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Full-Text Articles in Engineering

A Laboratory Investigation Of Cement Based Materials With Cellulose Nanofibers, Parivash Takasi Dec 2019

A Laboratory Investigation Of Cement Based Materials With Cellulose Nanofibers, Parivash Takasi

Electronic Theses and Dissertations

Cellulose Nanofibers (CNFs) are used as additives in cement-based products to modify their properties. Recent studies about the effects of CNFs on cement paste showed inconsistent results for several different important properties, including compressive strength and free shrinkage. There is reason to believe that the unsystematic results of the compressive strengths were affected by the lack of uniform dispersion of CNFs. As a potential remedy, two different mixing methods were applied. The first method used a basic mixer, but aggregates were added to the cement paste mixture to improve the blending process. The second method utilized a high-speed shear mixer ...


Performance Of High-Volume Fly Ash Self-Compacting Concrete Exposed To External Sulfate Attack, Tareq S. Al-Attar Dr., A. A. Taha Nov 2019

Performance Of High-Volume Fly Ash Self-Compacting Concrete Exposed To External Sulfate Attack, Tareq S. Al-Attar Dr., A. A. Taha

International Conference on Durability of Concrete Structures

The high-volume fly ash concrete, HVFAC, could be defined as any concrete mix having fly ash content larger than 50 percent of the total cementitious materials content. Due to the availability of fly ash in large quantities globally with low cost, HVFAC could be considered as a solution for the environmental impact of Portland cements. In this study the durability of two high-volume fly ash self-compacting concrete, HVFASCC, mixes exposed to the effects of two sulfate aggressive solutions was investigated. The fly ash, class F, contents for these mixes were 50 and 60 percent by weight of Portland cement. The ...


Effect Of Mix Parameters On Strength Of Geopolymer Mortars - Experimental Study, Abdolhossein Naghizadeh, Stephen O. Ekolu Nov 2019

Effect Of Mix Parameters On Strength Of Geopolymer Mortars - Experimental Study, Abdolhossein Naghizadeh, Stephen O. Ekolu

International Conference on Durability of Concrete Structures

In this article, an investigation is reported on development of strength in South African fly ash (FA) – based geopolymer mixtures. Locally available Class F, FA from one of the coal power stations was used in the investigation. The alkali-activator used consisted of sodium silicate (SS) and sodium hydroxide (SH) mixed in varied ratios of 1.0, 1.5, 2.0, 2.5 and 3.0 SS to SH. The SS of silicate modulus = 2.5 was used but the SH concentration in the activator was varied to 10, 12, 14M NaOH. Mortars of 2.25 aggregate/binder ratio were used ...


Compressive Strength, Free Expansion And Shrinkage Of Expansive Concrete Containing Fly Ash, Warangkana Saengsoy, Rachot Chatchawan, Somnuk Tangtermsirikul Nov 2019

Compressive Strength, Free Expansion And Shrinkage Of Expansive Concrete Containing Fly Ash, Warangkana Saengsoy, Rachot Chatchawan, Somnuk Tangtermsirikul

International Conference on Durability of Concrete Structures

This study is aimed to investigate effect of fly ash on compressive strength, free expansion and shrinkage of expansive concrete. High CaO and low CaO fly ashes are used in this study. The replacement percentages of total binders by fly ash are 0 and 30% by weight. The replacements of expansive additive are 0, 20 and 30 kg/m3 of concrete. The test results revealed that the use of fly ash especially the high CaO fly ash can enhance expansion of expansive concrete at early age. The use of fly ash also reduces shrinkage at long term of the ...


Mechanical Properties Of Hydrogenated Amorphous Silicon (A-Si:H) Particles, Taizhi Jiang, Fardin Khabaz, Aniket Marne, Chenglin Wu, Raluca Gearba, Revanth Bodepudi, Roger T. Bonnecaze, Kenneth M. Liechti, Brian A. Korgel Nov 2019

Mechanical Properties Of Hydrogenated Amorphous Silicon (A-Si:H) Particles, Taizhi Jiang, Fardin Khabaz, Aniket Marne, Chenglin Wu, Raluca Gearba, Revanth Bodepudi, Roger T. Bonnecaze, Kenneth M. Liechti, Brian A. Korgel

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

A nanoindenter was used to compress individual particles of hydrogenated amorphous silicon (a-Si:H) ranging in diameter from 290 nm to 780 nm. The colloidal synthesis used to produce the particles enables the hydrogen content to be manipulated over a wide range, from about 5 at. % to 50 at. %, making these a-Si:H particles promising for applications in lithium ion batteries, hydrogen storage, and optical metamaterials. Force-displacement curves generated using a tungsten probe flattened with focused ion beam exhibited elastic and then plastic deformations, followed by fracture and crushing of the particles. For particles with 5% and 50% H, Young ...


