Microstructural Analysis of Cement Stabilized Compressed Earth Blocks That Incorporate Recycled Glass Sand and the Crushed Concrete Fraction of Construction and Demolition Wastes

Human activities significantly influence the risk levels of natural disasters, with the construction industry contributing heavily to waste production and resource depletion as the global population grows and housing demand rises. This research seeks to mitigate some of these impacts. To reduce the demand for natural aggregates, compressed earth blocks (CEBs) were formulated using recycled waste materials—specifically crushed concrete and glass sand—stabilized with cement. The resulting blocks exhibited physical, mechanical, and thermal properties that position them as viable candidates for construction purposes. Investigating the microstructure of these masonry units and its correlation with their macroscopic properties provides the technical foundation necessary for the building industry to adopt them in sustainable architecture for hot and humid climates. Methodologies including thermogravimetric analysis (TGA), scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), and SEM image analysis (SEM-IA) demonstrated strong correlations across the 12 formulations (four matrices at three cement concentrations each). For instance, matrices with 15% cement by weight—which achieved compressive strengths between 6.2 and 7.3 MPa—showed greater mass loss associated with intralayer water and hydration products, a reduction in both porosity and the interfacial transition zone (ITZ), and higher concentrations of silica and calcium.