scholarly journals Petrographic analysis of carbonate rocks for alkali-aggregate reactivity

1970 ◽  
Vol 14 ◽  
pp. 15-20
Author(s):  
Naresh Kazi Tamrakar ◽  
Lalu Prasad Paudel
Keyword(s):  
Rock Sample ◽  
Rock Type ◽  
Significant Proportion ◽  
Carbonaceous Material ◽  
Petrographic Analysis ◽  
Rock Types ◽  
Alkali Silica Reactivity ◽  
Alkali Carbonate ◽  
Alkali Aggregate Reactivity

Quality of aggregate is of extreme concern when it is to be used for infrastructures. Besides, many physical and mechanicalproperties of the aggregate, presence or absence of deleterious constituents and alkali-silica reactivity are especially importantwhen aggregates are to be used in concrete structures. High potential of alkali-silica reactivity or alkali-carbonate reactivity andpresence of deleterious constituents may impair the infrastructures.A ledge rock sample from the heap to be taken for crushing was petrographically analysed for alkali-silica reactivity. Inoverall, two rock clans (dolosparstone and dolomicrosparstone) with three sub clans (rock type X, Y and Z) from the sample 2 areidentified. Rock type X (dolosparstone) constitutes 82.94% of the whole sample, and shows notable amount of quartz and calciteveins, and carbonaceous material and hematite on the mosaic of dolospars. Rock types Y (dolosparstone) and Z (dolomicrosparstone)contain trace amount of microquartz, mega quartz (>15 mm) and carbonaceous opaques. The rock type Z is dominantly composedof dolomicrospars. Major portions of all the rock types are characterised by mosaics of dolomite in association with variableamounts of muscovite, quartz, and calcite. Calcite often replaces the mosaics of dolomite and bands of quartz, forming a veinnetworks in rock types X and Y. Silica is represented by a low-temperature mega quartz either in ground or in veins, a trace amountof microquartz in rock types Y and Z. There is no other reactive silica components, thus showing a low potential to alkali-silicareactivity. However, the sample shows potential of alkali-carbonate reactivity as significant proportion of rock type havingdolomicrospars are found.DOI: http://dx.doi.org/10.3126/bdg.v14i0.5433Bulletin of the Department of Geology Vol.14 2011, pp.15-20

scholarly journals Petrographic examination of ledge rocks aided by microscopic and X-ray diffraction analyses for alkali-silica reactivity

1970 ◽  
Vol 14 ◽  
pp. 21-28
Author(s):  
Naresh Kazi Tamrakar ◽  
Lalu Prasad Paudel
Keyword(s):  
Rock Sample ◽  
Rock Type ◽  
X Ray Diffraction ◽  
Ledge Rock ◽  
X Ray ◽  
Rock Types ◽  
Alkali Silica Reactivity ◽  
Petrographic Examination ◽  
Type C ◽  
High Quartz

Presence or absence of deleterious constituents and alkali-silica reactivity are especially important when aggregates are to beused in concrete structures. A ledge rock sample was petrographically analysed for alkali-silica reactivity. In overall, two rockclans (metasiltstone and metasandstone) with nine sub clans were identified from the ledge rock sample. All the rock types werewell interlocked, indurated, and cemented extensively by calcite. All the silica grains were low quartz. Except a trace amount ofchert containing microquartz in rock type C, reactive silica such as amorphous silica and high-quartz are absent. Instead, illite inmany rocks and vermiculite in rock types C and D were deleterious silicate components, which in the whole rock sample were5% and 2%, respectively. Presence of vermiculite and illite is found to be strongly controlled by the presence or absence of clayeypartings in metasiltstones and metasandstones.DOI: http://dx.doi.org/10.3126/bdg.v14i0.5435Bulletin of the Department of Geology Vol.14 2011, pp. 21-28

Wadi gravel – a new concrete aggregate in Qatar: Part 2 –Alkali aggregate reactivity

