Laboratory Evaluation of Alkali-Activated Slag Concrete Pavement Containing Silica fume and Carbon Nanotubes

Engineers and contractors strive to find the best type of concrete pavement for use in various conditions and applications due to poor performance of asphalt pavements in different climatic conditions, rapid erosion of pavement, poor durability and change in performance characteristics during operation and being non-economic during the period of operation compared to concrete pavements, and not being consistent with the sustainable development principles due to the use of oil-based adhesives.The most common use for portland cement is in the production of concrete that has led to production of greenhouse gases, including carbon dioxide, and global warming has been one of its consequences.More attention has been paid to alkali-activated concrete pavement as a solution because of these effects.The present study has investigated the behavior of alkali-activated slag (AAS) concrete pavement containing silica fume and carbon nanotubes (CNTs).For this purpose, silica fume and CNTs were used as additive for active alkali slag concrete, respectively.The flexural strength, compressive strength, tensile strength, chloride ion charge passed and durability against freeze-thaw cycles was decreased and water penetration was increased by adding silica fume and the use of CNTs in concrete has increased flexural strength, compressive strength, tensile strength, chloride ion charge passed and durability against freeze-thaw cycles and decreased water penetration.The addition of CNTs should have an optimum amount of 5%, so that the mechanical properties and durability of concrete will be decreased by adding more of this additive.The best mix design is for alkali activated slag carbon nanotubes (AASN5) sample, the properties of flexural strength (9%), compressive strength (15%), tensile strength (15%) and chloride ion charge passed (38%) of the AASN5 sample have increased compared to AAS for 28-day curing and penetration (33%) and weight loss decreased after freezethaw cycle.