scholarly journals Effect of Carbon Nanotube Aqueous Dispersion Quality on Mechanical Properties of Cement Composite

2012 ◽  
Vol 2012 ◽  
pp. 1-6 ◽  
Author(s):  
Larisa I. Nasibulina ◽  
Ilya V. Anoshkin ◽  
Albert G. Nasibulin ◽  
Andrzej Cwirzen ◽  
Vesa Penttala ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Carbon Nanotube ◽  
Chemical Interaction ◽  
Mechanical Test ◽  
Aqueous Dispersion ◽  
Fold Increase ◽  
Cement Composite ◽  
Cement Matrix ◽  
Cement Pastes ◽  
Marginal Improvement

An effect of the quality of carbon nanotube (CNT) dispersions added to cement on paste mechanical properties has been studied. High-quality dispersions of few-walled CNT (FWCNTs) were produced in two steps. First, FWCNTs were functionalized in a mixture of nitric and sulfuric acids (70 wt.% and 96 wt.%, resp.) at80∘C. Second, functionalized FWCNTs were washed out by acetone to remove carboxylated carbonaceous fragments (CCFs) formed during CNT oxidation. Mechanical test results showed 2-fold increase in the compressive strength of the cement paste prepared from the dispersion of acetone-washed functionalized FWCNTs, which is believed to occur due to the chemical interaction between cement matrix and functional groups (–COOH and –OH). Utilisation of unwashed FWCNTs led to a marginal improvement of mechanical properties of the cement pastes, whereas surfactant-treated functionalized FWCNT dispersions only worsened the mechanical properties.

Effect of Carbon Nanotube on Electrical, Thermal and Mechanical Properties of Epoxy

2007 ◽  
Author(s):  
Yuanxin Zhou ◽  
Peixuan Wu ◽  
Zhongyang Cheng ◽  
Biddut Kanti Dey ◽  
Shaik Jeelani
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Carbon Nanotube ◽  
High Speed ◽  
Mechanical Test ◽  
High Vacuum ◽  
Mechanical Analysis ◽  
Thermal And Mechanical Properties ◽  
Multi Walled Carbon Nanotubes ◽  
Mechanical Agitator

In this study, electrical, thermal and mechanical properties of multi-walled carbon nanotubes (CNTs) reinforced Epon 862 epoxy have been evaluated. Firstly, 0.1 wt%, 0.2 wt%, 0.3 wt%, and 0.4 wt% CNT were infused into epoxy through a high intensity ultrasonic liquid processor and then mixed with EpiCure curing agent W using a high speed mechanical agitator. The trapped air and reaction volatiles were removed from the mixture using a high vacuum. Neat epoxy sample also was made as reference. Electrical conductivity, dynamic mechanical analysis (DMA, three point bending tests and fracture tests were performed on unfilled, CNT-filled epoxy to identify the loading effect on the properties of composites. Experimental results show significant improvement in electric conductivity. The resistivity of epoxy decreased to 15Ωm with 0.4% CNT. DMA studies revealed that filling the carbon nanotube into epoxy can produce a 90% enhancement in storage modulus and a 17° C increase in Tg, but CNT has little effect on decomposing temperature. Mechanical test results showed that modulus increased with higher CNT loading percentages, but the 0.3 wt% CNT-infusion system showed the maximum strength and fracture toughness enhancement. The decrease in strength and fracture toughness in 0.4% CNT/epoxy was attributed to poor dispersions of nanotubes in the composite.

scholarly journals PLASMA MODIFICATION OF MICROFIBERS - APPLICATION TO LIGHTWEIGHT CEMENT COMPOSITE CONTAINING RECYCLED CONCRETE

2021 ◽  
Vol 30 ◽  
pp. 7-11
Author(s):  
Jakub Ďureje ◽  
Zdeněk Prošek ◽  
Jan Trejbal ◽  
Pavel Tesárek ◽  
Štěpán Potocký
Keyword(s):  
Mechanical Properties ◽  
Composite Material ◽  
Oxygen Plasma ◽  
Cement Composite ◽  
Recycled Concrete ◽  
Plasma Modification ◽  
Cement Matrix ◽  
Foaming Agent ◽  
Cementitious Matrix

The article deals with the optimalization of composition for reinforced lightweight cement composite containing micronized recycled concrete, which will be used to produce masonry blocks. The composite material is reinforced with polypropylene microfibers. To increase the cohesion between the fibers and the cementitious matrix, the optimal modification using oxygen plasma was chosen. Furthermore, a suitable foaming agent was chosen to lighten the cement matrix. A suitable ratio of cement and micronized recycled concrete was determined. Finally, a cement composite was made from the optimized components. The mechanical properties of this composite were tested. The resulting mechanical properties of the lightweight samples were compared with the non-light samples.

