Effect of Carbon Nanotube and Silica Aerogel on Compressive Strength, Durability and Thermal Conductivity of Concrete

Silica aerogels as a nano material have significant properties including high porosity, high specific surface area, excellent heat insulation and low dielectric constant properties, low density and the potential to become an effective building insulation material. However, the implementation of silica aerogel as building insulation is restricted due to high manufacture in cost. Furthermore, despite having a relatively high compressive strength, it is very fragile due to its low tensile strength. In this study, carbon nanotube was used in order to overcome the undesirable properties of silica aerogel in concrete. Carbon nanotubes (CNTs) have been extensively studied as a reinforcement material for cement-based composites. The growing interest in this field comes from the desire to modify the cement matrix at the scale of their main compounds, taking advantage of the outstanding properties of CNTs. This study examined compressive strength, electrical resistivity, and penetration of chloride and thermal conductivity of concrete. To this end, 16 mix designs of concrete were considered and totally 192 samples were made. Silica aerogel was used in the amounts of 0, 4, 6, 8 percent of concrete and carbon nanotube was used in quantities of 0, 0.03, 0.05, .07 percent weight of concrete. The results showed that combination use of silica aerogel and nanotube not only improves the compressive strength and durability of concrete but also enhances the performance of thermal conductivity of concrete. Also, the optimum percent of nanotube and silica aerogel in the mix design of concrete are 5% and 4% respectively.