scholarly journals Influence of Dispersing Method on the Quality of Nano-Admixtures Homogenization in Cement Matrix

Materials ◽  
2020 ◽  
Vol 13 (21) ◽  
pp. 4865
Author(s):  
Elżbieta Horszczaruk ◽  
Paweł Łukowski ◽  
Cyprian Seul
Keyword(s):  
High Speed ◽  
Mechanical Performance ◽  
Chemical Properties ◽  
Cement Composite ◽  
Cement Matrix ◽  
Cement Composites ◽  
Nano Sio2 ◽  
Mechanical Stirring ◽  
Physico Chemical ◽  
Nano Fe3o4

In recent years, a nano-modification of the cement composites allowed to develop a number of new materials. The use of even small amount of nano-admixture makes possible not only to improve the physico-mechanical properties of the cement materials, but also to obtain the composite with high usability, optimised for the given application. The basic problem of nano-modification of the cement composites remains the effectiveness of dispersing the nanomaterials inside the cement matrix. This paper deals with the effect of the type and size of the nanoparticles on the tendency to their agglomeration in the cement matrix. The main techniques and methods of dispersing the nanomaterials are presented. It has been demonstrated, on the basis of the results of testing of three nanomodifiers of 0D type (nano-SiO2, nano-Fe3O4 and nano-Pb3O4), how the structure and properties of the nanomaterial affect the behaviour of the particles when dissolving in the mixing water and applying a superplasticiser. The nanoparticles had similar size of about 100 nm but different physico-chemical properties. The methods of dispersing covered the use of high-speed mechanical stirring and ultrasonication. The influence of the method of nano-modifier dispersing on the mechanical performance of the cement composite has been presented on the basis of the results of testing the cement mortars modified with 3% admixture of nano-SiO2.

scholarly journals Reuse of Heat Resistant Glass Cullet in Cement Composites Subjected to Thermal Load

Materials ◽  
2020 ◽  
Vol 13 (19) ◽  
pp. 4434
Author(s):  
Aleksandra Powęzka ◽  
Jacek Szulej ◽  
Paweł Ogrodnik
Keyword(s):  
Compressive Strength ◽  
Chemical Properties ◽  
Cement Composite ◽  
Cement Composites ◽  
Thermal And Mechanical Properties ◽  
Glass Cullet ◽  
X Ray ◽  
Average Value ◽  
Heat Resistant ◽  
Physico Chemical

The article describes the possibility of using waste glass cullet as an alternative aggregate for the production of cement composites. Three concrete mixes based on Portland cement CEM I 42.5 R with different contents of recyclate were designed. Borosilicate glass cullet was introduced into the batch by reducing the content of natural aggregate by 0%, 2.5% and 7.5%. Apparent density, water absorption and compressive strength at elevated temperature were measured. The temperature distribution, in cubic samples, was followed by thermocouples. The elements were heated in a special furnace at the temperatures of 200 °C, 400 °C, 600 °C and 800 °C. The composite topography and phase composition were observed using X-ray energy scattering electron microscopy. The results show that the appropriate modification of the cement composite with 2.5% heat-resistant glass cullet improves both the thermal and mechanical properties. Compressive strength reaches an average value of 48.6 MPa after 28 days. The increase in temperature weakens the structure of the composite. It was found that the obtained cement composite has good physico–chemical properties. The research results are presented in the article.

Numerical-Experimental Assessment of the Arumã Fiber as Reinforcement to the Cementitious Matrix

2014 ◽  
Vol 600 ◽  
pp. 460-468
Author(s):  
Maria Gorett dos Santos Marques ◽  
João de Almeida Melo Filho ◽  
Julio Cesar Molina ◽  
Romildo Dias Toledo Filho ◽  
Raimundo Pereira de Vasconcelos ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Mechanical Performance ◽  
Experimental Tests ◽  
Cement Composite ◽  
Cement Matrix ◽  
Cement Composites ◽  
Experimental Assessment ◽  
Bending Tests ◽  
The Family ◽  
The Matrix

