Abstract
Future structures based on cement-based composite materials must be more versatile, durable, and strong in addition to being environmentally friendly and sustainable. With the introduction of nanomaterials, it is possible to improve their compressive strength, flexural strength, tensile strength, elastic modulus, toughness, heat of hydration, thermoelectric conversion efficiency, thermoelectric figure of merit, power factor, Seebeck coefficient, electrical conductivity, piezoelectric coefficient, defect reduction and cracks, and reduction of liquid and gas permeation, among others. This chapter aims to review the multifunctional contributions that nanomaterials such as carbon nanotubes (CNTs), graphene, graphene oxide (GO), reduced graphene oxide (rGO), MXenes, titanium dioxide or titania, silicon dioxide or silica, lithium carbonate, calcium carbonate, and perovskite oxides are making in the improvement of cement-based composite materials. Without a doubt, this research topic will continue to drive technological and scientific innovation in the construction industry in this century.
TopIntroduction
The social and economic growth of countries is associated with the development of civil infrastructure such as road networks, tunnels, bridges, dams, etc. that they have achieved (Irfan, 2021). To achieve this infrastructure, it is necessary to have materials based on concrete and cement because they are easy to build, economical, robust, can acquire complex geometries, and have excellent mechanical properties (Alvi, 2023). These materials have high compressive strength and quasi-brittle behavior, but to be used in infrastructure projects they require steel reinforcements to achieve tensile and flexural strength. Unfortunately, traditional concrete presents a set of limitations, design, and construction practices as well as severe exposure conditions that cause the deterioration of cementitious composite materials, which can result in aesthetic, functional, or structural problems that must be resolved but not on a volumetric scale. These structures are subject to degrading environments during operation and service that cannot be avoided such as sulfates, ice thawing, pressure or thermal differentials, CO2 penetration, chlorine and/or acids, loading during service, and impact, as summarized in Figure 1. The effect of these environments produces microcracks that produce localized weakening and over time micro defects are produced that will reduce the integrity of the elements of the structures, compromising their original mechanical properties. To minimize maintenance and extend the service life of infrastructure built using cement-based composites, structural health monitoring (SHM) is necessary (Zhang, 2024). This monitoring must provide real-time information on the condition of structures using sensing schemes based on shape memory alloys, piezoelectric materials, optical fibers, or strain gauges, which are not necessarily compatible with cementitious materials. Traditional set cement presents porosity, unhydrated cement particles, crystals, and hydrated products (Metaxa, 2021). Through nanomaterials such as MXenes, graphene, carbon nanofibers (CNFs), graphene oxide (GO), hexagonal boron nitride (h-BN), and carbon nanotubes (CNTs), it is possible to develop self-sensing cement-based materials (Liu, 2020; Luo, 2023). The main challenge of using these fillers is to distribute them homogeneously throughout the volume of the material, giving them piezoresistive properties and doing so economically while retaining the mechanical properties. To achieve these properties using nanomaterials, it is necessary to embed them in polymeric materials to be exploited in cement-based composite materials. The use of polymeric materials in cementitious matrices lies in reusing waste polymers and changing properties such as moisture absorption, brittleness, toughness, fatigue, and density (Wang, 2022). Among the polymers most used to improve the performance of cementitious matrices are rubber, polyurethane resins, furan resins, epoxy resins, methyl methacrylate, unsaturated polyester resins, and urea-formaldehyde resins. The incorporation of polymers into cementitious matrices due to their viscoelasticity increases the toughness and reduces the fragility of the composite material obtained at a volumetric level (Irfan, 2021).
Figure 1. Main environmental factors that degrade cementitious composite materials
Key Terms in this Chapter
Graphene: Two-dimensional monolayer material formed by carbon atoms packed in a honeycomb structure with excellent mechanical, electronic, and thermal properties.
Nanomaterial: Material with one or more of its dimensions in nanometers with unique physical and chemical properties.
Surfactants: Chemical compounds that decrease the interfacial tension or surface tension between a liquid and a solid, a liquid and a gas, or two liquids, and these operate as dispersants, foaming agents, wetting agents, detergents, or emulsifiers.
Graphene Oxide (GO): Material based on a simple monolayer of carbon obtained by oxidized graphite with oxygen-containing functionalities.
Cement-Based Composite Materials: Hardened material based on a cement paste obtained by hydrating cement, water, and ceramic, metallic, and polymeric materials used as reinforcements.
Mxenes: Two-dimensional inorganic material with layers of thickness of a few atoms containing transition metal carbides, nitrides, or carbonitrides.
Reduced Graphene Oxide (rGO): Material based on a simple monolayer of carbon obtained by chemically treating graphene that contains residual oxygen, heteroatoms, and structural defects.
Plasticizer: Substance or material based on mineral or chemical mixtures that are added to concrete to reduce its water requirements, improve its strength and workability, as well as to soften it.
Carbonate: Salt used to produce ceramic materials obtained by the reaction of a metal with carbon dioxide containing the anion CO 3 2- .
Oxides: Materials obtained by oxidizing elements of the periodic table with unique magnetic, mechanical, thermal, electrical, optical, and electrochemical properties.