scholarly journals Combined Freeze-Thaw and Chloride Attack Resistance of Concrete Made with Recycled Brick-Concrete Aggregate

Materials ◽  
2021 ◽  
Vol 14 (23) ◽  
pp. 7267
Author(s):  
Yao Yu ◽  
Jian Wang ◽  
Ninghui Wang ◽  
Chenjie Wu ◽  
Xiaojing Zhang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Fly Ash ◽  
Sodium Chloride ◽  
Chemical Properties ◽  
Chloride Content ◽  
Chloride Ions ◽  
Water Soluble ◽  
Concrete Aggregate ◽  
Freeze Thaw ◽  
Chloride Attack

The objective of this study was to investigate the physico-chemical properties of concrete made with recycled brick-concrete aggregate, which was the mixture from waste concrete and waste clay brick in a 7:3 ratio. Specifically, this paper investigated the mechanical properties, freeze-thaw resistance, and distribution of water-soluble chloride ions of concrete containing RBCA and fly ash (FA) against combined freeze-thaw and sodium chloride attack. Concrete containing RBCA replacement of natural coarse aggregate and fly ash replacement of Portland cement was subjected to 45 freeze-thaw cycles containing sodium chloride solution. It was discovered that the mechanical properties and freeze-thaw resistance to sodium chloride attack gradually decreased with increasing RBCA content. At the same time, a replacement level of 15% FA by weight resulted in significant improvements in compressive strength and resistance to combined freeze-thaw and chloride attack. Furthermore, using a replacement of 30% FA by weight markedly improved the resistance to chloride ion penetration of concrete due to the lowest water-soluble chloride content.

Mechanical Properties of Mortars Prepared by Alkali Activated Fly Ash Coming from Different Production Batches

2015 ◽  
Vol 244 ◽  
pp. 140-145 ◽  
Author(s):  
Matej Špak ◽  
Pavel Raschman
Keyword(s):  
Mechanical Properties ◽  
Fly Ash ◽  
Construction Materials ◽  
Chemical Properties ◽  
Raw Material ◽  
Fly Ashes ◽  
Coal Burning ◽  
Alkali Solutions ◽  
One Year ◽  
Alkali Activated

Fly ash is a well utilizable secondary raw material for the production of alkali activated construction materials. It is a significant alumina-silicates source suitable for the chemical reaction resulting in hardened composites. Physical and chemical properties of fly ashes as a co-product of coal burning mainly depend on characteristics of coal, burning temperature and combustion conditions. High variability of the properties of fly ash causes an uncertainty in the properties of alkali activated mortars. Time behaviour of the composition of the fly ash produced in a heating plant located in Košice, Slovakia as well as leaching behaviour of both alumina and silica from particular batches during one-year period was documented. Leaching tests were carried out using the distilled water and alkali solutions with three different concentrations. Both compressive and tensile strengths of alkali activated mortars were measured, and the correlation between the mechanical properties of hardened mortars and the chemical composition of fly ashes as well as their leaching characteristics was investigated.

scholarly journals Effect of Fly Ash as Cement Replacement on Chloride Diffusion, Chloride Binding Capacity, and Micro-Properties of Concrete in a Water Soaking Environment

2020 ◽  
Vol 10 (18) ◽  
pp. 6271 ◽  
Author(s):  
Jun Liu ◽  
Jiaying Liu ◽  
Zhenyu Huang ◽  
Jihua Zhu ◽  
Wei Liu ◽  
...  
Keyword(s):  
Diffusion Coefficient ◽  
Fly Ash ◽  
Binding Capacity ◽  
Chloride Ion ◽  
Chloride Content ◽  
Chloride Ions ◽  
Chloride Diffusion ◽  
Chloride Binding ◽  
Test Results ◽  
New Equation

This paper experimentally studies the effects of fly ash on the diffusion, bonding, and micro-properties of chloride penetration in concrete in a water soaking environment based on the natural diffusion law. Different fly ash replacement ratio of cement in normal concrete was investigated. The effect of fly ash on chloride transportation, diffusion, coefficient, free chloride content, and binding chloride content were quantified, and the concrete porosity and microstructure were also reported through mercury intrusion perimetry and scanning electron microscopy, respectively. It was concluded from the test results that fly ash particles and hydration products (filling and pozzolanic effects) led to the densification of microstructures in concrete. The addition of fly ash greatly reduced the deposition of chloride ions. The chloride ion diffusion coefficient considerably decreased with increasing fly ash replacement, and fly ash benefits the binding of chloride in concrete. Additionally, a new equation is proposed to predict chloride binding capacity based on the test results.

