*Review* **Recent Progress in Nanomaterials for Modern Concrete Infrastructure: Advantages and Challenges**

**Karla P. Bautista-Gutierrez 1, Agustín L. Herrera-May 1,2,\*, Jesús M. Santamaría-López 1, Antonio Honorato-Moreno <sup>1</sup> and Sergio A. Zamora-Castro 1,\***


Received: 23 August 2019; Accepted: 23 October 2019; Published: 29 October 2019

**Abstract:** Modern concrete infrastructure requires structural components with higher mechanical strength and greater durability. A solution is the addition of nanomaterials to cement-based materials, which can enhance their mechanical properties. Some such nanomaterials include nano-silica (nano-SiO2), nano-alumina (nano-Al2O3), nano-ferric oxide (nano-Fe2O3), nano-titanium oxide (nano-TiO2), carbon nanotubes (CNTs), graphene and graphene oxide. These nanomaterials can be added to cement with other reinforcement materials such as steel fibers, glass, rice hull powder and fly ash. Optimal dosages of these materials can improve the compressive, tensile and flexural strength of cement-based materials, as well as their water absorption and workability. The use of these nanomaterials can enhance the performance and life cycle of concrete infrastructures. This review presents recent researches about the main effects on performance of cement-based composites caused by the incorporation of nanomaterials. The nanomaterials could decrease the cement porosity, generating a denser interfacial transition zone. In addition, nanomaterials reinforced cement can allow the construction of high-strength concrete structures with greater durability, which will decrease the maintenance requirements or early replacement. Also, the incorporation of nano-TiO2 and CNTs in cementitious matrices can provide concrete structures with self-cleaning and self-sensing abilities. These advantages could help in the photocatalytic decomposition of pollutants and structural health monitoring of the concrete structures. The nanomaterials have a great potential for applications in smart infrastructure based on high-strength concrete structures.

**Keywords:** carbon nanotubes; cement-based materials; concrete infrastructure; graphene; graphene oxide; mechanical strength; nanomaterials; nano-Al2O3; nano-Fe2O3; nano-SiO2; nano-TiO2; smart infrastructure
