Evolution of pyrrhotite oxidation in aggregates for concrete
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اقرأ أكثرThe PYRITE guide - Surveyors Journal
Pyrite (FES2 – iron sulphide) is a very common, naturally occurring mineral. Traces of it are naturally found in the sedimentary rock that is used to make crushed stone for backfill used in construction. If the amount of pyrite in the stone is below a certain proportion, no problems occur. However, if it is greater, problems can arise, as ...
اقرأ أكثرDeterioration of residential concrete foundations: The role of ...
Pyrite (FeS2) is commonly present in coarse aggregate, and goethite [FeO(OH)], one of its oxidation products, is observed in many concrete samples. Sulfate ions derived from pyrite oxidation ...
اقرأ أكثرInfluence of internal sulfate attack on cement paste properties ...
1 INTRODUCTION. Internal sulfate attack (ISA) has been considered a serious degradation in concrete structures [1 1 J. Duchesne and B. Fournier, "Deterioration of concrete by the oxidation of sulphide minerals in the aggregate," J. Civ. Eng. Archit., vol. 7, no. 8, pp. 922–931, 2013.The degradation of concrete due to the presence of iron sulfides (such as pyrite and pyrrhotite) in …
اقرأ أكثر(PDF) Aggregates prone to causing pyrite-induced heave …
Following investigation, it was confirmed that the damage was as a result of the use of calcareous mudstone aggregates containing reactive pyrite …
اقرأ أكثرChap05.pdf aggregates for concrete - HOME PAGE CHAPTER 5 Aggregates …
Aggregates for Concrete. bination of gravels or crushed stone with particles. predominantly lar ger than 5 mm (0.2 in.) and generally. between 9.5 mm and 37.5 mm (3 ...
اقرأ أكثرPyrite Mineral | Uses and Properties - Geology
Pyrite has a nickname that has become famous - "Fool's Gold." The mineral's gold color, metallic luster, and high specific gravity often cause it to be mistaken for gold by inexperienced prospectors. ... Crushed stone used to make …
اقرأ أكثرThe swelling properties of certain shales have proven
Approximately 75% of the volume of concrete consists of aggregate; therefore its properties have a significant influence on the engineering behaviour of concrete. Aggregate is divided into coarse and fine varieties, the former usually consists of rock material that passes the 37 mm sieve and is retained on the 4.8 mm sieve.
اقرأ أكثر(PDF) Aggregates for Concrete | Viet Nguyen - Academia.edu
A 2. The aggregate is used in concrete containing more than 297 kilograms of cement per cubic meter (500 lb of cement per cubic yard) when the concrete is not air- entrained. 3. An approved supplementary cementitious material is used to supply the …
اقرأ أكثرPyrite - an overview | ScienceDirect Topics
Pyrite in some aggregates derived from tin mining waste has been involved in the general deterioration of low-grade concrete and concrete building blocks in Cornwall and parts of Devon in the UK. 86–88 However, this so-called 'mundic' problem ('mundic' is the old Cornish word for pyrite) also appears to involve moisture movement ...
اقرأ أكثرInternal attack by sulphates in cement pastes and mortars dosed …
Table 4 Levels of pyrite in relation to the total mass of the aggregate of the base concrete mix proportioning and the cement mass Full size table The studied cement paste was prepared with pozzolanic cement composed in a laboratory with the addition of 20.25% of limestone filler on the weight of the cementitious material (CP V cement + fly ash).
اقرأ أكثرAggregates for Concrete
6.2—Definition of lightweight-aggregate concrete 6.3—Low-density concretes and associated aggregates 6.3.1—Structural lightweight concrete and associated aggregates 6.3.2—Moderate-strength lightweight concrete and associated aggregates 6.3.3—Properties Chapter 7—Recycled aggregates, p. E1-23 7.1—Introduction to recycled aggregates
اقرأ أكثرAlkali-silica reactions in granite-based aggregates: The role of ...