2019 ◽  
Vol 53 (3) ◽  
pp. 400-412 ◽  
Author(s):  
Ian Sims ◽  
Khaled Hassan ◽  
Murray Reid ◽  
Mohammed bin Saif Al-Kuwari ◽  
Mohamed Attia ◽  
...  
Keyword(s):  
Perceived Risk ◽  
Test Methods ◽  
Petrographic Analysis ◽  
Concrete Aggregate ◽  
Gulf Region ◽  
Rock Types ◽  
Alkali Aggregate Reactivity ◽  
Accelerated Mortar Bar Test ◽  
Bar Test ◽  
Mortar Bar

Deposits of Wadi gravel are available in many parts of the Gulf region, but not widely utilized as aggregate for concrete, mainly due to the possibility of internal sulfate attack, plus the perceived risk of alkali aggregate reactivity (AAR). This paper describes the investigations for AAR of the Wadi gravel in this case, as part of the wider study described in Part 1 of this paper.Wadi gravel from the Mekaines site in Qatar was subjected to petrographic analysis, plus the gel-pat and accelerated mortar-bar test methods. The AAR potential was found to be low to normal. The accelerated mortar-bar test exhibited ‘innocuous’ behaviour after 14 days of immersion in alkali solution. When separately testing the constituent rock types of the Wadi gravel, limestone and quartz returned innocuous results, while rhyolite, granite and quartzite returned potentially alkali silica reactive (ASR) results and some reaction was confirmed using post-expansion petrographic examination.Wadi gravel was classified as potentially reactive in the RILEM AAR-4.1 accelerated concrete prism test, but of ‘low reactivity’ in the BS 812-123 test over the longer period of 12 months. Overcoming the potential problems of gypsum content and AAR successfully provides a valuable local resource of Wadi gravel aggregate for concrete.

scholarly journals Intestinal barrier dysfunction in irritable bowel syndrome: a systematic review

2021 ◽  
Vol 14 ◽  
pp. 175628482199358
Author(s):  
Nikita Hanning ◽  
Adam L. Edwinson ◽  
Hannah Ceuleers ◽  
Stephanie A. Peters ◽  
Joris G. De Man ◽  
...  
Keyword(s):  
Quality Of Life ◽  
Systematic Review ◽  
Irritable Bowel Syndrome ◽  
Abdominal Pain ◽  
Barrier Function ◽  
Significant Proportion ◽  
Healthy Controls ◽  
Barrier Dysfunction ◽  
Irritable Bowel

Background and Aim: Irritable bowel syndrome (IBS) is a complex and heterogeneous disorder. Sensory, motor and barrier dysfunctions are the key physiological endophenotypes of IBS. Our aim is to review studies evaluating barrier dysfunction in adults and children with IBS, as well as to link those changes with IBS symptomatology and quality of life. Methods: A comprehensive and systematic review of multiple databases was performed up to March 2020 to identify studies comparing intestinal permeability in IBS patients with healthy controls. Both in vivo and in vitro studies were considered. Results: We identified 66 studies, of which 27 used intestinal probes to quantify barrier function. The prevalence of barrier dysfunction differed between PI-IBS (17–50%), IBS-D (37–62%) and IBS-C (4–25%). At a group level, permeability was increased compared with healthy controls in IBS-D (9/13 studies) and PI-IBS (4/4 studies), but only a minority of IBS-C (2/7 studies) and not in the only IBS-M study. All four studies in children with IBS demonstrated loss of barrier function. A heterogeneous set of tight junction genes were found to be altered in small and large intestines of adults with IBS, but these have not been evaluated in children. Positive associations were identified between barrier dysfunction and bowel disturbances (6/9 studies), abdominal pain (9/13 studies), overall symptom severity (1/6 studies), depression and anxiety (1/1 study) and quality of life (1/4 studies). Fecal slurry or supernatants of IBS patients were found to induce barrier disruption in animal models (5/6 studies). Conclusions: Barrier dysfunction is present in a significant proportion of adult and all pediatric IBS studies, especially in the IBS-D and PI-IBS subtype. The majority of studies indicated a positive association between loss of barrier function and symptoms such as abdominal pain and changes in the bowel function.

