Stabilised Compressed Earth Block Masonry: a mechanical behaviour analysis

Earthen construction is a vernacular building technique which adopts locally sourced geo-based materials and can provide an overall comfort of living. Despite earth being generally a weak structural material, it can offer an appealing solution for construction in terms of energy consumption, emissions and costs. Reinforcement can be introduced in earthen structures to improve mechanical response of load bearing elements, especially when subjected to horizontal forces. It is therefore of interest to study its structural behaviour. In this study, an earthen masonry system developed in Senegal for reinforced earth walls is presented. It is composed of concrete-stabilised compressed earth blocks (CEB) and earth-based mortar. The blocks are moulded with hollows which allow a minimum reinforced concrete frame to be cast in them. However, the use of concrete reinforcement in earth-based materials presents challenges not only in terms of eco-compatibility but also from a mechanical perspective. Concrete is a rigid material, whereas earth exhibits significantly lower mechanical performance. The disparity in stiffness between the two systems renders the extensive use of concrete reinforcement for earth structures incompatible. Consequently, this research investigates alternative reinforcement methods, such as Fiber Reinforced Polymers (FRP), which are compatible both ecologically and mechanically, assessing their effectiveness. Experimental tests have been carried out to identify mechanical properties of stabilised CEB and mortar (compressive strength, elastic modulus). Three masonry configurations were tested: unreinforced masonry (UM), concrete-reinforced masonry (CRM), and a mixed-reinforced masonry (MRM) system combining BFRP nets with vertical concrete elements. Experimental results demonstrated that the MRM configuration significantly improved structural performance, enhancing load resistance, stress distribution, and post-peak behaviour, while the CRM system showed mechanical incompatibility and premature failure. Additionally, a homogenised orthotropic FE model was developed and validated through experimental data to study the nonlinear response of the wall. This work provides both experimental and numerical contributions towards optimizing earthen masonry systems reinforced with composite materials, highlighting their potential for sustainable and structurally efficient construction.