Discussion of “Influence of salts and moisture on the thermal properties of porous building materials”

In May 2026, this journal published “Influence of salts and moisture on the thermal properties of porous building materials”, that “experimentally investigates the variation in the thermal properties of ... sintered bricks in the presence of single salts and salt mixtures across the full moisture content range from saturation to dryness”. This discussion voices concerns on this paper’s findings, starting from the implausibly small impact of moisture content on the specific heat capacity, which only increases with some 12% to 15% from dry to saturated state. Theoretical calculations, based on the rule of mixtures, infer though that the specific heat capacity should increase about 60% for clay brick and 40% for ceramic brick. Given that the paper’s transient measurement technique obtains the specific heat capacity from the measured thermal conductivity and diffusivity, however, flawed specific heat capacities automatically infer flawed thermal conductivities and/or thermal diffusivities. Accordingly, this discussion’s specific concerns on the specific heat capacity translate to general concerns on most of the paper’s outcomes.