scholarly journals The Effect of Fiber Geometry and Interfacial Properties on the Elastic Properties of Cementitious Nanocomposite Material

2015 ◽  
Vol 2015 ◽  
pp. 1-14 ◽  
Author(s):  
Ala G. Abu Taqa ◽  
Rashid K. Abu Al-Rub ◽  
Ahmed Senouci ◽  
Nasser Al-Nuaimi ◽  
Khaldoon A. Bani-Hani
Keyword(s):  
Elastic Modulus ◽  
Cement Paste ◽  
Parametric Study ◽  
3D Model ◽  
3D Models ◽  
Cement Matrix ◽  
Fiber Waviness ◽  
Axisymmetric Model ◽  
Three Phase ◽  
Reinforced Cement

This paper investigates the elastic (Young’s) modulus of carbon Nanotube- (CNT-) reinforced cement paste using 3D and axisymmetric models using Abaqus software. The behavior of the CNT and the cement matrix was assumed to be fully elastic while the cohesive surface framework was used to model the interface. To investigate the effect of fiber waviness on the value of the elastic modulus, 3D models were developed assuming different distributions of fibers. The results obtained using the 3D model were compared to those obtained using the simplified three-phase axisymmetric model which consists of one single CNT aligned in the center of composite unit cell, an interface, and cement matrix. A parametric study was then carried out using the axisymmetric model to study the role of the interface in the composite elastic modulus without accounting for the presence of the interfacial transition zone (ITZ or interphase). The results showed that the CNTs waviness significantly reduced their reinforcing capability in the cement paste. On the other hand, the results obtained using the axisymmetric model were found to be in good agreement with those obtained using the 3D model. Moreover, the results of the parametric study showed that the interface properties significantly affect the composite elastic modulus and alter its behavior.

Nanomechanical Performance of Interfacial Transition Zone in Fiber Reinforced Cement Matrix

2018 ◽  
Vol 760 ◽  
pp. 251-256 ◽  
Author(s):  
Vojtěch Zacharda ◽  
Petr Štemberk ◽  
Jiří Němeček
Keyword(s):  
Elastic Modulus ◽  
Transition Zone ◽  
Cement Paste ◽  
Steel Fiber ◽  
Mechanical Performance ◽  
Creep Compliance ◽  
Interfacial Transition Zone ◽  
Cement Matrix ◽  
Average Value ◽  
Reinforced Cement

This paper shows a micromechanical study of interfacial transition zone (ITZ) around steel fiber in cement paste. It investigates microstructure and mechanical performance of the ITZ by a combination of nanoindentation and scanning electron microscopy (SEM). The investigated specimens were made from cement CEM I 42.5R paste with dispersed reinforcement in the form of steel fiber TriTreg 50 mm. The SEM demonstrated larger porosity and smaller portion of clinkers in the ITZ. Nanoindentation delivered values of elastic modulus, hardness and creep parameters around the fiber. An average value of elastic modulus in ITZ was at the level of 67% in comparison with cement bulk and the width of ITZ was about 40 µm. The value of hardness was found to be 60% of the average hardness of the bulk cement paste. The measured load-displacement curves were used for calculation of creep indentation parameter (CIT) and the creep compliance function. An average value of the creep compliance in the ITZ was found to be two times higher than in the cement bulk.

scholarly journals The Effect of Interfacial Transition Zone Properties on the Elastic Properties of Cementitious Nanocomposite Materials

2015 ◽  
Vol 2015 ◽  
pp. 1-13
Author(s):  
Ala G. Abu Taqa ◽  
Rashid K. Abu Al-Rub ◽  
Ahmed Senouci ◽  
Nasser Al-Nuaimi ◽  
Khaldoon A. Bani-Hani
Keyword(s):  
Mechanical Properties ◽  
Composite Material ◽  
Elastic Modulus ◽  
Transition Zone ◽  
Parametric Study ◽  
Nanocomposite Materials ◽  
Interfacial Transition Zone ◽  
Cement Matrix ◽  
Reinforced Cement ◽  
Cohesive Surface

A parametric study was conducted to explore the effect of the interfacial transition zone (ITZ or interphase) on the overall elastic modulus of the CNT-reinforced cement. The effect of the ITZ properties on the elastic modulus of the CNT-reinforced cement was investigated using a four-phase axisymmetric model consisting of a single CNT aligned at the center of composite unit cell, an interface, an ITZ (or interphase), and a cement matrix. The CNT and cement matrix were assumed fully elastic while the interface was modeled using a cohesive surface framework. The width and mechanical properties of the ITZ and the interface were found to affect significantly the elastic modulus and the behavior of the composite material.