scholarly journals Damping Property of a Cement-Based Material Containing Carbon Nanotube

2015 ◽  
Vol 2015 ◽  
pp. 1-7 ◽  
Author(s):  
Wei-Wen Li ◽  
Wei-Ming Ji ◽  
Yi Liu ◽  
Feng Xing ◽  
Yu-Kai Liu
Keyword(s):  
Carbon Nanotube ◽  
Cement Paste ◽  
Load Transfer ◽  
Cement Composite ◽  
Mechanical Analysis ◽  
Cement Matrix ◽  
Cement Composites ◽  
Strength Index ◽  
Damping Property ◽  
Reduction Capacity

This study aimed to explore the damping property of a cement-based material with carbon nanotube (CNT). In the study, the cement composites with different contents of CNT (0 wt%, 0.033 wt%, 0.066 wt%, and 0.1 wt%) were investigated. Logarithmic Decrement method and Dynamic Mechanical Analysis (DMA) method were utilized to study the damping property of CNT/cement composite. The influences of CNT on pore size distribution and microstructure of composite were analyzed by Mercury Intrusion Porosimetry (MIP) and Scanning Electron Microscopy (SEM), respectively. The experimental results showed that CNT/cement composite presented higher flexural strength index than that of a pure cement paste. Additional CNT could improve the vibration-reduction capacity of cement paste. Furthermore, the experiments proved that CNT could bridge adjacent hydration products and support load transfer within cement matrix, which contributed to the energy dissipation during the loading process.

scholarly journals Effect of Carbon Nanotube Size on Compressive Strengths of Nanotube Reinforced Cementitious Composites

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
Tanvir Manzur ◽  
Nur Yazdani ◽  
Md. Abul Bashar Emon
Keyword(s):  
Mechanical Properties ◽  
Carbon Nanotube ◽  
High Performance ◽  
Construction Material ◽  
High Potential ◽  
Cement Matrix ◽  
Cementitious Composites ◽  
Cement Composites ◽  
Nanoscale Science ◽  
20 Nm

Application of nanoscale science to construction material has already begun. In recent times, various nanofibers have raised the interest of researchers due to their exceptional mechanical properties and high potential to be used as reinforcement within cement matrix. Carbon nanotube (CNT) is one of the most important areas of research in the field of nanotechnology. The size and exceptional mechanical properties of CNT show their high potential to be used to produce high performance next generation cementitious composites. In this study, an attempt has been made to investigate the effect of size of CNTs on compressive strengths of CNT reinforced cement composites. Seven different sizes of multiwalled nanotubes (MWNTs) were used to produce MWNT-cement composites. A trend was observed regarding the effect of nanotube size on compressive strength of composites in most cases. MWNT with outside diameter (OD) of 20 nm or less exhibited relatively better performance. Smaller MWNT can be distributed at much finer scale and consequently filling the nanopore space within the cement matrix more efficiently. This in turn resulted in stronger composites.

scholarly journals Modification of Cement Matrix with Complex Additive Based on Chrysotyl Nanofibers and Carbon Black

2021 ◽  
Vol 11 (15) ◽  
pp. 6943
Author(s):  
Zarina Saidova ◽  
Grigory Yakovlev ◽  
Olga Smirnova ◽  
Anastasiya Gordina ◽  
Natalia Kuzmina
Keyword(s):  
Mechanical Properties ◽  
Carbon Black ◽  
Cement Composite ◽  
Particle Size Analysis ◽  
Cement Matrix ◽  
Size Analysis ◽  
Strength Increase ◽  
Fine Grained ◽  
Complex Additive ◽  
Physical And Chemical

This paper presents the results of studying the properties of cement-based composites modified with a complex additive based on chrysotile nanofibers and carbon black. The optimal composition of complex additive was stated due to the particle size analysis of suspensions with different chrysotile to carbon black ratios and the mechanical properties study of the fine-grained concrete modified with the complex additive. It was found that the addition of chrysotile in the amount of 0.05% of cement mass together with carbon black in the amount of 0.01% of cement mass leads to a 31.9% compression strength increase of cement composite and a 26.7% flexural strength increase. In order to explain the change in the mechanical properties of the material, physical and chemical testing methods were used including IR-spectral analysis, differential thermal analysis, energy dispersive X-ray analysis as well as the study of the microstructure of the samples modified with the complex additive. They revealed the formation of durable hydration products including thaumasite and calcium silicate hydrates of lower basicity that form a dense structure of cement matrix, increasing the physical and mechanical characteristics of cement-based composites.

