Resistance of different types of concrete mixtures to sulfuric acid

The present paper is focused on the extraction of gold from high-grade e-waste, i.e., spent electronic connectors and plates, by leaching and electrowinning. These connectors are usually made up of an alloy covered by a layer of gold; sometimes, in some of them, a plastic part is also present. The applied leaching system consisted of an acid solution of diluted sulfuric acid (0.2 mol/L) with thiourea (20 g/L) as a reagent and ferric sulfate (21.8 g/L) as an oxidant. This system was applied on three different high-grade e-waste, namely: (1) Connectors with the partial gold-plated surface (Au concentration—1139 mg/kg); (2) different types of connectors with some of which with completely gold-plated surface (Au concentration—590 mg/kg); and (3) connectors and plates with the completely gold-plated surface (Au concentration—7900 mg/kg). Gold dissolution yields of 52, 94, and 49% were achieved from the first, second, and third samples, respectively. About 95% of Au recovery was achieved after 1.5 h of electrowinning at a current efficiency of only 4.06% and current consumption of 3.02 kWh/kg of Au from the leach solution of the third sample.

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The Utilization of Recycled Masonry Aggregate and Recycled EPS for Concrete Blocks for Mortarless Masonry

Materials ◽

10.3390/ma12121923 ◽

2019 ◽

Vol 12 (12) ◽

pp. 1923 ◽

Cited By ~ 3

Author(s):

Tereza Pavlu ◽

Kristina Fortova ◽

Jakub Divis ◽

Petr Hajek

Keyword(s):

Mechanical Properties ◽

Thermal Properties ◽

Masonry Wall ◽

Expanded Polystyrene ◽

Mechanical And Thermal Properties ◽

Concrete Mixtures ◽

Wall Structures ◽

Different Types ◽

Concrete Blocks ◽

Recycled Masonry

The main aim of this paper is to carry out the environmentally based enhancement of a concrete mixture containing recycled materials whilst considering natural resource consumption as well as mechanical and thermal property levels. The developed concrete is intended to be used in mortarless masonry wall structures. Ten concrete mixtures with different types and replacement rates of recycled masonry aggregate and recycled expanded polystyrene were prepared, and their mechanical and thermal properties were experimentally investigated. It was found that the use of recycled masonry aggregate led to better thermal properties while maintaining sufficient mechanical properties. On the contrary, the addition of recycled expanded polystyrene did not significantly affect the thermal properties of concrete, but the mechanical properties considerably declined. For this reason, the recycled masonry aggregate is suitable to use as an aggregate for concrete masonry blocks for wall structures.

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Shrinkage Behaviour of Fibre Reinforced Concrete with Recycled Tyre Polymer Fibres

International Journal of Polymer Science ◽

10.1155/2015/145918 ◽

2015 ◽

Vol 2015 ◽

pp. 1-9 ◽

Cited By ~ 16

Author(s):

Marijana Serdar ◽

Ana Baričević ◽

Marija Jelčić Rukavina ◽

Martina Pezer ◽

Dubravka Bjegović ◽

...

Keyword(s):

Reinforced Concrete ◽

Drying Shrinkage ◽

Fibre Reinforced Concrete ◽

Restrained Shrinkage ◽

Polypropylene Fibres ◽

Concrete Mixtures ◽

Shrinkage Behaviour ◽

Different Types ◽

Waste Tyre ◽

Recycled Polymer

Different types of fibres are often used in concrete to prevent microcracking due to shrinkage, and polypropylene fibres are among the most often used ones. If not prevented, microcracks can lead to the development of larger cracks as drying shrinkage occurs, enabling penetration of aggressive substances from the environment and reducing durability of concrete structures. The hypothesis of the present research is that polypropylene fibres, used in concrete for controlling formation of microcracks due to shrinkage, can be replaced with recycled polymer fibres obtained from end-of-life tyres. To test the hypothesis, concrete mixtures containing polypropylene fibres and recycled tyre polymer fibres were prepared and tested. Experimental programme focused on autogenous, free, and restrained shrinkage. It was shown that PP fibres can be substituted with higher amount of recycled tyre polymer fibres obtaining concrete with similar shrinkage behaviour. The results indicate promising possibilities of using recycled tyre polymer fibres in concrete products. At the same time, such applications would contribute to solving the problem of waste tyre disposal.

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Experimental research and prediction of the effect of chemical and biogenic sulfuric acid on different types of commercially produced concrete sewer pipes

Cement and Concrete Research ◽

10.1016/j.cemconres.2004.02.015 ◽

2004 ◽

Vol 34 (12) ◽

pp. 2223-2236 ◽

Cited By ~ 130

Author(s):

N. De Belie ◽

J. Monteny ◽

A. Beeldens ◽

E. Vincke ◽

D. Van Gemert ◽

...

Keyword(s):

Sulfuric Acid ◽

Experimental Research ◽

Sewer Pipes ◽

Different Types

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Resistance of different types of concretes to cyclic sulfuric acid and sodium sulfate attack

Cement and Concrete Composites ◽

10.1016/j.cemconcomp.2010.07.002 ◽

2010 ◽

Vol 32 (8) ◽

pp. 595-602 ◽

Cited By ~ 45

Author(s):

F. Girardi ◽

W. Vaona ◽

R. Di Maggio

Keyword(s):

Sulfuric Acid ◽

Sodium Sulfate ◽

Sulfate Attack ◽

Different Types

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Biogenic sulfuric acid attack on different types of commercially produced concrete sewer pipes

Cement and Concrete Research ◽

10.1016/j.cemconres.2009.10.002 ◽

2010 ◽

Vol 40 (2) ◽

pp. 293-301 ◽

Cited By ~ 66

Author(s):

