Thermal Conductivity and Volumetric Heat Capacity of Recycled Concrete Aggregates Blended with Autoclaved Aerated Concrete Grains for Road Base Materials in Vietnam

Thermal properties, such as thermal conductivity (λ) and heat capacity (Cv), are important in understanding heat transport and the urban heat island (UHI) effect. While many studies focus on surface materials rather than roadbed materials, this study targeted roadbed materials using recycled concrete aggregates mixed with autoclaved aerated concrete (AAC) grains to experimentally measure and to predict the λ and Cv under varied moisture conditions. The results showed that both λ and Cv of all tested samples increased linearly with increasing volumetric water content (θ), and the increment of AAC was effective in reducing the λ values in the whole range of θ. The addition of AAC, on the other hand, did not affect the measured Cv significantly and gave a linear increase in Cv with the increase in θ. The performance of predictive models showed that Archie’s-second-law-based model captured the measured λ values for all tested samples well by modifying the saturation exponent (n = 0.7), and the classic de Vries model predicted the measured Cv well, suggesting that Archie’s-second-law-based model would be useful to evaluate heat transport parameters for roadbed materials in this study.