Cement as a thermoelectric material

2000 ◽  
Vol 15 (12) ◽  
pp. 2844-2848 ◽  
Author(s):  
Sihai Wen ◽  
D. D. L. Chung
Keyword(s):  
Thermoelectric Power ◽  
Cement Paste ◽  
Carbon Fibers ◽  
Cement Matrix ◽  
Electron Conduction ◽  
Cement Pastes ◽  
Hole Conduction ◽  
Reinforced Cement ◽  
The Absolute ◽  
Short Carbon

Cement pastes containing short steel fibers, which contribute to electron conduction, exhibit positive values (up to 68 μV/°C) of the absolute thermoelectric power. Cement pastes containing short carbon fibers, which contribute to hole conduction while the cement matrix contributes to electron conduction, exhibit negative or slightly positive values of the absolute thermoelectric power. The hole and electron contributions in carbon fiber reinforced cement paste are equal at the percolation threshold. Addition of either steel or carbon fibers to cement paste yields more reversibility and linearity in the variation of the Seebeck voltage with temperature difference (up to 65 °C).

scholarly journals Development and analysis of sponge gourd (Luffa cylindrica L.) fiber-reinforced cement composites

BioResources ◽  
2019 ◽  
Vol 14 (4) ◽  
pp. 9981-9993
Author(s):  
Victor A. Querido ◽  
José Roberto M. d’Almeida ◽  
Flávio A. Silva
Keyword(s):  
Cement Paste ◽  
Natural Fiber ◽  
Vascular System ◽  
Cement Matrix ◽  
Cement Composites ◽  
Fiber Reinforced ◽  
Luffa Cylindrica ◽  
3D Network ◽  
Sponge Gourd ◽  
Reinforced Cement

Sponge gourd (Luffa cylindrica L.) fiber-reinforced cement composites were developed and analyzed. Dried sponge gourd fruit’s fibrous vascular system forms a natural 3D network that can reinforce matrices in composite materials, diverting cracks along the complex array of 3D interfaces between the fibers and the cementitious matrix. To avoid fiber deterioration, the cement paste was modified by incorporating pozzolanic materials. The fibers were mechanically characterized by tensile testing of strips of the 3D natural fiber array and of single fibers extracted from the array. The fibers had an average tensile strength of 140 MPa and an average Young’s modulus up to 28 GPa. Image analysis showed that the fiber spatial distribution inside the 3D network was random. The modified cement paste was characterized by its workability (flow table test) and mechanical behavior (compression and three-point bending tests), with average results of 430 mm, 62.7 MPa, and 6.2 MPa, respectively. Under bending, the cement matrix collapsed after the first crack. The sponge gourd-cement composite manufactured with 1 wt% of fibers showed an average flexural strength of 9.2 MPa (approximately 50% greater than the unreinforced matrix). Importantly, the composite also presented a limited deflection-hardening behavior. These results support sponge gourd’s possible use as reinforcement in cement matrix composites.

SIMULATION OF PULSATILE BLOOD FLOW THROUGH STENOTIC ARTERY CONSIDERING DIFFERENT BLOOD RHEOLOGIES: COMPARISON OF 3D AND 2D-AXISYMMETRIC MODELS

2013 ◽  
Vol 25 (02) ◽  
pp. 1350023 ◽  
Author(s):  
Safoora Karimi ◽  
Mitra Dadvar ◽  
Mahsa Dabagh ◽  
Payman Jalali ◽  
Hamid Modarress ◽  
...  
Keyword(s):  
Blood Flow ◽  
Carotid Artery ◽  
3D Model ◽  
Flow Behavior ◽  
Three Dimensional ◽  
3D Models ◽  
Secondary Flows ◽  
Pulsatile Blood Flow ◽  
Axisymmetric Model ◽  
Symptomatic Carotid

