Modification of Masonry Mortar and Structure of Ceramic Bricks to Reduce Efflorescence

2019 ◽  
Vol 808 ◽  
pp. 3-8 ◽  
Author(s):  
Grigory Ivanovich Yakovlev ◽  
Iuliia Ginchitskaia ◽  
Valeriy Grahov ◽  
Grigory Nikolaevich Pervushin ◽  
Irina S. Polyanskikh ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Water Saturation ◽  
Soluble Salts ◽  
External Appearance ◽  
Sodium Salts ◽  
Multilayer Carbon Nanotubes ◽  
Salt Corrosion ◽  
Cement Mortars ◽  
Under Construction ◽  
Masonry Mortar

At present, efflorescence formation on the surface of brickwork is a problem for many buildings under construction and those already built. Efflorescence not only spoil the external appearance of the facades, but in rare cases can even lead to peeling of the brick and reducing its durability. The conducted researches show that in most cases efflorescence on the facades of buildings under construction is formed by sodium sulfate and calcium carbonate. Sources of these salts are masonry cement mortars with plasticizing additives containing sodium salts. In this case, the porous structure of bricks contributes to its water saturation and the migration of soluble salts, leading to the formation of efflorescence on the masonry surface. This article suggests the criteria for selecting mortar composition that excludes the appearance of soluble salts, and introduces results of the research on the resistance of ceramic bricks modified with multilayer carbon nanotubes to salt corrosion.

Using of Untreated Carbon Nanotubes in Cement Compositions

2016 ◽  
Vol 865 ◽  
pp. 6-11 ◽  
Author(s):  
Kateryna Pushkarova ◽  
Maryna Sukhanevych ◽  
Artur Martsikh
Keyword(s):  
Carbon Nanotubes ◽  
Cement Paste ◽  
Cementitious Materials ◽  
Positive Influence ◽  
Mechanical Tests ◽  
Strength Characteristics ◽  
Concrete Durability ◽  
Cement Mortars ◽  
Optimum Decision ◽  
Cement System

One of the most important problem of concrete durability is increasing of waterproofing. Researches are devoted studying of cement mortars modified by carbon nanotubes, dispersed in plasticizers solutions. Were investigated physico-mechanical properties of cement paste, cement-sand mortar into which structure entered untreated carbon nanotubes (production of plant TM "Spetsmash" Kyiv, Ukraine) in various quantity. Were used as plasticizers in cement compositions additives substances of the various chemical nature – naphtaleneformaldehyde, melamineformaldehyde and polycarboxylate. Quantity of untreated nanotubes varied from 0,5%; 1,0% and to 1,5%. Concentration of additives was accepted taking into account recommendations of producers and made about 1% from the weight of cement. Were studied some technological processes of introduction untreated carbon nanotubes in cement system and is shown that the way of introduction of nanomodifiers has essential impact on strength characteristics of cementitious materials. Optimum decision introduction of untreated carbon nanotubes is using its in dispersion plasticizer of the working concentration prepared in an ultrasonic dispergator is established. Results of physico-mechanical tests of cement paste and cement-sand mortar showed positive influence at introduction of untreated carbon nanotubes as cement modifiers on strength characteristics of samples. Resalts is shown that the nanomodifier, used quantity about 1% in solution of lignosulfonate with polycarboxylate and melamineformaldehyde plasticizer has great impact on strength characteristics.

Influence of carbon nanotubes on the dissipation of disturbances in a magnetic fluid layer

2021 ◽  
Vol 57 (2) ◽  
pp. 273-280
Keyword(s):  
Carbon Nanotubes ◽  
Elastic Properties ◽  
Magnetic Fluid ◽  
Fluid Layer ◽  
Viscous Friction ◽  
Multilayer Carbon Nanotubes

In this paper, processes of dissipation of disturbances of pressure and velocity in a magnetic fluid layer are experimentally studied. It is shown that the introduction of multi-layer carbon nanotubes (MCNT) up to 2wt.% into a magnetic fluid substantially increases the dissipation of disturbances due to increasing viscous friction and elastic properties of multilayer carbon nanotubes. Figs 9, Refs 9.

scholarly journals Multistage Mechanical Activation of Multilayer Carbon Nanotubes in Creation of Electric Heaters with Self-Regulating Temperature

Materials ◽  
2021 ◽  
Vol 14 (16) ◽  
pp. 4654
Author(s):  
Alexandr Viktorovich Shchegolkov ◽  
Sung-Hwan Jang ◽  
Aleksei Viktorovich Shchegolkov ◽  
Yuri Viktorovich Rodionov ◽  
Olga Anatolievna Glivenkova
Keyword(s):  
Carbon Nanotubes ◽  
Temperature Field ◽  
Mechanical Activation ◽  
Thermal Effect ◽  
Supply Voltage ◽  
Mechanical Energy ◽  
Mechanical Action ◽  
Multilayer Carbon Nanotubes ◽  
Starting Current ◽  
Paddle Mixer

