Micro-Mechanical and 3D Fractal Analysis, Durability, and Thermal Behaviour of Nano-Modified Cementitious Lightweight Composites for Building Facades

There are increasing research endeavours on the application of nanotechnology in the construction industry and lightweight composites. In this study, the influence of different percentage (1%, 2%, and 3% by weight of cement) colloidal nano-silica particles on the mechanical, thermal, and durability properties of lightweight cementitious composites was studied through measurement of compressive strength, flexural response, micro-hardness measurement, pore structure analysis, thermal conductivity, water permeability, and chloride penetration. Moreover, 3D X-ray Compute Tomography together with digital image analysis and 3D fractal analysis was used to characterize the nano-silica, micro-structures, and the fracture surfaces. The experimental results show that incorporating nano-silica particles resulted in a mechanical strength increase up to 45.4 % and a water permeability and chloride migration decrease up to 51.2% and 48.2%, respectively. The micro-structural and 3D fractal analysis also indicated that dense, flaw-free, and thus more resistant, interfaces to micro-cracks were formed and greater fractal dimensions were obtained with the increase of the nano-silica content. Finally, the 3D views confirmed that the nano-silica clusters were well interconnected which further increase the carrying capacity and reducing the heat flow.