Influence of Fluidized Fly Ash on the Selected Physical-Mechanical Properties of the Autoclaved Aerated Concrete

2014 ◽  
Vol 899 ◽  
pp. 409-414 ◽  
Author(s):  
Alena Struhárová ◽  
Stanislav Unčík ◽  
Svetozár Balkovic ◽  
Mária Hlavinková
Keyword(s):  
Mechanical Properties ◽  
Fly Ash ◽  
Chemical Properties ◽  
Physical And Chemical Properties ◽  
Amorphous Phases ◽  
Autoclaved Aerated Concrete ◽  
Aerated Concrete ◽  
Free Cao ◽  
Physical And Chemical ◽  
And Chemical Properties

Fluidized fly ash has different physical and chemical properties compared to fly ash emerging from classic combustion. It contains amorphous phases resulting from a dehydration of clay minerals as well as unreacted sorbent of CaCO3, free CaO and anhydrite (CaSO4). Work targets the possibilities of production of an autoclaved aerated concrete (AAC) from fluidized fly ash, and its influence on particular physical-mechanical properties of autoclaved aerated concrete.

scholarly journals Durability Behavior of Self Compacting Concrete Made with Recycled Concrete Aggregate

2018 ◽  
Vol 7 (3.35) ◽  
pp. 16
Author(s):  
T. V. Arul Prakash ◽  
Dr. M. Natarajan ◽  
Dr. T. Senthil Vadivel ◽  
Dr. V.Karthik ◽  
. .
Keyword(s):  
Fly Ash ◽  
Recycled Concrete ◽  
Concrete Aggregate ◽  
Recycled Concrete Aggregate ◽  
Self Compacting Concrete ◽  
Chloride Attack ◽  
Local Construction ◽  
Water Absorption Test ◽  
Class F Fly Ash ◽  
Strength And Durability

This article presents the influence of the Recycled Concrete Aggregate (RCA) on the durability behavior of self-compacting fly ash concrete (M30 Grade). The RCA from local construction demolition site wereemployed as a replacement for natural coarse aggregate (0% - 30%) in self-compacting concrete(SCC). The Viscosity modifying material used in this study was Class F fly ash. Different kinds of tests were conducted on the concrete specimens such as water absorption test, sulphate attack, chloride attack, carbonation test,sorptivity test, etc., When the durability behavior was taken into consideration,the summary of results indicate that recycled concrete aggregate different percentage of replacements as the optimal percentagein the manufacture of SCC without much affecting strength and durability. 

Potentiometric Titration Methods for the Determination of Sodium Chloride in Certifiable Water-Soluble Colors: Collaborative Study

1980 ◽  
Vol 63 (3) ◽  
pp. 572-580
Author(s):  
Wallace S Brammell ◽  
◽  
F R Clark ◽  
R H Downey ◽  
A Goldberg ◽  
...  
Keyword(s):  
Sodium Chloride ◽  
Potentiometric Titration ◽  
Collaborative Study ◽  
Chloride Content ◽  
Water Soluble ◽  
Titration Method ◽  
Manual Method ◽  
Low Sodium ◽  
Automated Method ◽  
Potentiometric Titration Method

Abstract In a collaborative study, 7 laboratories successfully analyzed 8 different samples, in duplicate, by a manual potentiometric titration method. These same samples were used by 7 different laboratories in a concurrent collaborative study of the automated potentiometric titration method. The samples are dissolved in water and acidified, and soluble chloride is determined by titration with silver nitrate to the potentiometric end point. The methods are applicable to all water-soluble certifiable colors except D&C Red No. 19, at levels >0.03% sodium chloride, although there is a positive error at very low levels for the automated titration. In halogenated fluoresceins, any iodide or bromide is determined as sodium chloride, but the maximum amount normally present is equivalent to <0.2% sodium chloride. The sodium chloride content of the collaborative samples ranged from 0.04 to 18.2% for the manual method, and from 0.11 to 18.1% for the automated method. In general, except at very low sodium chloride levels, the precision of the automated method was good, although not as high as that for the manual method; single determination coefficients of variation ranged from 1.5 to 13.5% for the former, and from 1.2 to 2.7% for the latter. Recovery of 0.45% added sodium chloride ranged from 62 to 96%, and for 4.5% added sodium chloride it varied from 94 to 99% by the automated method. Recoveries ranged from 96 to 104% for 0,45% added sodium chloride and from 98 to 102% for 4.5% added sodium chloride by the manual method. The coefficient of correlation of the sample means for the manual and the automated methods was 0.9999%. The methods have been adopted as official first action.

