scholarly journals Corrosion Behavior of Pre-Rusted Rebars in Cement Mortar Exposed to Harsh Environments

2020 ◽  
Vol 10 (23) ◽  
pp. 8705
Author(s):  
Gankhuyag Burtuujin ◽  
Dasom Son ◽  
Indong Jang ◽  
Chongku Yi ◽  
Hyerin Lee
Keyword(s):  
Corrosion Rate ◽  
Cement Mortar ◽  
Cement Composite ◽  
Harsh Environments ◽  
Experimental Program ◽  
Cement Composites ◽  
X Ray Diffraction ◽  
Half Cell ◽  
Cell Potential ◽  
X Ray

Rebar embedded inside reinforced concrete structures becomes corroded due to various factors. However, few studies have focused on the corrosion of pre-rusted rebar embedded in cement composites, and the findings reported thus far are inconsistent. Therefore, in this study, an experimental program was undertaken to examine the effect of pre-rusting on the further corrosion of reinforcements in cement composites. Pre-rust was induced using two different solutions (CaCl2 and HCl). The corrosion rate in the cement composite was analyzed using the half-cell potential and polarization resistance methods. In addition, scanning electron microscopy with energy-dispersive X-ray analysis and X-ray diffraction analysis were used to examine the morphology of the rust. The results show that the corrosion rate of the rebar embedded in the cement composite can be increased by more than 3.8 times depending on the pre-rust conditions (RE: 0.0009 mm/year, HCl: 0.0035 mm/year). In addition, we found that the corrosion products in the pre-rusted layer were comparable to those of the rebar corroded in the marine atmosphere.

scholarly journals Test of inhibitors for preventing corrosion of steel reinforcement in concrete

2021 ◽  
Vol 32 (2) ◽  
pp. 110-113
Author(s):  
Albana Jano ◽  
Alketa Lame ◽  
Efrosini Kokalari
Keyword(s):  
Corrosion Rate ◽  
Polarization Resistance ◽  
Guar Gum ◽  
Cement Mortar ◽  
Extrapolation Methods ◽  
Half Cell ◽  
Cell Potential ◽  
Reinforced Cement ◽  
Locust Bean ◽  
Corrosion Of Steel

Abstract Concrete is more widely used than any other manmade material. The objective of this paper is to investigate the behavior of reinforced cement when migration corrosion and guar gum inhibitors are used. The concrete samples were exposed in aggressive media H2SO4 1 M and in the presence of 1∙10-3 M Cl-. Electrochemical measurements such as half-cell potential, polarization resistance and Tafel extrapolation methods were performed in order to obtain information on the corrosion behavior of the reinforcing steel in cement mortar. Results demonstrate high resistance polarization and low corrosion rate for concrete sample with inhibitor. The corrosion rate decreases approximately 95% in presence of locust bean gum and 80% in presence of migration inhibitor.

scholarly journals Field investigation of slab deterioration due to carbonation in a concrete building

2019 ◽  
Vol 289 ◽  
pp. 10001 ◽  
Author(s):  
Eleni B. Araya ◽  
Stephen Ekolu ◽  
Fitsum Solomon
Keyword(s):  
Residential Building ◽  
Field Investigation ◽  
X Ray Diffraction ◽  
Half Cell ◽  
Cell Potential ◽  
X Ray ◽  
Concrete Building ◽  
Test Cover ◽  
Story Building ◽  
Non Destructive

This paper presents an investigation on a deteriorated slab of a two-story building located in Johannesburg, South Africa. The structure has been in use as a residential building for more than 60 years. The top slab of the first floor was delaminated and reinforcement bars were severely corroded. Condition assessment of the building was done using the Schmidt hammer test, cover-meter survey and half-cell potential measurements. In addition to the non-destructive tests done, X-ray diffraction and scanning electron microscopy were also conducted on the deteriorated concrete.

Nano Colorful Cement Composite

2013 ◽  
Vol 313-314 ◽  
pp. 103-107
Author(s):  
A. Kazemi Babaheydari ◽  
M. Asad-Zadeh ◽  
F. Mohammadi
Keyword(s):  
Mechanical Properties ◽  
Cement Mortar ◽  
Average Diameter ◽  
Cement Composite ◽  
Partial Replacement ◽  
Gel Formation ◽  
Replacement Level ◽  
X Ray Diffraction ◽  
X Ray ◽  
Sem Study

The purpose of this study is to investigate the strength and mechanical properties of concrete by partial replacement of cement with nano-pigment particles. Nano-pigment particles with the average diameter of 120 nm were used with ten different contents of 0.5%, 0.1%, 1.5% and 4.0% by weight. have been investigated by scan electron microscopy(SEM) ,¬X-ray diffraction(XRD).The results showed that the use of nano- pigment particles up to maximum replacement level of 4.0% produces concrete with improved strength and mechanical properties The SEM study of the microstructures between the cement mortar mixed with the nano-pigment particles and the plain cement mortar showed that the nano-pigment particles as a partial replacement of cement up to 4 wt% could accelerate C–S–H gel formation as a result of the increased crystalline Ca(OH)2 amount at the early ages of hydration.

