Cement-sand mortar is a construction material widely used; tile adhesive is one of the main applications where the compressive strength is the key performance metric. Nanoparticles like MWCNTs and HNTs are currently being used to improve the mechanical performance of the cement mortar due to their properties. The cost of MWCNTs has limited their application in the construction industry. This study focuses on the effect of two different concentrations of MWCNTs and HNTs in cement mortar; HNTs are proposed in this study to compare performance and cost overall benefits. A common problem with MWCNTs is agglomeration; to achieve a proper dispersion an ultrasonic processor was utilized. Mechanical properties of a cement mortar modified with nanoparticles were investigated with compression and bending tests on specimens performed at the age of 7 days. Results showed that concentrations of 0.1% of MWCNTs increase in compression strength by 56% and concentrations of 0.1% of HNTs performance increased by 31%, both compared to plain cement mortar.
Several experimental efforts related to the concrete improvement are focused to increase its flexural strength to complement the high compressive strength, which is usually developed by materials of this nature. The flexural strength or modulus of rupture of the concrete is important in civil engineering applications such as infrastructure projects, pavements and buildings. This work proposes an alternative to optimize concrete flexural strength through the functionalization of the 9 Angstrom (Å) Tobermorite using Carbon Nanotubes (CNT). A complete ab-initio, 3D Atomistic Model of the 9Å Tobermorite is presented as the basis of the silicate cementitious hydrated products. In order to validate the model, some mechanical properties were computed using a Density Functional Theory (DFT) based program. Afterwards, a functionalization based on CNTs with different diameters was carried out to improve the flexural strength of the concrete.
Silicon nanoparticles of 100 nm obtained by high-energy ball milling were characterized by X-ray diffraction (XRD) and transmission electronic microscopy (TEM). Results show dark areas due to a staking of defects. On the other hand, brighter areas exhibit a combination of small crystalline and amorphous zones. To fulfill and cover the micro-cracking and micro-pores generated during the welding process of 304 stainless steels joined by brazing, these nanoparticles were deposited directly in the fracture. The amorphous silicon drove the Transient Liquid Phase (TLP) at 1000°C for 20 min. This amorphous silicon decreases the energies of reaction between the substrate and melting filler. TLP increases the wettability and capillary forces between micro-cracking and micro-pores; due to that, the eutectic phase contained by the melting filler forms a liquid. Moreover, the weld beads were characterized by Scanning Electron Microscopy (SEM) to analyze the effect of silicon nanoparticles on the weld beads. These results showed that the interaction of the Si nanoparticles with metallic filler in the melting zone decreases the size and change the morphology of the present phases as well as the zone of isothermic growth.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.