Study of the Compressive Strength and Thermal Behaviour of Lightweight Concrete in Cameroon

This thesis contributes to sustainable innovation in construction materials. The primary objective is to evaluate the balance between mechanical strength, thermal behavior, and structural lightness, with the goal of identifying formulations best suited to energy-efficient and environmentally friendly building applications. To this end, several lightweight concrete mixtures were developed by partially replacing conventional aggregates with natural lightweight ones (pozzolan and PKS) used independently. The Dreux-Gorise method guided the mix design, and a cement fixed dosage of CPJ 42.5 was adopted. Cylindrical specimens (16×32 cm) were cast and subjected to standardized tests to assess fresh and dry density, compressive strength, porosity, and thermal behavior. The experimental results showed a clear relationship between the type of lightweight aggregate and the overall concrete with 34% PKS achieving a dry density of 1850 kg/m3 and a compressive strength of 19.3 MPa at 28 days, while the formulation with 23% demonstrated a superior compressive strength of 24 MPa at 28 days, with a density of 2100 kg/m3. In addition to experimental testing, a digital validation of the compressive strength was conducted exclusively through numerical simulations performed in ANSYS, using literature-based values of thermal conductivity, specific heat capacity, and density consistent with the concrete formulations developed in this study. The simulation aimed to analyze transient heat transfer and to highlight the thermal insulation potential of lightweight concrete. This research provides a comparative insight into two rarely juxtaposed natural aggregates and reinforces the role of digital methods in evaluating the thermal performance of materials.