Pyrite dissociates in solutions of pH = 13 and above, into sulphide and iron ions, with potentials of contributing to alkali aggregate reactions. • Biotite and pyrite are both alkali-reactive, thus, potential contributors to AAR. Pyrite predicts a double contribution to concrete degradation: iron ion route and sulphide route. •
اقرأ أكثرCracks due to Defective Concrete Blockwork (Mica / Pyrite)
What causes Defective Blockwork – Pyrite / Mica? Concrete blocks are made of a number of materials including stone aggregate, sand, water & cement. Laboratory testing on similar defects in Counties Mayo & Donegal revealed the presence of muscovite mica and / or pyrite within the constituents of the concrete blockwork.
اقرأ أكثرPyrite in Aggregate| Concrete Construction Magazine
By Concrete Construction Staff Is the presence of pyrite in an aggregate likely to be injurious to concrete? The presence of an appreciable amount of pyrite (iron disulphide) is undesirable, since this compound readily decomposes into weak products such as iron sulphate and limonite, along with the formation of sulfuric acid. About the Author
اقرأ أكثرTesting Structural Concrete Aggregate for Pyrrhotite
Title: Testing Structural Concrete Aggregate for Pyrrhotite
اقرأ أكثرFAQ - Penetron Africa
The result is flat fragments of concrete become detached from the concrete mass by reinforced corrosion. ... as well as producing sulphates that are harmful to concrete. Concrete floors lying on ground that contains Pyrite (Iron (II) Sulphide) are also at risk. Using limestone as the aggregate makes the concrete more resistant to acids, and the ...
اقرأ أكثرEvolution of pyrrhotite oxidation in aggregates for concrete
Evolution of pyrrhotite oxidation in aggregates for concrete. doc zz. Log in ; Registration ; Explore . ×. Evolution of pyrrhotite oxidation in aggregates for concrete ...
اقرأ أكثرInternal attack by sulphates in cement pastes and mortars …
pyrite, it adopts the value of 0.75% pyrite in relation to the aggregate mass [17]; – The Brazilian standard indicates that aggregates con-taining sulphates can be used, provided that the total content, expressed as SO 4 2-, does not exceed 0.1% in mass. If the limit is exceeded, the aggregates may also be used, provided that the content of ...
اقرأ أكثرInfluence of weathering of iron sulfides contained in aggregates …
Introduction The concrete used in some buildings and public works in Maresme, a region near Barcelona (NE Spain), during the period 1970-1972 underwent considerable degradation due to the development of fissures. All the affected concretes contained aggregates from the Mont Palau quarry, which have high contents of iron sulfides, mainly pyrrhotite.
اقرأ أكثرA Brief History of Connecticut s Crumbling Foundations
source of the problem was concrete supplied specifical-ly by a company known as J.J. Mottes, located in Stafford Springs. It was also determined that the source of the aggregate used to produce the concrete was quarried in West Willington at ecker's Quarry. The ecker's Quarry aggregates were used as late as 2014,
اقرأ أكثرEffect of aggregate contamination with pyrite on …
Finally, the research concludes the greater susceptibility of pyrite contaminated concretes with 5.0 of SO3 to the phenomenon of corrosion and the formation of deleterious products, therefore,...
اقرأ أكثرPyrite in the backfill under a concrete slab of a basement …
This swelling is produced by the reaction of pyrite with water, air and moisture. The swelling can cause star cracks and even lift the concrete slab. In a garage, given the greater presence of backfill material, its effect may be more important to make lateral thrusts on the foundation walls of the house, which is rather rare in a basement ...
اقرأ أكثرPyrite in Aggregate - Soil testing engineering - Eng-Tips
There are also a whole new series of test methods as well as a new standard for aggregates for use in concrete. The new standards also include tests for sulphur containing compouds [i.e. pyrite] so this is covered for aggregates for use in concrete as well as engineering fill materials. UK guidance can also be found in the PD 6682 [Parts 1 to 9 ...
اقرأ أكثرThe Effect of Aggregate Properties on Concrete
The Effect of Aggregate Properties on Concrete Concrete is a mixture of cementious material, aggregate, and water. Aggregate is commonly considered inert filler, which accounts for 60 to 80 percent of the volume and 70 to 85 …
اقرأ أكثرThe Consequences of Pyrite Degradation During …
The oxidation of pyrite following exposure of pyrite bearing deposits during earthworks and construction activities has been observed to progress rapidly on a timescale significant to construction, and the process produces conditions that are chemically aggressive to engineering material particularly buried steel and concrete (Reid et al. 2001, 2005; BRE 2001).
