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.

This paper describes the behavior of geogrid–reinforced concrete members. The application of geogrids in concrete constitutes a new dimension for using geosynthetics in infrastructure. In pavement applications, geogrids have been used to provide confinement, stabilization, and reinforcement of unbound and asphalt concrete layers, as well as interlayers to mitigate reflective cracking. The ultimate objective of studying the behavior of geogrids in concrete members is to assess the feasibility and benefit of using geogrids in thin concrete overlays. The experimental program consisted of testing 21 simply supported plain and geogrid–reinforced beam specimens under four-point bending. The test parameters included three types of geogrids with different aperture shapes, physical and mechanical properties, and material composition. Additionally, two Portland cement concrete mixtures were used: normal and high strength. Results from testing confirm the reinforcing benefit of the geogrids as evidenced from the load-deflection response in terms of postpeak behavior, load capacity, crack mouth opening displacement (CMOD), and failure mode. Conclusions regarding correlations between the failure properties and the properties of the geogrid are made.

This study attempts to identify mechanical and physical properties of geogrids that are critical to their effectiveness in the stabilisation of pavement subgrade. Geogrid properties, including aperture size, wide-width tensile strength and junction strength, for four geogrid products are correlated with bench-scale interface test results, including direct shear and pull-out, and accelerated pavement testing (APT) results. APT is conducted through the use of a one-third scale APT device, the model mobile load simulator (MMLS3) on geogrid-reinforced pavement sections. The pavement sections are constructed on a subgrade soil with a low California bearing ratio. The performance of each pavement section is evaluated by measuring surface rutting at various trafficking stages. The analysis reveals a strong relationship between performance and junction and tensile strength of geogrids at small strains, whereas aperture size has a positive correlation with pull-out test results.

This paper presents the research effort in which the viscoelastoplastic continuum damage (VEPCD) model is developed and calibrated for the behavioral prediction of asphalt–aggregate mixtures subjected to tensile stresses in pavement structures. It is found that the formation of strains in the mixtures becomes highly localized as microcracks densify, coalesce, and further grow to develop into macrocracks. However, conventional linear variable differential transformers (LVDTs) used in most laboratory tests are unable to capture the localized process zone strains [or fracture process zone (FPZ) strains] due to various limitations. Consequently, the VEPCD model, calibrated using LVDT measurements, ceases to accurately predict the performance of asphalt–aggregate mixtures after the strain localization. This study explores the use of a digital image correlation (DIC) technique for measuring the FPZ strains in an aim to extend the validity of the VEPCD model beyond localization. An experimental/analytical method...

Limited investigations evaluated the synergistic effects between ceramic waste powder (CWP) and blast furnace slag (BFS) on the pozzolanic activity and thermal properties of cementitious materials. In this paper, tested binders were produced by substituting the cement by either 20% CWP, 40% BFS, or combinations of 20% CWP and 30% BFS; the physicochemical characterizations were performed at various hydration ages. Scanning electron microscopy (SEM) images showed that the calcium hydroxide crystals are particularly visible in the paste prepared with cement only, while these crystals are considerably reduced for the paste containing CWP and BFS additions. Such results were confirmed by the Frattini and strength activity index tests, reflecting the occurrence of synergistic reactions that enhanced the pozzolanic reactions and led to increased amounts of calcium silicate hydrates. Regardless of the firing temperature, mortars prepared with a ternary binder composed of cement, CWP, and BFS exhibited improved residual strength and thermal conductivity. Such data can be of particular interest to cement producers and concrete technologists seeking improved sustainability and recycling processes of CWP materials.