Anisotropy assessment and capillary absorption coefficient estimation of brick and mortar materials based on drilling resistance

The anisotropy of the capillary absorption coefficient is critical to moisture transport modeling and durability prediction, whereas reliable on-site assessment methods remain scarce. Herein, a new anisotropy index based on drilling resistance was proposed. An extruded fired-clay brick and Portland cement mortar were chosen as target materials. Leeb hardness, P-wave velocity, capillary absorption coefficient, and drilling resistance were tested and analysed in different directions. The influence of anisotropy on the capillary absorption coefficient was investigated. The results indicate that: (1) The new index effectively reflects anisotropy by comprehensively accounting for multi-directional drilling data. (2) Extrusion moulding significantly impacts clay brick anisotropy; drilling resistance shows that layered compaction yields denser mortar in lower sections, more distinct at higher water-cement ratios. (3) Multivariate regression models estimating capillary absorption coefficient with Leeb hardness, P-wave velocity, and drilling resistance have been developed. Research results can be applied to on-site investigations of buildings. • A new anisotropy index was proposed based on drilling resistance. • The extrusion moulding process significantly affects the anisotropy of clay bricks. • Multivariate regression models to assess capillary absorption coefficient were developed. • Combining the drilling resistance method with non-destructive testing techniques.