اقرأ أكثر(PDF) A comparative investigation of the degradation of pyrite …
A comparative investigation of the degradation of pyrite and pyrrhotite under simulated laboratory conditions
اقرأ أكثرAggregates for Concrete - University of Memphis
aggregates cannot be overemphasized. The fine and coarse aggregates generally occupy 60% to 75% of the concrete volume (70% to 85% by mass) and strongly influ-ence the concrete's freshly mixed and hardened proper-ties, mixture proportions, and economy. Fine aggregates (Fig. 5-1) generally consist of natural sand or crushed
اقرأ أكثرA comparative investigation of the degradation of pyrite and …
The work exposed here is the first step to a more extended study on the role of different iron sulfides when they form part of aggregates used in concrete dams, and has a twofold objective: firstly, to study the oxidation of pyrite and pyrrhotite samples under the same experimental conditions, seeking to differentiate their respective behaviors ...
اقرأ أكثرEffect of aggregate contamination with pyrite on …
The proportional contamination regarding the cement mass was determined by the contamination percentages that were applied over the total mass of aggregates of concrete (2.7 kg of fine aggregate + 2.7 kg of coarse aggregate), according to Table 3. Table 3. Contamination levels. * In relation to the total mass of aggregates.
اقرأ أكثرPyrite - AravenaSorcery
The mineral pyrite or iron pyrite, also known as fool's gold, is an iron sulfide with the chemical formula FeS2 (iron (II) disulfide). Pyrite is considered the most common form of sulfide minerals. Pyrite's metallic luster and pale brass-yellow hue give it a superficial resemblance to gold, hence the well-known nickname of fool's gold. The color has also led to …
اقرأ أكثرUSGS Publishes Map of Potential Pyrrhotite Occurrences
Pyrrhotite, a mineral of concern for the construction industry, consists of iron and sulfur, and when exposed to water and air, it can break down to form secondary minerals that expand and crack concrete, causing concrete structures, like home foundations, to fail. "This project was a bit unusual for us, because typically we're trying to help people find mineral …
اقرأ أكثرRust Coloured Stains on the surface of Exposed Aggregate …
Detailed description of Ironstone deterioration on the surface of concrete The presence of Ironstone in concrete is easily identified. In most cases, the presence of such particles near the surface of Exposed Aggregate will become apparent over a short period of time. The particles themselves are generally dark in appearance and hard to
اقرأ أكثرHow do pyrite and pyrrhotite damage building foundations?
If pyrite or pyrrhotite are present in the aggregate material used to make concrete, the building material itself can be compromised. If water and air get into the concrete through small cracks and holes, the iron sulfides inside can begin to break down, cracking the concrete and allowing more air and water in, causing even more damage.
اقرأ أكثرTolerating Pyrite| Concrete Construction Magazine
The Standard Specification for Concrete Aggregate, ASTM C 33 sets no limits on the amount of pyrite that can be allowed. We do not know of any standard acceptance test for aggregate other than ASTM C 294. Pyrites themselves, when near the surface of concrete, often deteriorate to cause minor popping of the surface and staining.
اقرأ أكثرPyrrhotite and Crumbling Concrete - ct
Aggregate with total sulfur content greater than 1.0% by weight would be prohibited from use in concrete. Aggregate with total sulfur content greater than 0.1% and less than 1.0% by weight would require further …
اقرأ أكثرPPSC49K2019.pdf - Materials: 1. Which component is harmful...
Which component is harmful to bricks Alkali/Iron_pyrite. 2. Which shape of aggregate gives maximum strength Cubical. 3. Coming out of cement slurry from Concrete Bleeding. 4. Cement will be sound if it does not contain free Lime. 5. Suitable stone for construction of pier Granite. 6. Stones are placed in their natural plane so that load acts ...
اقرأ أكثرQUANTIFYING PYRITE AND MICA CONTENTS WITHIN CONCRETE AGGREGATES …
quantifying pyrite and mica contents within concrete aggregates using petrography and whole-rock geochemistry March 2015 International Journal Of Engineering & Applied Sciences 7(1):36-36
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