Alkali-aggregate reactivity in Newfoundland, Canada

2000 ◽  
Vol 27 (2) ◽  
pp. 192-203 ◽  
Author(s):  
D Bragg
Keyword(s):  
Laboratory Testing ◽  
Laboratory Tests ◽  
Construction Material ◽  
Concrete Structures ◽  
Site Investigation ◽  
Field Work ◽  
Concrete Core ◽  
Rock Types ◽  
Petrographic Examination ◽  
Alkali Aggregate Reactivity

Alkali-aggregate reactivity is a chemical reaction that occurs in some concrete structures. This reaction causes expansion and cracking of concrete. It may not be the main cause of premature deterioration; however, it is often the catalyst for other forms of deterioration. Since 1989, field work and laboratory testing for alkali-reactivity has been undertaken on selected aggregate, rock, and concrete core samples throughout Newfoundland. The field work and laboratory tests consisted of an assessment of the bedrock and aggregate sites to determine their quality and quantity for use as construction material; an examination of existing concrete structures to assess their durability with regard to alkali-aggregate reactivity. The site investigation of the concrete structures consisted of noting their date of construction, the rock and aggregate types used, the types of cracking, and the degree and type of deterioration of each structure. Results from laboratory testing, petrographic examination, and visual observation show that certain sedimentary, igneous, and metamorphic rock types may be potentially alkali-reactive, but the reaction may not always be deleterious to the concrete structure.Key words: alkali-aggregate reaction, concrete structures, laboratory tests, petrographic examination, rock types.

Performance of Slag Cement in Hydraulic Cement Concrete

2012 ◽  
Vol 2290 (1) ◽  
pp. 84-88 ◽  
Author(s):  
D. Stephen Lane
Keyword(s):  
Portland Cement ◽  
Transport Properties ◽  
Field Work ◽  
Cementitious Materials ◽  
Slag Cement ◽  
Hydraulic Cement ◽  
Insufficient Amount ◽  
Petrographic Examination ◽  
Alkali Aggregate Reactivity ◽  
Virginia Department

The Virginia Department of Transportation began to allow the use of slag cement in hydraulic cement concretes in 1985; its use has steadily increased since then. Several years ago a study was conducted to investigate the performance of bridge decks constructed with hydraulic cement concretes containing straight portland cement and portland cement plus slag cement with a specified water–cementitious materials ratio of 0.45. At the time of the field work, these decks were 12 to 16 years old. In addition to general observations of deck condition, cores were extracted from the decks for petrographic examination of internal condition and determination of concrete transport properties by using electrical conductivity and rate of water absorption. Overall, the slag cement concretes performed well with a tendency toward lower transport properties and showed no inherent tendency for scaling. Some evidence of alkali–aggregate reactivity was observed with evident damage in one case, although it was not clear whether an insufficient amount of slag cement was used or slag cement would simply be ineffective in this case. Overall, the performance and experience with slag cement were favorable.

scholarly journals LABORATORY TESTING OF LEICA AT401 LASER TRACKER

2016 ◽  
Vol 56 (2) ◽  
pp. 88 ◽  
Author(s):  
Filip Dvořáček
Keyword(s):  
Laboratory Testing ◽  
Laboratory Tests ◽  
Angle Measurement ◽  
Distance Measurement ◽  
Additive Constant ◽  
Laser Tracker ◽  
Simple Test ◽  
Absolute Distance ◽  
Warm Up ◽  
The Stability

<p>This paper describes laboratory tests on a Leica AT401laser tracker. As the newer Leica AT402 model also uses the same firmware package, most of the results should also be valid for this device. First, we present the instrument’s firmware errors and the software used for testing. The ASME B89.4.19-2006 standard for testing laser trackers is briefly presented. The warm-up effect of the instrument is inspected with respect to both angle measurement and distance measurement. The absolute distance meter (ADM) is compared with a laboratory interferometer on a 30-meter long rail and also on a bench with automated movement of the carriage of the reflector. A time series of measurements for determining the additive constant is evaluated. A simple test of the stability of the distance measurement in field conditions is introduced. Most of the tests were carried out at the Research Institute of Geodesy, Topography and Cartography (RIGTC) and at the Faculty of Civil Engineering (FCE) of the Czech Technical University in Prague (CTU).</p>

XXV.—Metamorphism in Relation to Structure in the Scottish Highlands

1931 ◽  
Vol 56 (3) ◽  
pp. 621-646 ◽  
Author(s):  
Gertrude Lilian Elles ◽  
Cecil Edgar Tilley
Keyword(s):  
Field Work ◽  
Geological Survey ◽  
Careful Study ◽  
Metamorphic Condition ◽  
Scottish Highlands ◽  
Rock Types ◽  
Long Time ◽  
Metamorphic Zone ◽  
Hand Specimen

The main object of tho present paper is the consideration of the structure of the Central and S.W. Highlands as shown up by the metamorphic condition of the beds. This metamorphic condition has boon studied over the length and breadth of the country, mapped and deduced from very many outcrops in all districts. Sometimes it was possible to superpose the the details respecting the metamorphism upon the 1-inch maps of the Geological Survey, but in many other cases the areas were mapped upon the 6-inch scale. Naturally this work has taken a long time, for it has necessitated the collection of many thousands of specimens, and nearly 3000 rocks have been sliced and examined, since it is not always possible to define the limits of a metamorphic zone with precision by field work alone, and many rock types were encountered that rendered a more careful study advisable than was possible from the mere examination of a hand specimen.

