| Summary: | 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.
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