Hemodynamic factors such as velocity distribution, pressure gradient and wall shear stress are thought to play an important role in the prognosis of symptomatic carotid occlusion. Although there are many studies about modeling the blood flow behavior in carotid, hemodynamic characteristics of blood flow in a stenosed carotid artery is still debatable. In this study a three-dimensional (3D) model of a symmetric stenosed common carotid artery (CCA) is developed and the simulation results of it are compared to the experimental data where subsequent agreement is confirmed. To study the accuracy of two-dimensional (2D) axisymmetric model, the result of it is compared to the result of the 3D model. Two non-Newtonian rheological models, namely Carreau and modified Power-law, as well as Newtonian model are used to realize the hemodynamical differences of 2D-axisymmetric and 3D models in pulsatile blood flow. Comparing the 3D simulated results with 2D-axisymmetric modeling results that were published in recent years indicates that the assumption of 2D-axisymmetric model cannot adequately predict the velocity profiles even for a symmetric stenotic artery. Although a symmetric stenotic artery is considered, the results indicate a nonsymmetric flow in poststenosis region that is detected by the presence of extensive secondary flows particularly at diastole. The existence of secondary flows that can only be detected in 3D modeling is the main reason for the differences in hemodynamic factors in 3D and 2D results.

scholarly journals UNDERWATER PHOTOGRAMMETRY DIGITAL SURFACE MODEL (DSM) OF THE SUBMERGED SITE OF THE ANCIENT LIGHTHOUSE NEAR QAITBAY FORT IN ALEXANDRIA, EGYPT

2019 ◽  
Vol XLII-2/W10 ◽  
pp. 1-8 ◽  
Author(s):  
M. Abdelaziz ◽  
M. Elsayed
Keyword(s):  
3D Model ◽  
Low Cost ◽  
Data Gathering ◽  
Archaeological Site ◽  
3D Models ◽  
Surface Model ◽  
Digital Surface Model ◽  
Architectural Elements ◽  
3D Photogrammetry ◽  
First Time

<p><strong>Abstract.</strong> Underwater photogrammetry in archaeology in Egypt is a completely new experience applied for the first time on the submerged archaeological site of the lighthouse of Alexandria situated on the eastern extremity of the ancient island of Pharos at the foot of Qaitbay Fort at a depth of 2 to 9 metres. In 2009/2010, the CEAlex launched a 3D photogrammetry data-gathering programme for the virtual reassembly of broken artefacts. In 2013 and the beginning of 2014, with the support of the Honor Frost Foundation, methods were developed and refined to acquire manual photographic data of the entire underwater site of Qaitbay using a DSLR camera, simple and low cost materials to obtain a digital surface model (DSM) of the submerged site of the lighthouse, and also to create 3D models of the objects themselves, such as statues, bases of statues and architectural elements. In this paper we present the methodology used for underwater data acquisition, data processing and modelling in order to generate a DSM of the submerged site of Alexandria’s ancient lighthouse. Until 2016, only about 7200&amp;thinsp;m<sup>2</sup> of the submerged site, which exceeds more than 13000&amp;thinsp;m<sup>2</sup>, was covered. One of our main objectives in this project is to georeference the site since this would allow for a very precise 3D model and for correcting the orientation of the site as regards the real-world space.</p>

scholarly journals FROM ARCHIVE DOCUMENTATION TO ONLINE 3D MODEL VISUALIZATION OF NO LONGER EXISTING STRUCTURES: THE TURIN 1911 PROJECT

2020 ◽  
Vol XLIII-B2-2020 ◽  
pp. 837-844
Author(s):  
D. Einaudi ◽  
A. Spreafico ◽  
F. Chiabrando ◽  
C. Della Coletta
Keyword(s):  
Cultural Heritage ◽  
3D Model ◽  
3D Models ◽  
World's Fair ◽  
Existing Structures ◽  
Present Generation ◽  
Technical Issues ◽  
Digital Documentation ◽  
3D Documentation ◽  
Model Visualization