Ma. Guadalupe D. Gutiérrez-Padilla ◽

Angela Bielefeldt ◽

Serguei Ovtchinnikov ◽

Mark Hernandez ◽

Joann Silverstein

Keyword(s):

Sulfuric Acid ◽

Acid Attack ◽

Sewer Pipes ◽

Different Types

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Creep Property of Concretes with Different Types of Coarse Aggregates

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.174-177.308 ◽

2012 ◽

Vol 174-177 ◽

pp. 308-313 ◽

Cited By ~ 1

Author(s):

Yan Jun Liu ◽

Mang Tia

Keyword(s):

Prestressed Concrete ◽

Prediction Models ◽

Creep Property ◽

Cementitious Materials ◽

Prestress Loss ◽

University Of Florida ◽

Coarse Aggregates ◽

Concrete Mixtures ◽

Florida Department ◽

Different Types

The rheological phenomenon of concrete materials, also termed as creep, is one of very important properties of concrete. Excessive deformation caused by creep does more detrimental effects on prestressed concrete structures than otherwise. Even though some investigations had been conducted on the normal concrete mixtures by the researchers and engineers all over the world, and the conclusions and the creep prediction models based on those investigations were developed, their effectiveness to be extended to all the concrete mixtures is very limited due primarily to the susceptibility of the creep property of concrete to the variation of the properties of aggregate, cement, water to cementitious materials ratio and their proportions. Especially for prestress concrete, creep induced prestress loss puts severe threat on the safety and durability of prestressed structures. Thus, in order to thoroughly understand the creep characteristics of the typical concrete mixtures used in Florida, this project was carried out by University of Florida and Florida Department of Transportation. The investigation found out that the creep strains of the concretes with different types of coarse aggregates at 91 days are very close, while the differences of creep coefficients of the concretes with different aggregates are fairly significant.

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Sulfate Attack on Different Types of Concrete in Media Simulating Sewer System

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.714.122 ◽

2016 ◽

Vol 714 ◽

pp. 122-127

Author(s):

Martin Vyšvařil ◽

Markéta Rovnaníková ◽

Patrik Bayer

Keyword(s):

Waste Water ◽

Sulfuric Acid ◽

Sewage Water ◽

Sulfate Attack ◽

Acid Attack ◽

Bottom Part ◽

Sewer Pipes ◽

Fine Grained ◽

Different Types ◽

One Year

The degradation of concrete due to ingress of sulfate ions from the environment plays an important role in the durability of concrete constructions. Microbiologically induced concrete corrosion (MICC) damages especially sewage collection systems. The most rapid cases of deterioration always occur in areas with elevated H2S concentrations, moisture, and oxygen in the atmosphere. During the MICC, the pH of the surface of concrete sewer pipes is reduced and it may lead to the steel depassivation and results in the corrosion of steel reinforcement. Damage due to a sulfate interaction can result in a cracking and softening, with a loss of strength of concrete. The formation of ettringite (AFt) from gypsum (forming by reaction of sulfate anion with calcium hydroxide) and C3A via monosulfate (AFm) is the main chemical reaction of sulfate attack on concrete. Ettringite and gypsum have considerably larger volume than initial compounds, which leads to increased pressure in concrete. This paper is focused on the sulfate attack on fine-grained concrete where the effect of 0.5% sulfuric acid, simulating MICC, and a solution simulating sewage water has been investigated on changes of the pH, content of sulfates and the porosity in various types of concrete. The aim of this study is to compare the changes in different types of concrete during the sulfate attack in two kinds of medium represented the bottom part of pipelines (waste water) and the sewer crown (0.5% H2SO4). It was found, that after 1 year in 0.5% H2SO4, a visible degradation of surface occurs in all investigated types of concrete. Samples over the year in waste water became dark. Concentration of sulfates in all studied types of concrete increased six times at least after one year sulfuric acid attack and also the reduction of the pH of their aqueous leaches was determined. The solution simulating sewage water did not cause such changes.

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Abrasive Wear Resistance of Concrete in Connection with the Use of Crushed and Mined Aggregate, Active and Non-Active Mineral Additives, and the Use of Fibers in Concrete

Sustainability ◽

10.3390/su12239920 ◽

2020 ◽

Vol 12 (23) ◽

pp. 9920

Author(s):

Lenka Bodnárová ◽

Martin Ťažký ◽

Lucia Ťažká ◽

Rudolf Hela ◽

Ondřej Pikna ◽

...

Keyword(s):

Abrasion Resistance ◽

Age Groups ◽

High Strength ◽

Mineralogical Composition ◽

Concrete Mixtures ◽

Standard Procedures ◽

Different Types ◽

The Impact ◽

Mineral Additives ◽

Active Mineral Additives

Virtually every concrete structure comes into contact with abrasive effects of flowing media or solids, which have a direct impact on the durability of concrete. An abrasive effect is most pronounced in transport or water management structures, and these structures are often designed for a significantly longer service life (usually 100 years). This research evaluates the influence of the filler component in terms of the type of aggregate and its mineralogical composition on concrete abrasion resistance. As part of the impact of the binder component, several concrete mixtures were produced using the same aggregate and maintaining the same strength class with the addition of different types of active and inert mineral additives. In other parts of the research, the effect of adding fiber reinforcement on the abrasion resistance of concrete was verified. Mutual connections and correlations in different age groups (7, 28 and 90 days) were sought for all obtained results. The abrasion resistance of the composite was monitored by using standard procedures, especially using a Böhm device. It was found that for good abrasion resistance of concrete, it is not necessary to produce concretes with high strength classes using often expensive mineral additives (microsilica) and quality aggregates, but the maturation time of the composite and its microstructure plays an important role.

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