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 Efficiency over thoroughness in laboratory testing decision-making in primary care: findings from a realist review

BJGP Open ◽  
2020 ◽  
pp. bjgpopen20X101146
Author(s):  
Claire Duddy ◽  
Geoff Wong
Keyword(s):  
Primary Care ◽  
Decision Making ◽  
Laboratory Testing ◽  
Laboratory Tests ◽  
Secondary Data ◽  
Realist Review ◽  
Future Research ◽  
Underlying Causes ◽  
Important Means ◽  
Test Ordering

Background: Existing research demonstrates significant variation in test-ordering practice, and growth in the use of laboratory tests in primary care. Reviews of interventions designed to change test-ordering practice report heterogeneity in design and effectiveness. Improving understanding of clinicians’ decision making in relation to laboratory testing is an important means of understanding practice patterns and developing theory-informed interventions. Aim: To develop explanations for the underlying causes of patterns of variation and increasing use of laboratory tests in primary care and make recommendations for future research and intervention design. Design and setting: Realist review of secondary data from primary care. Method: Diverse evidence including data from qualitative and quantitative studies was gathered via systematic and iterative searching processes. Data was synthesised according to realist principles to develop explanations accounting for clinicians’ decision-making in relation to laboratory tests. Results: 145 documents contributed data to the synthesis. Laboratory test ordering can fulfil many roles in primary care. Decisions about tests are incorporated into practice heuristics and tests are deployed as a tool to manage patient interactions. Ordering tests may be easier than not ordering tests in existing systems. Alongside high workloads and limited time to devote to decision-making, there is a common perception that laboratory tests are relatively inconsequential interventions. Clinicians prioritise efficiency over thoroughness in decision-making about laboratory tests. Conclusions: Interventions to change test-ordering practice can be understood as aiming to preserve efficiency or encourage thoroughness in decision-making. Intervention designs and evaluations should consider how testing decisions are made in real-world clinical practice.

scholarly journals Alopecia and Iron Deficiency: An Interventional Pilot Study in Primary Care to Improve the Request of Ferritin

2020 ◽  
Vol 2020 ◽  
pp. 1-6
Author(s):  
Maria Salinas ◽  
Maria Leiva-Salinas ◽  
Emilio Flores ◽  
Maite López-Garrigós ◽  
Carlos Leiva-Salinas
Keyword(s):  
Primary Care ◽  
General Practitioner ◽  
Pilot Study ◽  
Iron Deficiency ◽  
Laboratory Testing ◽  
Laboratory Tests ◽  
Young Female ◽  
Cross Sectional ◽  
Primary Care Patients ◽  
Cross Sectional Studies

Background. The aim was to study the demographic and laboratory pattern of primary care patients with alopecia undergoing laboratory testing, more specifically, the request of hemoglobin and ferritin and values showing anemia and iron deficiency, and to evaluate the effects of an intervention involving automatic ferritin registration and measurement when not requested. Methods. Retrospective and prospective observational cross-sectional studies were conducted, as well as an intervention to automatically register and measure ferritin when not requested by the general practitioner. Results. There were 343 and 1032 primary care laboratory requests prompted by alopecia in the retrospective and prospective studies. Hemoglobin was requested in almost every patient and ferritin in 88%. 5% of the cohort had anemia, and 25% had iron deficiency. The intervention registered and measured that 123 ferritin and 24 iron deficiencies were detected in patients with alopecia, all women, at a cost of 10.6€. Conclusion. Primary care patients with alopecia and laboratory tests request were mainly young female. Our intervention added ferritin when not requested, detecting iron deficiency in 27.9% of women, potentially avoiding the adverse effects of iron deficiency on hair loss.

scholarly journals Detecting radiolaria in the field

1991 ◽  
Vol 10 (1) ◽  
pp. 22-22 ◽  
Author(s):  
Simon K. Haslett ◽  
Paul D. Robinson
Keyword(s):  
Rock Type ◽  
Fine Fraction ◽  
Field Work ◽  
Coarse Mesh ◽  
Extraction Techniques ◽  
The Past ◽  
Fine Mesh ◽  
Rock Types ◽  
Siliceous Rock ◽  
Calcareous Microfossils