scholarly journals Dietary fruits and arthritis

2018 ◽  
Vol 9 (1) ◽  
pp. 70-77 ◽  
Author(s):  
Arpita Basu ◽  
Jace Schell ◽  
R. Hal Scofield
Keyword(s):  
Quality Of Life ◽  
Global Health ◽  
Significant Proportion ◽  
Health Concern

Arthritis is a global health concern affecting a significant proportion of the population and associated with reduced quality of life.

Enhanced and Rock Typing-Based Reservoir Characterization of the Palaeocene Harash Carbonate Reservoir-Zelten Field-Sirte Basin-Libya

2021 ◽  
Author(s):  
Mohamed Masoud ◽  
W. Scott Meddaugh ◽  
Masoud Eljaroshi ◽  
Khaled Elghanduri
Keyword(s):  
Rock Type ◽  
Carbonate Reservoir ◽  
Classification Model ◽  
Reservoir Rocks ◽  
The Core ◽  
Core Samples ◽  
Rock Types ◽  
Rock Typing ◽  
Open Hole ◽  
Type Classification

Abstract The Harash Formation was previously known as the Ruaga A and is considered to be one of the most productive reservoirs in the Zelten field in terms of reservoir quality, areal extent, and hydrocarbon quantity. To date, nearly 70 wells were drilled targeting the Harash reservoir. A few wells initially naturally produced but most had to be stimulated which reflected the field drilling and development plan. The Harash reservoir rock typing identification was essential in understanding the reservoir geology implementation of reservoir development drilling program, the construction of representative reservoir models, hydrocarbons volumetric calculations, and historical pressure-production matching in the flow modelling processes. The objectives of this study are to predict the permeability at un-cored wells and unsampled locations, to classify the reservoir rocks into main rock typing, and to build robust reservoir properties models in which static petrophysical properties and fluid properties are assigned for identified rock type and assessed the existed vertical and lateral heterogeneity within the Palaeocene Harash carbonate reservoir. Initially, an objective-based workflow was developed by generating a training dataset from open hole logs and core samples which were conventionally and specially analyzed of six wells. The developed dataset was used to predict permeability at cored wells through a K-mod model that applies Neural Network Analysis (NNA) and Declustring (DC) algorithms to generate representative permeability and electro-facies. Equal statistical weights were given to log responses without analytical supervision taking into account the significant log response variations. The core data was grouped on petrophysical basis to compute pore throat size aiming at deriving and enlarging the interpretation process from the core to log domain using Indexation and Probabilities of Self-Organized Maps (IPSOM) classification model to develop a reliable representation of rock type classification at the well scale. Permeability and rock typing derived from the open-hole logs and core samples analysis are the main K-mod and IPSOM classification model outputs. The results were propagated to more than 70 un-cored wells. Rock typing techniques were also conducted to classify the Harash reservoir rocks in a consistent manner. Depositional rock typing using a stratigraphic modified Lorenz plot and electro-facies suggest three different rock types that are probably linked to three flow zones. The defined rock types are dominated by specifc reservoir parameters. Electro-facies enables subdivision of the formation into petrophysical groups in which properties were assigned to and were characterized by dynamic behavior and the rock-fluid interaction. Capillary pressure and relative permeability data proved the complexity in rock capillarity. Subsequently, Swc is really rock typing dependent. The use of a consistent representative petrophysical rock type classification led to a significant improvement of geological and flow models.

