Geothermal pavements made of cement-reinforced clay subgrades: an ecological approach

Geothermal pavements are a sustainable alternative for meeting energy demands without exacerbating global warming. The system includes heat pumps and ground-source heat exchangers embedded in the pavement structure. This research aims to define design parameters for cement-enhanced subgrades in both cold and hot climates. Three cement-stabilized soils were modeled using a semi-wet method, compacted to 90% of modified Proctor density. A total of 81 specimens were stored at 10°C, 28°C, and 40°C. Linear regression of the results confirms that 1°C increase leads to gains of 2.7% in compressive strength, 2.5% in tensile strength, and 4.1% in resilient modules. Clay subgrades with low to medium compressibility were the most temperature-sensitive. Spatial quantification of SEM micrographs confirms that high temperatures accelerate the formation of Tobermorite and Portlandite, enhancing strength, while colder environments slow this process. The main contribution of this research is that these adjustments contribute to more sustainable geothermal pavement designs by optimizing material use based on environmental conditions. Specifically, design strategies that promote sustainability: in warm climates, cement consumption can be reduced, while in cold climates, increased pavement thickness is recommended to maintain performance. These adjustments allow more efficient and environmentally conscious geothermal pavement designs, tailored to varying temperature conditions.