scholarly journals Improvement of physical and mechanical properties of portland cement by introduction of prominent rocks of Uzbekistan

2020 ◽  
Vol 3 (8) ◽  
pp. 200-208
Author(s):  
Mukhiddinov Dilshod Davronovich
Keyword(s):  
Mechanical Properties ◽  
Portland Cement ◽  
Chemical Interaction ◽  
Physical And Mechanical Properties ◽  
Cement Composite ◽  
Technological Properties ◽  
Rapid Absorption ◽  
Hydrolysis Of

This article is devoted to the study of technological properties of opokoid rocks of Uzbekistan and their influence on physical and mechanical indices of Portland cement of JSC "Kizilkumcement." Accelerated hydrolysis of Portland cement minerals and their chemical interaction with additive on principle of acid-basic interaction, which leads to increased degree of compaction and structural strengthening of formed cement composite due to rapid absorption of lime and opocy rock with developed structure, are shown.

scholarly journals PERFORMANCE OF CEMENT COMPOSITES REINFORCED WITH SURFACE-MODIFIED POLYPROPYLENE MICRO- AND MACRO-FIBERS

2017 ◽  
Vol 13 ◽  
pp. 11
Author(s):  
Jakub Antoš ◽  
Lukáš Dejdar ◽  
Jan Trejbal ◽  
Zdeněk Prošek
Keyword(s):  
Mechanical Properties ◽  
Polypropylene Fiber ◽  
Image Correlation ◽  
Cement Matrix ◽  
Fiber Types ◽  
Cement Pastes ◽  
Cracking Behavior ◽  
Inductively Coupled ◽  
Four Point Bending ◽  
Surface Modified

This paper focuses on the mechanical properties investigation of cement pastes reinforced with surface treated polymer fibers. The cement matrix was composed of Portland cement (CEM I 42.5 R, w/c ratio equal to 0.4). Two polypropylene fiber types (micro- and macro-fibers) were used as randomly distributed and oriented reinforcement in volume amount of 2 %. The fibers were modified in the low-pressure inductively coupled cold oxygen plasma in order to enhance their surface interaction with the cement matrix. The investigated composite mechanical properties (load bearing capacity and response during loading) were examined indirectly by means of four-point bending mechanical destructive tests. A response of loaded samples containing treated fibers were compared to samples with reference fibers. Moreover, cracking behavior development was monitored using digital image correlation (DIC). This method enabled to record the micro-cracks system evaluation of both fiber reinforced samples.

scholarly journals Modification of the Structure and Properties of Lightweight Cement Composite with PVA Fibers

Materials ◽  
2021 ◽  
Vol 14 (20) ◽  
pp. 5983
Author(s):  
Donatas Sikarskas ◽  
Valentin Antonovič ◽  
Jurgita Malaiškienė ◽  
Renata Boris ◽  
Rimvydas Stonys ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Blended Cement ◽  
Physical And Mechanical Properties ◽  
Type A ◽  
Cement Composite ◽  
Ultrasonic Pulse Velocity ◽  
Ultrasonic Pulse ◽  
Pulse Velocity ◽  
Cement Matrix ◽  
Pva Fiber

This study addresses the application of polyvinyl alcohol (PVA) fibers to improve the performance of lightweight cement composites with pozzolans. Blended cement mixes based on expanded glass granules were modified with PVA fibers (Type A: Ø40 µm, L = 8 mm and Type B: Ø200 µm, L = 12 mm). The following research methods were used to analyse the effect of the fibers on the structure of cement matrix and physical-mechanical properties of lightweight composite: SEM, XRD, DTG, calorimetry tests, and standard test methods of physical and mechanical properties. Results from the tests showed that a denser layer of hydrates was formed around the PVA fiber and the amounts of portlandite, CSH, and CASH formed in the specimens with PVA were found to be higher. PVA fibers of Type A accelerated hydration of the cement paste, slightly increased the compressive strength of the lightweight composite, but had no significant effect on the values of density, ultrasonic pulse velocity and flexural strength. The shrinkage of cement composite was significantly reduced using both types of PVA fiber and both types of PVA fibers increased the fracture energy of lightweight cement composite with expanded granules.

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