Relationship between fracture toughness and porosity of clay brick panels used in ventilated façades: Initial investigation

• Stress intensity factor and R-curve of clay brick blocks were evaluated.
• Digital Image Analysis was used to evaluate geometry of the pore.
• Correlation between KIC and pore structure of clay brick blocks was assessed.
• An increasing in pore dimensions causes a decreasing in fracture toughness.
• An increasing in total porosity causes a decreasing in fracture toughness.

Fired clay elements are commonly used for external cladding, but the fragility of this material causes crack formation that, in conjunction with environmental actions, can even break clay brick elements. In order to optimize this technology, a relationship between fracture toughness and porosity can be helpful.In this paper, linear elastic fracture mechanics (LEFM) was applied to study the fragility of clay bricks used in ventilated façades. Stress intensity factor KIC was calculated under Mode I (opening mode) loading condition. Pore structure was evaluated by digital image analysis (DIA). We found that an increase of about 200 μm2 in pore dimension corresponds to a decrease in fracture toughness of about 24%.