A Geologically Inspired Low-Energy Construction Material Based on Vernacular Geomaterials for Hot and Dry Environments

Inspired by sand roses and the geological process of pressure-solution creep, this study presents a geomimetic, low-energy approach for producing sustainable bricks from vernacular geomaterials. By adapting the cold sintering technique, sand - uncalcined gypsum mixtures are densified at room temperature using minimal water and moderate pressure, thereby circumventing the high energy demands, chemical use, and substantial carbon emissions associated with conventional fired-clay or cement-based brick production. The research was conducted in two sequential experimental phases to bridge the gap between fundamental mechanism and practical manufacturability.

The first phase, conducted on small laboratory-scale samples, established the fundamental controls on mechanical performance. It demonstrated that gypsum acts as an effective binder at room temperature via a dissolution–precipitation mechanism. Critical processing parameters were identified, including gypsum content, gypsum particle size, pressure magnitude and loading mode. Notably, cyclic loading significantly enhanced the unconfined compressive strength (UCS) without requiring increases in gypsum content or applied pressure, enabling mixtures to achieve strengths comparable to or exceeding those of equidimensional concrete bricks.

The second phase focused on upscaling the process to brick-relevant dimensions. By optimizing critical parameters such as pressure duration, drying time, and ambient humidity, the study successfully produced 50 mm cubes that meet ASTM standards for load-bearing masonry (13.8 MPa). The optimized process—applying only 50 MPa of uniaxial pressure for 5 minutes, followed by one day of drying (50 °C) at controlled humidity (40 %)—yielded sand–gypsum compacts with a UCS of approximately 18 MPa. This result confirms that reduced processing times are feasible for manufacturing, provided the drying environment is carefully regulated.

Overall, this geomimetic fabrication strategy leverages locally abundant resources, drastically reduces embodied energy and water consumption, and supports circular economy principles through material recyclability. It offers a viable, sustainable alternative for construction in hot, arid climates, directly contributing to global sustainability goals.