Novel hollow bricks designs as possible applications for rubber-cement mortars: preiminary mechanical, thermal, and acoustic analysis by finite element method (FEM)

Currently, the main challenges in the building industry are characterized by the maximal tendency to design and manufacture materials and elements aimed at enhancing the energy efficiency, comfort, and safety of structures. In this framework, hollow bricks have found widespread use in the construction and architectural sectors due to their versatility and enhanced lightweight, durability, and thermo-acoustic insulation properties. The mechanical, acoustic, and thermal performance of a brick can be modulated by optimizing the geometry of the internal cavity system. However, the research on functional configurations for bricks is very limited due to the restricted architectural freedom offered by traditional manufacturing techniques. The development of innovative manufacturing methods, such as 3D printing, implies considerable advantages in terms of design flexibility, allowing to prototype building units with highly complex configurations. Furthermore, to investigate the behavior of hollow bricks and perform topological optimization studies, Finite Element Method (FEM) analysis represents an advanced tool for predicting the response of a model to various type of stresses, verifying the performance and any vulnerabilities before manufacturing. In this work, innovative inner architectures based on hexagonal and fractal cavities are proposed to design novel multi-holed blocks made up of “sustainable” rubber-cement mortars. These multi-holed designs are unusual in brick technology, but their functionality (vibro-acoustic damping, strain capacity improving, heat insulation) was demonstrated in other engineering applications. To preliminary assess the influence of optimized cavity shapes on the brick’s properties, three FEM-based numerical models (mechanical, thermal, and acoustic simulations) were developed and calibrated in COMSOL Multiphysics. The output data allowed a performance analysis of the modeled bricks in terms of stress distribution, mechanical strength, thermal resistance, and sound absorption.