The Influence of Limestone Powder on Fluidity, Strength and Hydration of Cement Mortar

2010 ◽  
Vol 168-170 ◽  
pp. 512-517 ◽  
Author(s):  
Hua Shan Yang ◽  
Kun He Fang ◽  
Sheng Jin Tu
Keyword(s):  
Cement Mortar ◽  
Xrd Analysis ◽  
Water Requirement ◽  
Limestone Powder ◽  
Experimental Program ◽  
Test Results ◽  
Hydration Products ◽  
X Ray Diffraction ◽  
X Ray ◽  
The Relationship

An experimental program has been conducted to investigate the influence of limestone powder (LP) on fluidity, strength, and hydration of cement mortar. Four laboratory grinds were prepared using a ball mill. The relationship between roundness of the LP and water requirement of paste, fluidity and strength of mortar was studied. The influence of LP on hydration of cement was investigated. Hydration products were determined by X-ray diffraction (XRD) analysis. Test results show that the roundness of LP significantly affected the water requirement of paste, fluidity and strength of mortar. In addition, the sites for the nucleation and growth of hydration products, provided by LP, accelerate the hydration of cement at early ages. While the enhancement of cement hydration at later ages mainly due to the formation of calcium aluminate monocarbonate.

scholarly journals Industrial Waste Utilization of Carbon Dust in Sustainable Cementitious Composites Production

Materials ◽  
2020 ◽  
Vol 13 (15) ◽  
pp. 3295
Author(s):  
Mohammad R. Irshidat ◽  
Nasser Al-Nuaimi
Keyword(s):  
Compressive Strength ◽  
Industrial Waste ◽  
Cement Mortar ◽  
Waste Utilization ◽  
Cementitious Composites ◽  
X Ray Diffraction ◽  
Sem Images ◽  
Compact Structure ◽  
X Ray ◽  
Industrial Waste Utilization

This paper experimentally investigates the effect of utilization of carbon dust generated as an industrial waste from aluminum factories in cementitious composites production. Carbon dust is collected, characterized, and then used to partially replace cement particles in cement mortar production. The effect of adding different dosages of carbon dust in the range of 5% to 40% by weight of cement on compressive strength, microstructure, and chemical composition of cement mortar is investigated. Scanning electron microscopy (SEM), X-ray diffraction (XRD), and X-ray fluorescence (XRF) analysis are used to justify the results. Experimental results show that incorporation of carbon dust in cement mortar production not only reduces its environmental side effects but also enhances the strength of cementitious composites. Up to 10% carbon dust by weight of cement can be added to the mixture without adversely affecting the strength of the mortar. Any further addition of carbon dust would decrease the strength. Best enhancement in compressive strength (27%) is achieved in the case of using 5% replacement ratio. SEM images show that incorporation of small amount of carbon dust (less than 10%) lead to produce denser and more compact-structure cement mortar.

Fabrication and in Vitro Evaluation of Calcium Phosphate Combined with Chitosan Fibers for Scaffold Structures

2009 ◽  
Vol 24 (1_suppl) ◽  
pp. 113-124 ◽  
Author(s):  
Qin Lian ◽  
Dichen Li ◽  
Zhongmin Jin ◽  
Jue Wang ◽  
Aimin Li ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Calcium Phosphate ◽  
In Vitro Study ◽  
Cement Composites ◽  
X Ray Diffraction ◽  
X Ray ◽  
Chitosan Fiber ◽  
In Vitro Performance ◽  
Rapid Tool

A rapid prototyping and rapid tool technique-based method was developed to fabricate chitosan fiber calcium phosphate cement composites (CF/CPC) for bone tissue engineering scaffold applications. The products were characterized and the in vitro performance with canine bone marrow stem cells (BMCs) on CF/CPC scaffold with controlled fiber structures evaluated. The X-ray diffraction analysis showed that about 91% of the inorganic part of the CF/CPC scaffold was hydroxyapatite (HA) and the variation in CF had little effect on the percentage of HA content. The results from in vitro study demonstrated that the interconnected macropores rapidly formed inside the CF/CPC scaffolds and that the patterns were related to the fiber structures used. The differences in the fiber structures altered the morphology of the BMCs without affecting the proliferation of the BMCs.

