Fractal analysis of microstructures in Portland cement pastes – Effect of curing conditions

Abstract

Cement is used for the construction and renovation of structures such as buildings, bridges, and viaducts owing to its cohesive properties, low cost, versatility, and moldability. The conditions and curing time affect the microstructural characteristics and properties of cementitious materials in their various constitutions. Morphological changes occur in the microstructures of cementitious matrices with the progression of the hydration process and according to the type of cure, which affects the mechanical properties and durability of the material. Therefore, cylindrical specimens were fabricated to investigate the effect of curing conditions (ambient or submerged) on the morphology and compressive strength of hardened pastes cured for 7 and 28 days. The samples were subjected to the compressive strength test, and the surface of the fractured samples was analyzed using microscopic techniques. The quantifications of the morphological characteristics of the hydrated cement were correlated with the mechanical tests, and the local and global fractal dimensions were found to increase with time. This increase was accompanied by an increase in the compressive strength, which inhibited the propagation of the cracks and the development of broken fractal figures due to greater resistance to fracture.