Abstract. Radiolaria can be preserved in all types of marine sedimentary rocks, the method for their extraction being dependent on the mineralogy of the radiolarian test and the nature of the rock-type in which they occur. In the past radiolaria could only be viewed in thin section (Hinde, 1890; Hinde &amp; Fox, 1895), with no method of detecting the presence of radiolaria prior to sectioning. Modern extraction techniques are normally laboratory based and use hazardous chemicals, therefore it is advantageous to establish the radiolarian content of the sample before collection and transportation back to the laboratory. This can be achieved in a number of ways:-1. Non-lithified sediments. Radiolaria are separated from the sediment by washing the sample over a set of small sieves. Two mesh sizes should be used, a coarse mesh around 150μm to separate large litho-fragments, and a fine mesh no greater than 63μm to concentrate the radiolaria. The fine fraction is then washed with dilute hydrochloric acid (HCl) to eliminate the calcareous microfossils, leaving a pure radiolarian sludge, which is dried on filter paper.2. Siliceous rock-types. Methods for extracting radiolaria from cherts have been in use since the early 1970’s (Dumitrica, 1970; Pessagno &amp; Newport, 1972), and have recently been applied to field-work (Cordey &amp; Krauss, 1990). The recognition of fossiliferous bedded cherts is possible with the use of a hand-lens in good sunlight. If radiolaria are present, they should be detectable as small protrusions, especially along laminae. To extract the radiolaria, break up the sample. . .

scholarly journals Geotechnical and Minerology Properties of Marine Clay at the Northeast of Penang Island

2018 ◽  
Vol 203 ◽  
pp. 04005
Author(s):  
Nik Mohd Kamel Nik Hassan ◽  
Suhaizan Wahid ◽  
Mohd Taha Abd Wahab
Keyword(s):  
Laboratory Tests ◽  
Soft Clay ◽  
Field Work ◽  
Design Parameters ◽  
Marine Clay ◽  
Commercial Development ◽  
Cone Penetration Tests ◽  
Subsurface Investigation ◽  
Two Phases ◽  
Clay Layers

A series of subsurface investigation including in-situ and laboratory tests has been carefully planned and executed for a proposed residential and commercial development over soft marine clay at Tg Tokong, Penang Island. This paper presents the approach taken in determining and developing fundamental geotechnical engineering design parameters of the soft clay. The subsurface investigation was carried out in two phases to suit the overall development implementation plan namely subsurface investigation done near-shore with about 70 nos of boreholes, 50 nos of cone penetration tests (CPT) and 100 nos of Mackintosh probes and those that were carried out off-shore with 72 Nos of boreholes. The samples extracted from the field work were subjected to grain size analyses, Atterberg limits, oedometer test and consolidated undrained compression. Subsequently, correlations were established between physical soil properties with undrained shear strength from field vane and laboratory tests. The subsurface investigation has suggested that the soft marine clay at the northeast of Penang island comprises of a very soft upper marine clay layer overlying a stiffer lower marine clay. An intermediate stiff clay is sandwiched between these two marine clay layers. The soft clay was also subjected to x-ray diffraction to observe the minerology make up. The primary clay mineral was kaolinite/chlorite followed by smectite. The clay is anticipated to pose minimum effect onto the swelling and compression behaviour.

Strength and Deformation of Bendable Plastic-Concrete-Tubal Structures

2019 ◽  
Vol 974 ◽  
pp. 589-595
Author(s):  
Alexander V. Dolzhenko ◽  
Andrey E. Naumov ◽  
Andrey V. Shevchenko ◽  
N.A. Simonov
Keyword(s):  
Triaxial Compression ◽  
Concrete Structures ◽  
Labor Costs ◽  
Plastic Tube ◽  
Concrete Core ◽  
Metal Structures ◽  
Plastic Concrete ◽  
Steel Consumption ◽  
Strength And Deformation ◽  
The Cost

In modern construction production, structures with the use of tube concrete elements are increasingly used [1]. The use of such structures can significantly reduce the weight of the building, as well as reduce the cost of construction and installation works by 2-3 times compared with similar structures made of classical reinforced concrete. At the same time, labor costs are reduced by 4–5 times. In comparison with metal structures, the cost is significantly reduced and the steel consumption is reduced by a factor of 2–3 with a slight increase in weight. Currently in our country the use of tube concrete structures is not widespread due to insufficient study of their work under various influences. The tube in tube concrete structures simultaneously plays the role of a shell, as well as longitudinal and transverse reinforcement. For a classic tube concrete, the tube is able to perceive the resulting forces from different angles and in all directions. Concrete in the plastic tube, being in conditions of triaxial compression and withstands stresses considerably exceeding the cube and prism strength of concrete. In such structures, the tube prevents the formation of microcracks in the concrete core.

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