This study investigates the behavior of different earth mortar compositions when exposed to elevated temperatures, considering factors such as the mineralogical nature and volumetric fraction of the aggregates used. Earth mortars made from a combination of a silty-clay earth, silica-calcareous sand and fired red ceramic bricks waste were investigated. Density, thermal conductivity, ultrasonic wave velocity, flexural and compressive strength are determined at 200°C, 400°C, 600°C and 600°C. Results show that incorporating aggregates reduces linear shrinkage and bulk density. The use of fired brick waste reduces the density, thermal conductivity and ultrasonic wave velocity. As the temperature increases up to 600°C, thermophysical properties of the mortars decrease but their compressive strength increases. At the temperature of 800°C, the mortars with silica-calcareous aggregate show a significant degradation but the addition of fired brick waste reduces the damage. TG/DSC analysis and SEM observations provided a better understanding of the reactions. The results obtained can be used to optimize the performance of earth mortars at elevated temperatures.