Microstructural Study of Common Concrete Manufactured in Congo-Brazzaville

Abstract

This study aims to fundamentally analyze the microstructure of concrete formulated from local materials collected in Brazzaville and Pointe-Noire, developing eight distinct concrete formulations. The objective of this work is to evaluate how the specific composition of each concrete formulation influences the porous structure, which plays a key role in the overall performance of the material, particularly its durability against environmental aggressions. The pore size, which ranges from a few tenths of an angstrom to several microns, illustrates the great microstructural diversity present in these concretes. This diversity is essential to understand, as it directly affects properties such as mechanical strength, permeability to water or chemicals, and the concrete’s ability to resist cracking or the penetration of corrosive substances. The precise distribution of these pores thus makes it possible to anticipate the behavior of the material under real conditions of use. To this end, scanning electron microscopy (SEM) was used to observe the size and distribution of pores at different scales, ranging from ×100 to ×1000. This technique offers high resolution, enabling detailed images of the microstructure to be obtained, particularly on fractured and polished samples. The study also highlights the heterogeneous spatial distribution of pores, indicating that the microstructure is not uniformly distributed throughout the sample. This heterogeneity can influence crack propagation, the diffusion of corrosive agents, or overall mechanical strength. Understanding this spatial organization is therefore crucial for the geometric reconstruction of the porous structure, enabling improved modelling and prediction of concrete durability under different conditions of use.