Research on cement-based materials is trying to exploit the synergies that nanomaterials can provide. This paper describes the findings reported in the last decade on the improvement of these materials regarding, on the one hand, their mechanical performance and, on the other hand, the new properties they provide. In this paper, we provide a quantitative approach to the reinforcements achieved to date.
The fundamental concepts of nanoscience are introduced and the need of both sophisticated devices to identify nanostructures and techniques to disperse nanomaterials in the cement paste are also highlighted. Promising results have been obtained, but, in order to turn these advances into commercial products, technical, social and standardisation barriers should be overcome.
The main obstacle to foster the implementation of such applications worldwide is the high cost of their synthesis and dispersion techniques, especially for carbon nanotubes and graphene oxide.
The improvement of concrete properties through its interaction with admixtures has been the focus of attention since its emergence as a construction material. Apart from steel reinforcing bars, different embedded admixtures have been added to cement composites to primarily improve their mechanical performance [ 1 ]. In more recent times, nanoadmixtures have also been attracting the widespread interest of researchers due to their capability Self consolidating concrete disadvantages of human only to further improve several mechanical properties of cement-based materials, but also to provide new properties that may lead to a wide range of potential applications.
These materials include concrete, mortar and cement paste, which are used in structural elements, pavements, and finishing and repairing products [ 23 ]. In the last two decades, research on the study and manipulation of matter at the nanoscale has been expanding exponentially, supported by the advances achieved in visualising technologies, such as the atomic force microscope, scanning tunnelling microscope and focused ion beam lithography [ 4 ].
This expansion is also corroborated by the acceleration in the proliferation of scientific literature published all around the world [ 5 ], as a result of a research race between the world powers [ 6 ]. However, investments seem to partially neglect the construction sector to date, since few nanotech applications are currently in implementation.
The situation "Self consolidating concrete disadvantages of human" even more critical in the fields of sustainable construction [ 78 ] and environmental applications [ 9 ], despite the demonstrated benefits in water treatment [ 10 ], soil and water remediation [ 1112 ], self-cleaning concrete and glass surfaces, photovoltaic coatings [ 13 ], or electrochromic windows—which may potentially provide heating, cooling and lighting savings [ 14 ].
As far as the construction industry is concerned, it is obvious that this sector faces certain obstacles to "Self consolidating concrete disadvantages of human" penetration of new materials and technologies.
Within this highly fragmented industry, new knowledge is still based on empirical approaches, as construction works are long-term processes which involve high investments. In such conditions, construction companies usually avoid risks that are inherent to research and tend to be reluctant to use materials that are not specifically listed in official construction Codes [ 78 ].
Consequently, investment efforts involving nanotechnology are mostly focused on higher profit areas, such as electronics, IT information technology and health [ 1516 ]. Despite the modest resources allocated to construction research, some recent findings regarding cement matrix reinforced with nanoinclusions point to a noticeable improvement in the mechanical performance and durability of the hardened cement-matrix composite.
Additionally, it can be provided with smart features by virtue of its physical characteristics, either through its dispersion into the cement matrix or by being applied as coatings on the cement matrix surface. This paper collects the key findings regarding all the aforementioned functionalities derived from the combination of the most studied nanomaterials with the cement matrix.
Besides, it gathers the most updated information with regard to the results concerning the strengthening of the cement matrix. In order to illustrate the evolution of this field, a bibliometric study has been conducted see Figure 1.
Although relevant studies were published at the beginning of the 21st century, Figure 1 reveals that the scientific literature has significantly increased in the last decade. Therefore, the authors have mainly focused on the findings reported in this period, paying special attention to the last two years.
Number of published papers that, according to Scopus, include the terms cement and nanotechnology or nanomaterials in the title, abstract or keywords, limited to the fields of engineering and materials science. At the beginning of the research expansion of nano-modified cement composites, Sobolev et al. In their work, they paid special attention to nanoparticles and carbon nanotubes CNTsas Balaguru et al.