewable natural resources in the world. Extensive research has been conducted to examine several waste by-products as a potential replacement of natural sand and fine aggregates for construction. Results showed that as the incorporation volumes of coal bottom ash increased, the compressive strength remained the same as the control specimens, while the total shrinkage deformation as well as the density of mortar and concrete decreased noticeably, rendering it lightweight [4,5]. Bilir et al (2015) studied the influence of fly ash as fine aggregate in mortar by studying its effect on workability, unit weight, compressive and flexural strength, modulus of elasticity, and stress–strain behavior [6]. The study reported a decrease in compressive strength, estimated at 73.1%, and an increase in ductility, represented by the delay in crack formation due to drying shrinkage, in the presence of 100% fly ash volumes [6]
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