A Relationship Between The Strengths Of Type N Cubic Mortar Specimens And In-Situ Mortar, Michael Scott Reynolds May 2019

A Relationship Between The Strengths Of Type N Cubic Mortar Specimens And In-Situ Mortar, Michael Scott Reynolds

Theses and Dissertations

The compressive strength of mortar is typically determined using the American Societyfor Testing and Materials (ASTM) standard method using 2 inch cubes which are compressed tillfailure. There is however a disparity between the compressive strengths of mortar cubes, and insitumortar. This disparity is a result of the differences in thickness, aspect ratio, curingconditions, water content, and confinement between mortar cubes and mortar joints. While thesedifferences lead to mortar joints being stronger than mortar cubes, a relationship between theirstrengths is desired.Two less-common mortar strength tests were used to determine more accurately thecompressive strength of in-situ mortar. The results of both ...


The Effect Of Fine And Coarse Recycled Aggregates On Fresh And Mechanical Properties Of Self-Compacting Concrete, Mahmoud Nili, Hossein Sasanipour, Farhad Aslani Apr 2019

The Effect Of Fine And Coarse Recycled Aggregates On Fresh And Mechanical Properties Of Self-Compacting Concrete, Mahmoud Nili, Hossein Sasanipour, Farhad Aslani

ECU Publications Post 2013

Today, the use of recycled aggregates as a substitute for a part of the natural aggregates in concrete production is increasing. This approach is essential because the resources for natural aggregates are decreasing in the world. In the present study, the effects of recycled concrete aggregates as a partial replacement for fine (by 50%) and coarse aggregates (by 100%) were examined in the self-compacting concrete mixtures which contain air-entraining agents and silica fumes. Two series of self-compacting concrete mixes have been prepared. In the first series, fine and coarse recycled mixtures respectively with 50% and 100% replacement with air entraining ...


Development Of Heavyweight Self-Compacting Concrete And Ambient-Cured Heavyweight Geopolymer Concrete Using Magnetite Aggregates, Afsaneh Valizadeh, Farhad Aslani, Zohaib Asif, Matt Roso Mar 2019

Development Of Heavyweight Self-Compacting Concrete And Ambient-Cured Heavyweight Geopolymer Concrete Using Magnetite Aggregates, Afsaneh Valizadeh, Farhad Aslani, Zohaib Asif, Matt Roso

ECU Publications Post 2013

Heavyweight self-compacting concrete (HWSCC) and heavyweight geopolymer concrete (HWGC) are new types of concrete that integrate the advantages of heavyweight concrete (HWC) with self-compacting concrete (SCC) and geopolymer concrete (GC), respectively. The replacement of natural coarse aggregates with magnetite aggregates in control SCC and control GC at volume ratios of 50%, 75%, and 100% was considered in this study to obtain heavyweight concrete classifications, according to British standards, which provide proper protection from sources that emit harmful radiations in medical and nuclear industries and may also be used in many offshore structures. The main aim of this study is to ...


Air Void Clustering In Retempering Concrete And Its Contribution To Compressive Strength, Wen Sun Jan 2019

Air Void Clustering In Retempering Concrete And Its Contribution To Compressive Strength, Wen Sun

Graduate Theses and Dissertations

Air void clustering is a phenomenon in concrete in which air bubbles accumulate around the coarse aggregate. It is considered as a major cause of reduction of concrete strength.

This thesis focuses on the effect of different variables on air void clustering and its contribution to the performance of concrete. Six variables were considered in the study, including cement type (low alkali cement and TIL cement), fly ash (fly ash A and B), coarse aggregate type (lime stone and river gravel), chemical admixture type (admixture 1 and 2) , mixing water temperature (70℉ and 90℉), and retempering (with and without). A ...