GEOLOGICAL STUDY AND MINING PLAN IMPORTANCE FOR MITIGATING ALKALI SILICA REACTION IN AGGREGATE QUARRY OPERATION

2016 ◽  
Vol 78 (7-3) ◽  
Author(s):  
Edy Tonnizam Mohamad ◽  
Bhatawdekar Ramesh Murlidhara ◽  
Mohd Nur Asmawisham Bin Alel ◽  
Danial Jahed Armaghani
Keyword(s):  
Aggregate Demand ◽  
Peninsular Malaysia ◽  
Alkali Silica Reaction ◽  
Petrographic Analysis ◽  
Kuala Lumpur ◽  
Developing Regions ◽  
Geological Structures ◽  
Rock Types ◽  
Mine Plan

More than 80 million tonnes of construction aggregate are produced in Peninsular Malaysia. Majority of construction aggregate are produced from granite. Developing regions of Johor Bahru, Kuala Lumpur, Penang and Selangar utilize granite aggregates. Normally it is considered aggregates as non-alkali reactive. Geological study can identify various rock types, geological structures, and reactive minerals which contribute to Alkali Silica Reaction (ASR). Deformed granites formed through faulting results in reduction of quartz grain size. Microcrystalline quartz and phyllosilicates are found in granites in contact with country rocks. Secondary reactive minerals such as chalcedony and opal may be found in granite. Alkali Silica reaction is slow chemical reaction in concrete due to reactive silica minerals in aggregates, alkalis in cement and moisture. For long term durable concrete, it is essential to identify potential alkali silica reactive aggregates. Lack of identifying reactive aggregates may result spalling, cracking in concrete and ultimately ASR can result in hazard to concrete structure. This paper deals with geological study of any aggregate quarry to identify rock type and geological structures with laboratory test –petrographic analysis and bar mortar test can identify type of aggregates being produced. Mine plan with Surpac software can be developed for systematic working for aggregate quarry to meet construction aggregate demand.

scholarly journals The appropriateness of blood transfusion following primary total hip replacement

2012 ◽  
Vol 94 (3) ◽  
pp. 201-203 ◽  
Author(s):  
PJ Joy ◽  
SJ Bennet
Keyword(s):  
Total Hip Replacement ◽  
Hip Replacement ◽  
Orthopaedic Surgery ◽  
Significant Proportion ◽  
Study Data ◽  
Total Hip ◽  
Audit Data ◽  
Prescribing Practice ◽  
Service Data

INTRODUCTION A significant proportion of all red cell transfusions are given to patients undergoing elective orthopaedic surgery. Concern over transfusion safety and cost, coupled with evidence showing that restrictive transfusion policies benefit patients, prompted us to audit our blood prescribing practice at Gloucestershire Hospitals NHS Foundation Trust in order to assess the appropriateness of every transfusion episode following elective primary total hip replacement. METHODS All patients undergoing a primary total hip replacement in our department over a six-month period were included in the study. Data were collected retrospectively using case note examination and transfusion service data. Standards were dictated by the British Orthopaedic Association guidelines on blood conservation in elective orthopaedic surgery. RESULTS Twenty-seven per cent of patients (39/143) were transfused. Forty-six per cent of these (18/39) were transfused inappropriately and twenty-three per cent (9/39) appropriately. Thirteen per cent (5/39) had a valid indication for transfusion but were over-transfused and in eighteen per cent (7/39) the quality of documentation did not allow an assessment to be made. Fifty-two per cent of patients who had surgical drains (29/56) were transfused. Reaudit following staff education and amendments to the local transfusion policy did not demonstrate a reduction in transfusion rates. CONCLUSIONS This audit showed that significant potential exists for reducing transfusion rates based on optimising prescribing practice alone. It also demonstrated that changing local practice based on audit data can be challenging.

scholarly journals Preparation of Thin Sections

1998 ◽  
Vol 6 (7) ◽  
pp. 8-9
Author(s):  
Ian Chaplin
Keyword(s):  
Chemical Composition ◽  
Thin Section ◽  
Microprobe Analysis ◽  
Rock Sample ◽  
Rock Type ◽  
X Rays ◽  
Thin Sections ◽  
Economical Method ◽  
Optical Examination ◽  
Composition Of Minerals

