Drying kinetics and moisture diffusivity in fired clay bricks under varying hygrothermal conditions

Moisture loss from masonry façades can lead to cumulative drying shrinkage and cracking, affecting the long-term serviceability and durability of buildings. This study evaluates the drying behaviour of commonly adopted Fired Clay Brick from free saturation to ultimate equilibrium under controlled temperature–relative humidity environments. Unlike previous studies, the test sample has been collected at a regional scale to establish reliable practice benchmarks for FCB. Experimental data obtained from laboratory tests have been used to quantify key moisture transport characteristics, including constant drying rate, convective mass transfer coefficient, drying curves and non-linear moisture diffusivity. The results show that the drying behaviour generally follows standard patterns, except at 90% RH, where surface condensation restricts moisture loss. Constant drying rate values display clear correlations with variations in temperature and RH, and the empirical model coefficients used to predict drying curves have been successfully linked to drying temperatures at three different RH levels. Inverse analysis further reveals that non-linear moisture diffusivity increases as RH decreases. The generated dataset provides a robust foundation for accurate hygrothermal modelling and simulation of masonry structures in the National Capital Region of India.