Researchers have unveiled intriguing insights about the thermal properties of sand, pointing to its potential impacts not only on construction but also on local climates. The comprehensive study, published on March 1, 2025, investigates how different types of sands—from sunny beaches to arid deserts—behave under solar radiation. The research team collected forty-three sand types from various locations, focusing on how these sands’ characteristics, such as color and composition, influence their temperature under sunlight.
The investigation found substantial correlations between factors such as sand color, solar reflectance, and temperature variations. Sands with high reflectance showed significantly lower temperatures compared to those with darker hues. “Sands with high reflectance present lower temperatures than those with low reflectance,” noted the researchers, emphasizing the direct connection between the physical properties of sand and thermal behavior.
To conduct their analysis, the researchers employed the Hot Disk method, which allows for accurate measurements of thermal conductivity and heat capacity. This setup proved effective for assessing the transient thermal properties of granular materials, efficiently documenting results without the need for large samples. After days of collecting data, particularly during sunny exposures on rooftops, they compiled temperature readings from May 22 to May 26, 2023, demonstrating the efficacy of their approach.
Among their findings, the team discovered dramatic temperature disparities between different types of sand exposed to the same solar conditions. For example, there was a remarkable temperature difference of 17.2 °C between white sand collected from Raivavae, French Polynesia, and black sand from Samoa. These variations highlight the need for careful selection of materials used in urban landscaping and construction, where heat island effects can exacerbate local climates.
Microstructural analysis provided additional depth to the findings, illustrating clear distinctions between coral sands, which exhibited porous structures, compared to denser, more compact non-coral sands. “Microstructural analysis revealed significant differences between coral and non-coral sands types, with coral sands exhibiting porous structure,” the authors noted, showcasing how these traits factor significantly not just in thermal performance but also sustainability practices.
The research contributes significantly to fields beyond environmental science, touching on aspects of urban planning, geothermal applications, and climate modeling. Understanding sand’s thermal behavior could guide planners and builders toward more energy-efficient designs and materials. The data gathered is expected to have lasting impacts on environmental studies, particularly those dealing with heat management and climate adjustments.
Another interesting observation from the study was the role of silica content on the thermal conductivity of sand. The highest thermal conductivity recorded—at 0.330 Wm−1K−1—was found among Australian sands, prompting curiosity about their unique geological origins. On the contrary, the lowest thermal conductivities were measured at 0.172 Wm−1K−1 for sands from Medjumbe Island and Raivavae, illustrating the vast differences among sand types even within similar ecosystems.
Through rigorous experimentation and extensive sample analysis, the research has opened doors to many future inquiries. It emphasizes the importance of selecting appropriate materials for urban development and reaffirms the interconnectedness of local climates with the choice of foundational materials.
Continued exploration of sand’s thermal properties can improve urban heat management strategies, inform construction practices, and influence future studies on climate resilience. This study stands as a reminder of the unrecognized impacts simple materials like sand can have when subjected to solar radiation, defining not just temperatures but the very character of our environments.