The optical examination of a rock sample in thin section is the quickest and most economical method for classifying rock type and determining which analytical route to follow.Thin sections for transmitted light are the most common, but there are also:Polished Thin Sections • Polished sections are used for classification and identification of minerals that cannot be determined in standard thin sections. They are also essential for microprobe analysis. Minute mineral grains are analyzed by bombarding them with a focused bean of electrons, which generate x-rays, characteristic of the elements within the grains. X-rays are identified and quantified to determine the chemical composition of minerals.

scholarly journals Assessment Gravel Aggregate Reactivity With Alkalis In Relation To Methods Of Test

2014 ◽  
Vol 60 (4) ◽  
pp. 441-452
Author(s):  
Z. Owsiak ◽  
P. Czapik ◽  
J. Zapała-Sławeta
Keyword(s):  
Electron Microscopy ◽  
Deleterious Effect ◽  
X Ray Diffraction ◽  
Chemical Test ◽  
X Ray ◽  
Coarse Aggregates ◽  
Alkali Silica Reactivity ◽  
Alkali Aggregate Reactivity ◽  
Damage In Concrete ◽  
Scanning Electron

AbstractAlkali-aggregate reactivity (AAR) is one of the major causes of damage in concrete. Potential susceptibility of aggregates to this reaction can be determined using several methods. This study compares gravel alkali reactivity results obtained from different tests conducted on coarse aggregates with complex petrography. The potential for the reactivity in the aggregates was revealed in the chemical test using treatment with sodium hydroxide. Optical microscopy, scanning electron microscopy and X-ray diffraction were used to identify the reactive constituents. The expansion measured in the mortar bars test confirmed that the aggregate was potentially capable of alkali silica reactivity with consequent deleterious effect on concrete.

Processes controlling volcanic and epiclastic reservoir formation in a buried polygenetic stratocone

2021 ◽  
pp. SP520-2021-137
Author(s):  
Alan Bischoff ◽  
Jessica Fensom ◽  
Huafeng Tang ◽  
Marcos Rossetti ◽  
Andrew Nicol
Keyword(s):  
Seismic Reflection ◽  
Geothermal Energy ◽  
Mineral Dissolution ◽  
Reservoir Quality ◽  
Petrographic Analysis ◽  
Pore Scale ◽  
Unified Framework ◽  
Mineral Alteration ◽  
Volcanic Terrains

AbstractUnderstanding the formation of volcanic and epiclastic reservoirs is pivotal for exploring geoenergy resources such as geothermal energy, hydrocarbons, and new CO2 sequestration and hydrogen storage opportunities. This paper examines the processes controlling the quality of pyroclastic and epiclastic reservoirs of the Kora volcano, an extinct stratocone presently buried in the offshore Taranaki Basin, New Zealand. We conduct detailed seismic reflection interpretation, drillcore lithofacies and wireline-log description, petrographic analysis, and analytical tests to generate a unified framework that explains the formation of volcaniclastic reservoirs from basin to pore-scale.Each stage of construction and degradation of the Kora volcano is associated with particular processes that increase or reduce reservoir quality. Primary processes include quench fragmentation, deuteric mineral dissolution, and epiclastic sedimentation. Secondary processes comprise mineral alteration (mainly meteoric; minor hydrothermal and diagenetic), mechanical stress fracturing (mainly tectonic; minor magmatic and burial deformation), and pervasive biogenic cementation. Epiclastic conglomerates present the highest reservoir quality (average 23% porosity and up to 997 mD permeability), followed by lapilli-tuffs and tuff-breccias. In contrast, bioclastic epiclastic sandstones are typically cemented by carbonates and pyrite. Our models and interpretations will increase understanding of the formation of volcaniclastic reservoirs and aid exploration of geoenergy resources in volcanic terrains.

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