The article deals with research related to the issues of nanomodification of elastomers as a basis of electric heaters with self-regulating temperature. The effect of multistage mechanical activation of multilayer carbon nanotubes (MCNTs) with graphite on the uniformity of the temperature field distribution on the surface of nanomodified organosilicon elastomer has been studied. The influence of the stages of mechanical action on the parameters of MCNTs is revealed. It has been ascertained that for the MCNTs/graphite bulk material, which has passed the stage of mechanical activation in the vortex layer apparatus, a more uniform distribution of the temperature field and an increase in temperature to 57.1 °C at the supply voltage of 100 V are typical. The distribution of the temperature field in the centrifugal paddle mixer “WF-20B” for mixing MCNTs with graphite has been investigated. It has been found that there is also a thermal effect in addition to the mechanical action on the MCNTs in the paddle mixer “WF-20B”. The thermal effect is associated with the transfer of the mechanical energy of friction of the binary mixture MCNTs/graphite on the paddle and the walls of the vessel. The multiplicity of the starting current Ip to the nominal In (Ip/In) is 5 for the first sample, 7.5 for the second sample, and 10 for the third sample at the supply voltage of 100 V. The effect of reducing the starting current and stabilizing the temperature indicates the presence of self-regulation, which is expressed in maintaining a certain level of temperature.

scholarly journals EFFECT OF CALCIUM SULFOALUMINATE ADDITIVE ON LINEAR DEFORMATION AT DIFFERENT HUMIDITY AND STRENGTH OF CEMENT MORTARS

2020 ◽  
Author(s):  
Kadhim Abdulwahid Al-Musawi ◽  
Kottayil Bindhu Abraham ◽  
Tatsiana Potses ◽  
Sergey Leonovich ◽  
Natallia Kalinouskaya ◽  
...  
Keyword(s):  
Bending Strength ◽  
High Humidity ◽  
Test Results ◽  
High Quality ◽  
Linear Deformation ◽  
Calcium Sulfoaluminate ◽  
Environmental Humidity ◽  
Cement Mortars ◽  
Under Construction ◽  
Very High

The effect of calcium sulfoaluminate additives (CSA) on the compression and bending strength of mortar, as well as linear deformation of prism samples at different environmental humidity was studied. Test results indicate that bending strength of mortars with CSA and the referent at the age of 28 days are practically equal. Compressive strength of mortars with CSA reduced by 20 ... 23% for all dosages of CSA. Relative linear deformations depend on the humidity of the environment. At a humidity of 100%, the relative linear deformations are positive and the expansion increases with increasing dosage of the expanding additive. When hardening in dry air at a humidity of 55%, the greatest shrinkage deformations were for mortars with CSA. We can conclude that the expanding effect of CSA is fully manifested at high humidity, i.e. under construction conditions, this means very high-quality moisture care for concrete structures.

Modification of Multilayer Carbon Nanotubes for the Removal of Arsenate

2016 ◽  
Vol 16 (4) ◽  
pp. 3835-3840
Author(s):  
Libing Liao ◽  
Gin-Lung Liu ◽  
Jiin-Shuh Jean ◽  
Wei-Teh Jiang ◽  
Zhaohui Li
Keyword(s):  
Carbon Nanotubes ◽  
Contact Time ◽  
Carbon Adsorbent ◽  
Superior Performance ◽  
Solution Ph ◽  
Nano Composite ◽  
X Ray ◽  
Multilayer Carbon Nanotubes ◽  
Removal Of Arsenic ◽  
Composite Carbon

The aim of this study was to explore a new nano-composite carbon adsorbent material for the removal of arsenic from water. The multilayer carbon nanotubes (MCNTs) were treated with different acids and/or modified with iron to create more surface COOH sites or Fe-impregnated MCNTs for the enhanced uptake of As(V). Tests were conducted as a function of initial As(V) concentrations, contact time, and solution pH. The coverage of ferric hydroxides on MCNTs and the uptake of As on Fe-MCNTs were independently confirmed by field emission scanning electron microscope and energy dispersive X-ray spectroscopy analyses. With an As(V) uptake capacities of 27 mg/g on Fe-MCNTs and 14 mg/g on acid-MCNTs, the material showed superior performance for As(V) removal.

Sign in / Sign up

Export Citation Format

Share Document