Experimental analysis on the effect of cavity shape on the thermal and mechanical performance of hollow concrete bricks

• The thermal and mechanical performance of concrete bricks with various cavity shapes is studied experimentally. • The thermal performance of the developed bricks was noticeable under hot ambient temperatures. • A maximum surface temperature reduction by up to 10.1 °C is attained. • Bricks with circular cavities have retained an average compressive strength of 3.65 MPa. Improving the concrete elements’ thermal performance is essential to minimise cooling loads in hot regions. However, this could be achieved using different insulation types, which are costly in most cases. This study presents an experimental investigation into how the shape of internal air cavities could influence the thermal and mechanical behaviour of hollow concrete bricks. Therefore, bricks with square, rectangular, circular, and triangular cavities were fabricated and tested, thermally and mechanically, to specify the optimal shape at three orientations (east, south and west). Thermal indicators, including the reduction in maximum surface temperature, decrement factor and temperature gradient, were analysed and deliberated. Eventually, a compressive strength test was conducted to evaluate the mechanical behaviour of the developed bricks. The research results indicated that the brick with circular cavities delivered the best thermal insulation, achieving a maximum temperature reduction by up to 10.1 °C at high ambient temperatures. Besides, this cavity shape attained compressive strength of 3.65 MPa on average, representing 9 %- 20 % higher mechanical properties than those of other cavities. These findings underscore the dual benefit of optimising air cavity geometry towards the circular shape to advance the thermal and mechanical features of concrete bricks. In addition, the research supports the production of hollow bricks that meet structural demands while significantly enhancing thermal resistance in hot climate applications.