Nanotechnology has brought significant innovations in science and engineering. Carbon nanotube has been considered a new and outstanding material in nanoscience field with great potential application in the construction industry. The main objective of this study is to analyze the behavior of cementitious materials produced with the insertion of carbon nanotubes of multiple walls in different concentrations and compare their physic-mechanical properties with plain mortar. This research covers the examination of nanoscale cement products and the use of carbon nanotubes to increase the strength and durability of cementitious composites. Three different ratios of carbon nanotubes have been searched: 0.20, 0.40, and 0.60%. To evaluate the mechanical properties of the samples, destructive and nondestructive tests were carried out to obtain compressive strength, tensile strength by diametrical compression, and dynamic modulus of elasticity as well as to determine their deformation properties. Methods of instrumentation such as scanning electron microscopy and porosity were also used in the analysis of microstructure of the materials. The study presents graphs, tables, and figures describing the behavior of CNT added to mortars samples, allowing a better understanding of the use of this new material in the construction industry. 1. Introduction The construction industry is a branch of engineering of great importance, providing the development of various activities for the benefit of civilization and performing significant influence on the organization of society. To cite some examples that prove this relationship between the society and the construction industry, we may think of the infrastructures of water, sewer, and transportation of a country. The activities involved in construction modify the organization of a city over time due to different architectural styles which are formed randomly as well as the distribution and use of those buildings [1]. Cement is a construction material commonly used due to its low cost and high compressive strength, and the enhancement of its performance has been a concern of the research community. Excellence effects performed by nanotechnology have allowed the development of cementitious products of low cost, high performance, and long duration, which may lead to unprecedented uses of these materials in the construction industry [2, 3]. The mechanical behavior of cementitious materials depends on structural elements and phenomena occurring in micro- and nanoscale. As a result, nanotechnology may modify the molecular structure
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