Composites of high mechanical performance reinforced by fibers need a well set arrangement of them in the matrix so that under reinforcement which they can be submitted, a desirable performance can be shown. Thus, the cement composite studied has a cement matrix which received a reinforcement made by arumã fibers, shaped in bidirectional frames distributed in three layers. Arumã is a typical plant from the Amazon, species from the genus Ischnosiphon polyphyllus, part of the family Marantaceae. This study had the purpose of assessing the cement composites mechanical behaviour from the bending tests in four points and puncture tests in sheets which were supported by the four edges. Having presented mechanical results, a numerical simulation was made through the SAP2000 NonLinear® software, with the aim to obtain a numerical computational model able to represent the composites behaviour up to the point where the loading reaches the greatest amount. The numerical results present a good correlation with those obtained in the experimental tests.

scholarly journals Controllable synthesis of pomelo peel-based aerogel and its application in adsorption of oil/organic pollutants

2019 ◽  
Vol 6 (2) ◽  
pp. 181823 ◽  
Author(s):  
Guangyu Shi ◽  
Yizhu Qian ◽  
Fengzhi Tan ◽  
Weijie Cai ◽  
Yuan Li ◽  
...  
Keyword(s):  
High Speed ◽  
Chemical Properties ◽  
Absorption Capacity ◽  
High Porosity ◽  
X Ray Diffraction ◽  
Water Separation ◽  
Physico Chemical ◽  
Wide Range ◽  
Oil Water Separation ◽  
Oil Water

Oil/water separation is a field of high significance as it might efficiently resolve the contamination of industrial oily wastewater and other oil/water pollution. In this paper, an environmentally-friendly hydrophobic aerogel with high porosity and low density was successfully synthesized with renewable pomelo peels (PPs) as precursors. Typically, a series of sponge aerogels (HPSA-0, HPSA-1 and HPSA-2) were facilely prepared via high-speed dispersion, freeze-drying and silanization with methyltrimethoxysilane. Indeed, the physical properties of aerogel such as density and pore diameter could be tailored by different additives (filter paper fibre and polyvinyl alcohol). Hence, their physico-chemical properties including internal morphology and chemical structure were characterized in detail by Fourier transform infrared, Brunauer–Emmett–Teller, X-ray diffraction, scanning electron microscope, Thermal gravimetric analyzer (TG) etc. Moreover, the adsorption capacity was further determined and the results revealed that the PP-based aerogels presented excellent adsorption performance for a wide range of oil products and/or organic solvents (crude oil 49.8 g g −1 , soya bean oil 62.3 g g −1 , chloroform 71.3 g g −1 etc.). The corresponding cyclic tests showed the absorption capacity decreased slightly from 94.66% to 93.82% after 10 consecutive cycles, indicating a high recyclability.

Microstructural Study of Cement Composites Produced by Hazardous Waste Stabilization/Solidification

2012 ◽  
Vol 587 ◽  
pp. 97-101
Author(s):  
Bozena Vacenovska ◽  
Rostislav Drochytka ◽  
Vit Cerný
Keyword(s):  
Fly Ash ◽  
Hazardous Waste ◽  
Cement Composite ◽  
Cement Matrix ◽  
Main Task ◽  
Cement Composites ◽  
Microstructural Study ◽  
Waste Stabilization ◽  
Electron Microscopy Analysis ◽  
Microscopy Analysis

This paper deals with the chosen hazardous waste solidification/stabilisation (S/S) under the catalogue code 190811 using cement matrix with addition of classic fly ash and fluid fly ash as secondary raw binders. The main task of the research works was a microstructural study of the most successful S/S formula that will be used for development of new reclamation material. The S/S process product was subject to X-Ray analysis and to the electron microscopy analysis two years after its production to evaluate the possibility of degradation of the cement composite and releasing the contaminants into environment.

scholarly journals Vegetable fiber as reinforcing elements for cement based composite in housing applications – a Brazilian experience

2018 ◽  
Vol 149 ◽  
pp. 01007 ◽  
Author(s):  
Viviane da Costa Correia ◽  
Sergio Francisco Santos ◽  
Holmer Savastano
Keyword(s):  
Mechanical Behavior ◽  
High Performance ◽  
Mechanical Performance ◽  
Raw Materials ◽  
Cement Composite ◽  
Nanofibrillated Cellulose ◽  
Cementitious Materials ◽  
Modulus Of Rupture ◽  
Cement Matrix ◽  
Suitable Alternative