Investigating The Use Of In-Place Lateral Pull Off Tests To Determine The Compressive Strength Of Structural Concrete, Charlie Sun Jan 2019

Investigating The Use Of In-Place Lateral Pull Off Tests To Determine The Compressive Strength Of Structural Concrete, Charlie Sun

Kentucky Transportation Center Research Report

The Kentucky Transportation Cabinet’s current practice for determining the compressive strength of structural concrete consists of two methods. Both methods require that samples be delivered to an off-site facility for testing. Accordingly, affected parties on the project site must wait for the delivery of samples to the off-site facility, the performance of tests and analysis of test data, and the return of test results to the project site. Analysis of existing structural concrete requires core samples to be taken from the structural element in question. As a result, sample locations must be patched and repaired. Sampling can also potentially ...


Properties Of Ambient-Cured Normal And Heavyweight Geopolymer Concrete Exposed To High Temperatures, Farhad Aslani, Zohaib Asif Jan 2019

Properties Of Ambient-Cured Normal And Heavyweight Geopolymer Concrete Exposed To High Temperatures, Farhad Aslani, Zohaib Asif

ECU Publications Post 2013

Ambient-cured heavyweight geopolymer concrete (HWGC) is a new type of concrete that combines the benefits of both heavyweight concrete (HWC) and geopolymer concrete (GC). HWGC provides proper protection from the sources that emit harmful radiations in medical and nuclear industries. Furthermore, HWGC may also be used in offshore structures for pipeline ballasting and similar underwater structures. In this study, heavyweight aggregates (magnetite) have been used and replaced by normal-weight coarse aggregates in GC at volume ratios of 50, 75, and 100% to attain heavyweight classification according to British standards. This study investigates the impacts of high temperatures on standard ambient-cured ...


Fire Performance Of Heavyweight Self-Compacting Concrete And Heavyweight High Strength Concrete, Farhad Aslani, Fatemeh Hamidi, Qilong Ma Jan 2019

Fire Performance Of Heavyweight Self-Compacting Concrete And Heavyweight High Strength Concrete, Farhad Aslani, Fatemeh Hamidi, Qilong Ma

ECU Publications Post 2013

In this study, the fresh and hardened state properties of heavyweight self-compacting concrete (HWSCC) and heavyweight high strength concrete (HWHSC) containing heavyweight magnetite aggregate with 50, 75, and 100% replacement ratio, and their performance at elevated temperatures were explored experimentally. For fresh-state properties, the flowability and passing ability of HWSCCs were assessed by using slump flow, T500 mm, and J-ring tests. Hardened-state properties including hardened density, compressive strength, and modulus of elasticity were evaluated after 28 days of mixing. High-temperature tests were also performed to study the mass loss, spalling of HWSCC and HWHSC, and residual mechanical properties at 100 ...


Beta-Type Ti-Nb-Zr-Cr Alloys With Large Plasticity And Significant Strain Hardening, Syed F. Jawed, Chirag D. Rabadia, Y. J. Liu, L. Q. Wang, Y. H. Li, X. H. Zang, Laichang C. Zhang Jan 2019

Beta-Type Ti-Nb-Zr-Cr Alloys With Large Plasticity And Significant Strain Hardening, Syed F. Jawed, Chirag D. Rabadia, Y. J. Liu, L. Q. Wang, Y. H. Li, X. H. Zang, Laichang C. Zhang

ECU Publications Post 2013

A series of Ti-25Nb-8Zr-xCr (x = 0, 2, 4, 6, 8 wt%) alloys were designed based on DV-Xα cluster method and e=a-Δr diagram with an anticipation to obtain high plasticity and significant strain hardening. The designed alloys were produced through cold crucible levitation melting technique in order to effectively investigate their micro-structures and mechanical properties. The addition of Cr significantly enhances the β stability in the microstructures of the Ti-25Nb-8Zr-xCr alloys. Both yield strength and hardness of the studied alloys increase due to the effect of solid-solution strengthening. By contrast, the plasticity, maximum strength and strain hardening rate are influenced ...