Enhancement of mechanical properties of fly ash geopolymer containing fine recycled concrete aggregate with micro carbon fiber

2021 ◽  
pp. 102403
Author(s):  
Peem Nuaklong ◽  
Ampol Wongsa ◽  
Kornkanok Boonserm ◽  
Chanchai Ngohpok ◽  
Pitcha Jongvivatsakul ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Fly Ash ◽  
Carbon Fiber ◽  
Recycled Concrete ◽  
Concrete Aggregate ◽  
Recycled Concrete Aggregate

scholarly journals Under-insulation corrosion as a factor in decreased service life of industrial pipelines

2020 ◽  
Vol 10 (2) ◽  
pp. 264-273
Author(s):  
Victor N. Sokov ◽  
◽  
Elena A. Shuvalova ◽  
Anatoliy S. Zemlyanko ◽  
◽  
...  
Keyword(s):  
Carbon Steel ◽  
Service Life ◽  
Corrosion Rate ◽  
Thermal Insulation ◽  
Pitting Corrosion ◽  
Chloride Content ◽  
Chloride Ions ◽  
Water Soluble ◽  
Insulation Material ◽  
Critical Depth

The effect of porosity type and residual number of water-soluble chloride ions of insulation material on the under-insulation corrosion rate in industrial pipelines is considered. For the research, standard test methods were used in accordance with current Russian and foreign regulatory and technical documentation. The dependences of the corrosion rate and the damage area of carbon steel on the structure (porosity) of the thermal insulation material (open, semi-closed, closed), the residual number of water-soluble chloride ions and water-repellent agent is established. The residual life of a carbon steel pipeline was calculated at a critical depth of pitting corrosion under a thermal insulation layer of various materials. The types of thermal insulation materials characterised with lowest under-insulation corrosion rate are determined. The maximum 0.29–0.41 mm/year corrosion rate of carbon steel under materials with open porosity was 0.53–1.8 times lower than under comparable materials with closed porosity. An increased corrosion rate is determined to be directly proportional to an increase in the number of chlorine anions in the structure of the material. The smallest area of steel surface corrosion damage is observed under materials with open porosity. Among the materials examined, the requirements of the current regulatory standards are met by materials of the stone wool group having a low chloride content and basalt super thin fibre. The longest remaining service life (11 years) of a carbon steel pipeline at hdef= 5.87 mm critical depth of pitting corrosion is obtained under a rock wool layer having a low chloride content.

scholarly journals PHYSICAL AND MECHANICAL PROPERTIES RESEARCH AND ANALYSIS OF CONCRETE WITH BIOFUEL COMBUSTION FLY ASH SUPPLEMENT

2019 ◽  
Vol 11 (0) ◽  
pp. 1-5
Author(s):  
Deividas Augutis ◽  
Džigita Nagrockienė
Keyword(s):  
Mechanical Properties ◽  
Fly Ash ◽  
Physical And Mechanical Properties ◽  
Ultrasonic Pulse Velocity ◽  
Ultrasonic Pulse ◽  
Pulse Velocity ◽  
Ash Content ◽  
Closed Porosity ◽  
Freeze Thaw ◽  
Materials Used

Materials used for the study: Portland cement CEM I 42,5 R, 0/4 fraction sand, 4/16 fraction gravel, biofuel fly ash, superplastizer ViscoCrete D187 (V) and water. Seven compositions of concrete were designed by replacing 0%, 5%, 10%, 15%, 20%, 25% and 30% of cement with biofuel fly ash. The article analyses the effect of biofuel fly ash content on the properties of concrete. Studies have shown that the increase of biofuel fly ash content up to 15% increases concrete density and compressive strengh after 28 days of curing, compressive strength, ultrasonic pulse velocity, closed porosity, concrete forecasted freeze-thaw cycles and decreases water absorbtion, open porosity.

Corrosion Rate of Steel in Fly Ash Concrete Containing Chlorides

2015 ◽  
Vol 1110 ◽  
pp. 107-112 ◽  
Author(s):  
Keiji Miyata ◽  
Takao Ueda ◽  
Masayuki Tsukagoshi
Keyword(s):  
Fly Ash ◽  
Corrosion Rate ◽  
Environmental Temperature ◽  
Electrochemical Corrosion ◽  
Chloride Content ◽  
Fine Aggregate ◽  
Experimental Conditions ◽  
Suppression Effect ◽  
Fly Ash Concrete ◽  
Chloride Attack

In order to consider the durability of fly ash concrete against the chloride attack, quantitative evaluation of rebar corrosion rate in concrete is necessary. In this study, reinforced concrete specimens containing premixed chlorides were prepared, using concrete with cement or fine aggregate partly substituted by fly-ash. The corrosion rate of rebar embedded in the specimen was evaluated by measuring the polarization resistance which is an electrochemical corrosion index and one of the non-destructive techniques. As a result, the corrosion rate of rebar was greatly suppressed by admixing fly-ash at the environmental temperature of 20 degrees Celsius, while such suppression effect decreased with the rise of temperature to 40 degrees Celsius. The suppression effect was remarkable in the case of fly ash addition as the substitution of fine aggregate. Moreover, in the experimental conditions of this study, the influence of a variation of the chloride content in concrete on the corrosion rate of steel in concrete was not so significant. The influence of environmental temperature on the corrosion rate could be evaluated by an existing formula in the case of non-fly ash concrete, but the error became relatively high in the cases of fly ash concrete.

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