Vegetable fibers are a hierarchical structure material in the macro, micro and nanometric scales that have been used as reinforcement in cementitious materials. In nanoscale, the nanofibrillated cellulose has the advantage of having good mechanical performance and high specific surface, which contributes to improve the adhesion between fiber and matrix. In hybrid reinforcement, with micro and nanofibers, nanofibrillated cellulose forms bonding with the matrix and acts as stress transfer bridges in the nano-cracking with corresponding strengthening of the cementitious composite. Processing has a strong influence on performance of the fiber cement composite. Two fabrication methods were evaluated: (i) slurry dewatering followed by pressing and (ii) extrusion. The extrusion process strongly depends on the rheological characteristics of the fresh cement material but it can better organize the microstructure of the fiber cement due to the partial orientation of the fibers in the extruder direction. Curing process also plays a key role in the performance of the final product. Accelerated carbonation at early age is a promising technology and a strategy to mitigate the durability problems with the composite materials; it decreases porosity, promotes a higher density in the interface guarantying a good fiber–matrix adhesion and a better mechanical behavior. Alternative MgO-SiO2 clinker free binder is also presented as a suitable alternative to cementitious products reinforced with cellulosic pulps. Finally, mechanical behavior of fiber cement under flexural loading is evaluated by modulus of rupture, fracture toughness, the initial crack growth resistance in cement matrix, and fracture energy that is obtained to evaluate the influence of toughening mechanisms promoted by fibers, such as pullout and bridging, on the mechanical performance of the composites. Degradation during the service life is also crucial for the evaluation of the durability of the resulting materials and components in real applications exposed to different environmental conditions as roofing, partitioning or ceiling elements. It can be concluded that more sustainable and high performance components based on engineered natural raw materials for civil construction can bring valuable contributions for the affordable housing in particular to developing region.

scholarly journals Production, Characterization, and Evaluation of Pellets from Rice Harvest Residues

Energies ◽  
2020 ◽  
Vol 13 (2) ◽  
pp. 479 ◽  
Author(s):  
Cristina Moliner ◽  
Alberto Lagazzo ◽  
Barbara Bosio ◽  
Rodolfo Botter ◽  
Elisabetta Arato
Keyword(s):  
Moisture Content ◽  
Rice Straw ◽  
Rice Husk ◽  
Mechanical Performance ◽  
Chemical Properties ◽  
Quality Standards ◽  
Operational Conditions ◽  
Diametral Compression ◽  
Physical Chemical ◽  
Physico Chemical

Pellets from residues from rice harvest (i.e., straw and husk) were produced and their main properties were evaluated. Firstly, rice straw pellets were produced at lab scale at varying operational conditions (i.e., load compression and wt % of feeding moisture content) to evaluate their suitability for palletization. Successively, rice straw and husk pellets were commercially produced. All the samples were characterized in terms of their main physical, chemical, and physico-chemical properties. In addition, axial/diametral compression and durability tests were performed to assess their mechanical performance. All the analyzed properties were compared with the established quality standards for non-woody pellets. In general, rice straw pellets presented suitable properties for their use as pelletized fuels. Rice husk pellets fell out of the standards in recommended size or durability and thus preliminary treatments might be required prior their use as fuels.

Influence of Silica Based Carbon Nano Tube Composites in Concrete

2017 ◽  
Vol 26 (1) ◽  
pp. 096369351702600
Author(s):  
BLP Dheeraj Swamy ◽  
Vaibhav Raghavan ◽  
K Srinivas ◽  
K Narasinga Rao ◽  
Mahadevan Lakshmanan ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Carbon Nanotubes ◽  
Mechanical Performance ◽  
Cement Mortar ◽  
Cement Composite ◽  
Small Scale ◽  
Cement Composites ◽  
Potential Candidate ◽  
Carbon Nano Tube ◽  
Portland Cement Paste