Abstract. Rebuilding the past of cultural heritage through digitization, archiving and visualization by means of digital technology is becoming an emerging issue to ensure the transmission of physical and digital documentation to future generations as evidence of culture, but also to enable present generation to enlarge, facilitate and cross relate data and information in new ways. In this global effort, the digital 3D documentation of no longer existing cultural heritage can be essential for the understanding of past events and nowadays, various digital techniques and tools are developing for multiple purposes.In the present research the entire workflow, starting from archive documentation collection and digitization to the 3D models metrically controlled creation and online sharing, is considered. The technical issues to obtain a detail 3D model are examined stressing limits and potentiality of 3D reconstruction of disappeared heritage and its visualization exploiting three complexes belonging to 1911 Turin World’s Fair.

scholarly journals VERIFICATION OF POTENCY OF AERIAL DIGITAL OBLIQUE CAMERAS FOR AERIAL PHOTOGRAMMETRY IN JAPAN

2016 ◽  
Vol XLI-B1 ◽  
pp. 63-68 ◽  
Author(s):  
Ryuji Nakada ◽  
Masanori Takigawa ◽  
Tomowo Ohga ◽  
Noritsuna Fujii
Keyword(s):  
3D Model ◽  
3D Models ◽  
Aerial Photographs ◽  
Digital Cameras ◽  
Digital Mapping ◽  
Aerial Photogrammetry ◽  
Public Survey ◽  
Survey Accuracy ◽  
Left And Right ◽  
Simultaneous Adjustment

Digital oblique aerial camera (hereinafter called “oblique cameras”) is an assembly of medium format digital cameras capable of shooting digital aerial photographs in five directions i.e. nadir view and oblique views (forward and backward, left and right views) simultaneously and it is used for shooting digital aerial photographs efficiently for generating 3D models in a wide area. &lt;br&gt;&lt;br&gt; For aerial photogrammetry of public survey in Japan, it is required to use large format cameras, like DMC and UltraCam series, to ensure aerial photogrammetric accuracy. &lt;br&gt;&lt;br&gt; Although oblique cameras are intended to generate 3D models, digital aerial photographs in 5 directions taken with them should not be limited to 3D model production but they may also be allowed for digital mapping and photomaps of required public survey accuracy in Japan. &lt;br&gt;&lt;br&gt; In order to verify the potency of using oblique cameras for aerial photogrammetry (simultaneous adjustment, digital mapping and photomaps), (1) a viewer was developed to interpret digital aerial photographs taken with oblique cameras, (2) digital aerial photographs were shot with an oblique camera owned by us, a Penta DigiCAM of IGI mbH, and (3) accuracy of 3D measurements was verified.

The Influence of Carboxy Methyl Cellulose (CMC) and Solution pH on Carbon Fiber Dispersion in White Cement Matrix

2014 ◽  
Vol 493 ◽  
pp. 661-665 ◽  
Author(s):  
Ari Yustisia Akbar ◽  
Yulinda Lestari ◽  
Gilang Ramadhan ◽  
Septian Adi Candra ◽  
Eni Sugiarti
Keyword(s):  
Aqueous Solution ◽  
Carbon Fiber ◽  
Methyl Cellulose ◽  
Cement Matrix ◽  
Solution Ph ◽  
Fiber Dispersion ◽  
Reinforced Composite ◽  
Disperse Carbon ◽  
Reinforced Cement ◽  
Matrix Morphology

Dispersion of carbon fiber in cement matrix is one of main challenges for fabricating carbon fiber reinforced cement based materials. In this study, the dispersion of carbon fiber was improved by pre-dispersion of carbon fiber in basic aqueous solution using different concentrations of CMC. The relationships of CMC concentration and pH solution toward carbon fiber dispersion in aqueous solution was evaluated by UVvis spectroscopy. In order to understand how carbon fiber is dispersed in cement matrix, morphology fiber carbon reinforced composite was examined. Experimental results show that aqueous solution of CMC is effective to disperse carbon fiber. In addition, dispersion of carbon fiber increases with increasing of pH of CMC solution.

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