UHPC and FRC in Severe Environmental Conditions

2016 ◽  
Vol 711 ◽  
pp. 412-419 ◽  
Author(s):  
Stanislav Rehacek ◽  
Ivo Simunek ◽  
David Citek ◽  
Jiří Kolísko
Keyword(s):  
Environmental Conditions ◽  
Cement Composite ◽  
Joint Effect ◽  
Experimental Program ◽  
Cement Composites ◽  
Structure And Properties ◽  
Physical Chemical ◽  
Chemical Agents ◽  
Macro Scale ◽  
Scale Properties

Structure and properties of cement composite are time-varying characteristics, depending among others on environmental conditions. The key idea is a struggle for complex research of joint effect of physical, chemical and dynamic loads on the internal structure [1] of cement composite and understanding the correlation between changes in microstructure and macro-scale properties [2, 3]. During the experimental program, specimens will be exposed to combined influence of freeze-thaw cycles [4,5,6], aggressive chemical agents [7] and dynamic loading [8]. The aim is to create a theoretical basis for design of effective cement composites meant to be used in severe environmental conditions.

Selective Electrolytic Corrosion Behaviours of WC in WC-Co Cemented Carbide

2017 ◽  
Vol 898 ◽  
pp. 1478-1484 ◽  
Author(s):  
Zhong Wu Li ◽  
Cheng Guang Lin ◽  
Xing Cheng Xie ◽  
Rui Jun Cao ◽  
Zhong Kun Lin
Keyword(s):  
Grain Size ◽  
Corrosion Rate ◽  
Cemented Carbide ◽  
Cemented Carbides ◽  
X Ray Diffraction ◽  
X Ray ◽  
Electrolytic Corrosion ◽  
Mean Grain Size ◽  
Diffraction Peaks ◽  
Corrosion Time

In this work, WC grains in WC-Co cemented carbide were selectively electrolytic corroded and the effects of corrosion time, WC mean grain size and Co content on corrosion rate were systematically investigated. The results showed that corrosion rate decreased with the prolonging of electrolytic corrosion time. The WC-9Co cemented carbides had grain size of 2.9 μm The intensity of Co diffraction peaks was found to exceed the WC diffraction peaks when corroded for 4 hours, and the WC diffraction peaks disappeared when corroded for 8 hours. The corrosion rate increased with the decrease of WC mean grain size and the Co content. As the WC content increased in cemented carbide, it was necessary to increase corrosion time when analyzed Co phase in the cemented carbide by X-ray diffraction.

Magnesium Phosphate Cement with Large Volume of Fly Ash

2012 ◽  
Vol 174-177 ◽  
pp. 802-805 ◽  
Author(s):  
Zhu Ding ◽  
Bi Qin Dong ◽  
Feng Xing
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Large Volume ◽  
Sodium Phosphate ◽  
Cement Mortar ◽  
Cementitious Materials ◽  
X Ray Diffraction ◽  
Monoammonium Phosphate ◽  
Ammonia Gas ◽  
X Ray

The accumulation of fly ash leads to severe problems in ecological environments. Various ways to excite the activity of fly ash in Portland cement based cementitious materials have been carried out for many years. In the present study, effect of large volume of fly ash in phosphate cement was studied. Dead burned magnesia, two phosphates (monoammonium phosphate and monosodium phosphate), and fly ash were used. The fabricated cement mortar specimens with different fly ash dosages were cured for 28 days in the lab air. Compressive strength was determined in 1d, 3d, 7d and 28d respectively. It is showed the compressive strength reduced with increase of fly ash content and increased with the curing time. After cured 28 days, the compressive strength of cement mortar developed to14MPa, when 80% fly ash was used. The reaction product, Na2HPO4•17H2O was found by X-ray diffraction analysis in sodium phosphate based cement. No ammonia gas was emitted and large volume of fly ash can be used in cement prepared from sodium phosphate. It is a new environmentally friendly cement material.

Research on Solid Wastes of Gangue, Slag, Fly Ash Used as Cement Composite Mixing Materials

2011 ◽  
Vol 415-417 ◽  
pp. 1486-1489
Author(s):  
Jian Guo Liao ◽  
Qian Ma ◽  
Yi Shun Zhang ◽  
Zhi Yang Song ◽  
Kai Hang Liu ◽  
...  
Keyword(s):  
Fly Ash ◽  
Cement Composite ◽  
Sem Analysis ◽  
Solid Wastes ◽  
X Ray Diffraction ◽  
Compact Structure ◽  
X Ray ◽  
Before And After ◽  
Mixed Material ◽  
Cement Strength

The purpose of this study is to bring the fly ash, coal gangue and slag industrial solid wastes which contain the chemical composition for activation treatment, used as activated composite cement mixing materials, through strength test shows that the compound mixing materials impermeability activation treatment can obviously increase the cement strength. X-ray diffraction analysis (XRD), scanning electron microscopy (SEM) analysis results showed that the crystal structure of the mixed material calcined before and after have apparent change. There are lesss hydration products with compact structure of cement hydration 3d. The early strength of aiding composite mixing materials cement improved greatly.

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