This study focuses on the utilization of highly densified materials in cementitious composites with objectives of improving the mechanical performance and minimizing the number and size of defects. Due to their excellent mechanical properties, carbon nanotubes (CNTs) are now viewed as potential candidate for reinforcement in cement composites. The present paper reports the use of carbon nanotubes (CNTs) as reinforcement to improve the mechanical properties of portland cement paste and creating multifunctional concrete. In order to increase the bonding, and strength, a material with intermediate fineness, highly densified silica fumes, was also utilized. The densified silica fumes along with CNT are added to cement mortar in various proportions. Small-scale specimens were prepared to measure the mechanical properties as a function of nanotube concentration and distribution. Furthermore, properties like shrinkage, permeability and alkalinity of the resultant composite were also investigated. The study addresses the significance of CNT as an additive to the enhancement of properties of cement composite.

Research Progress on Carbon Nanotubes Reinforced Cement-Based Materials

2014 ◽  
Vol 629-630 ◽  
pp. 487-493
Author(s):  
Bao Min Wang ◽  
Shuai Liu ◽  
Yu Han
Keyword(s):  
Carbon Nanotubes ◽  
High Performance ◽  
Weight Fraction ◽  
Research Field ◽  
Research Progress ◽  
Cement Matrix ◽  
Cement Composites ◽  
Mechanical Stirring ◽  
Cement Based Materials ◽  
Reinforced Cement

For their remarkable properties, carbon nanotubes (CNTs) are considered as promising candidate for next generation of high performance and functional cement-based composites in 21st century. The paper focuses on the dispersibility, mechanical property, durability, conductivity and piezoresistivity properties of CNTs reinforced cement-based materials. A homogenous CNTs-suspension was obtained using the method which combined ultrasonic processing with mechanical stirring, electric-field introduction and surfactant decoration. The low weight fraction of CNTs improved the mechanical properties of CNTs/cement composites. The compressive strength and toughness were correspondingly improved. The added CNTs improved the sulfate attack resistance and impermeability properties of the prepared CNTs/cement mixes. Meanwhile, the added CNTs improved the pressure-sensitive, conductivity and electromagnetic absorption properties of the prepared mixes, which laid a foundation of multi-functional concrete and structure. It concludes that the key issue for CNTs/cement composites is the dispersibility and the compatibility of CNTs in cement matrix. The solving solutions are put forward. In the meantime, the further research prospects in this research field are forecasted.

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.

Micro/Nano Indentation and Micro-FTIR Spectroscopy Study of Weathering of Coated Engineering Thermoplastics

2005 ◽  
Vol 875 ◽  
Author(s):  
Samik Gupta ◽  
Jan Lohmeijer ◽  
Savio Sebastian ◽  
Nisha Preschilla ◽  
Amit Biswas
Keyword(s):  
Ftir Spectroscopy ◽  
Performance Prediction ◽  
Mechanical Performance ◽  
Coating Layer ◽  
Chemical Properties ◽  
Depth Sensing ◽  
Nano Indentation ◽  
Physico Chemical ◽  
Spectroscopy Studies ◽  
Micro Indentation

AbstractA novel combination of depth-sensing nano-indentation, micro-indentation and micro-FTIR techniques is employed towards understanding the durability of coating layers used on engineering thermoplastics upon exposure to harsh weathering environments. This combination of techniques enables study of changes in surface-to-bulk properties in the clearcoat-substrate system upon weathering; typically observed as a degradation starting from the surface and then proceeding inwards to the bulk of the material. Nano-indentation measurements carried out to understand the mechanical properties of the coating layer provide insights into the changes in hardness and modulus upon prolonged weathering exposure. Depth-sensing micro-indentation and micro-FTIR spectroscopy studies performed to evaluate mechanical performance and chemical changes, respectively, explain the influence of the substrate on the coating layer, especially at the interface upon weathering. This unique combination of depth-sensing indentation and micro-FTIR spectroscopy has led to an understanding of the properties of the coating layer and the substrate individually as well as an integral system as a function of weathering exposure time. Finally, the physico-chemical properties of the coating and substrate are linked to performance prediction, enabling optimization of coating-substrate combinations.

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