On the mechanical and shrinkage behavior of cement mortars reinforced with carbon nanotubes

This paper investigates the reinforcement efficiency of mortars produced with different types of carbon nanotubes (CNTs) in terms of their mechanical strength, ultrasonic pulse velocity, elastic modulus, fracture toughness, shrinkage and microstructure. The incorporation of 0.05-0.1% of CNTs was able to reduce the early shrinkage up to 62% and increase the flexural strength and fracture energy up to 33% and 65%, respectively. Well-dispersed CNTs could improve the post-cracking resistance of mortars, being able to effectively bridge microcracks up to around 1 μm wide. Microscopic analysis shows that CNTs can potentially improve the quality of the cement matrix in the aggregate-paste interfacial transition zone.