Variations in the Short- and Long-Term Characteristics of Bridge Concrete Due to Transportation Techniques

2000 ◽  
Vol 1698 (1) ◽  
pp. 36-44
Author(s):  
Nur Yazdani ◽  
Michael Bergin ◽  
Ghulam Mujtaba
Keyword(s):  
Compressive Strength ◽  
Chloride Ion ◽  
Unit Weight ◽  
Concrete Durability ◽  
Long Term Effects ◽  
Chloride Permeability ◽  
Highway Projects ◽  
Air Content ◽  
Before And After

The short-term effects of pumping on concrete are well documented, although the long-term effects on concrete durability are not known. Pumping of concrete is widely used in large highway projects because of its convenience and economy of placement. Both types of effects were studied through collection and testing of 73 concrete samples from the Florida Department of Transportation (FDOT) bridge construction sites before and after pumping. The tests performed were air content, slump, unit weight, compressive strength, rapid chloride permeability, and water permeability. The air content and the slump of concrete decreased by about 1 percent and 13 mm (0.5 in.) on average, respectively, due to pumping. The unit weight and compressive strength of concrete increased by about 24 kg/m3 (1.5 pcf) and 1.83 MPa (266 psi), respectively, due to pumping. Pumping decreased the water and chloride ion permeabilities in the majority of tested samples. Results show that pumping does not have detrimental effects on concrete properties; in fact, in many cases, it results in stronger, denser, and more durable concrete. Results indicate that pumping can be continued with confidence as a means of concrete placement in FDOT projects.

The Effect of Superplasticizer on Strength and Chloride Permeability of Concrete Containing GGBFS

2013 ◽  
Vol 804 ◽  
pp. 12-16 ◽  
Author(s):  
Shi Yi Zhang ◽  
Ying Fang Fan ◽  
Ning Ning Li
Keyword(s):  
Mechanical Property ◽  
Compressive Strength ◽  
Diffusion Coefficients ◽  
Chloride Ion ◽  
Ion Diffusion ◽  
Chloride Permeability ◽  
Additive Content ◽  
Chloride Ion Penetration ◽  
Chloride Ion Diffusion

The effect of superplasticizer on the mechanical property and chloride permeability of concrete containing GGBFS is investigated in this paper. Compressive and rapid chloride-ion diffusion tests were conducted to determine the axial compressive and chloride-ion diffusion coefficients of GGBFS modified concrete. The tests result indicated that the compressive strength of GGBFS modified concrete with the addition of 2wt. % superplasticizer are further improved at 14 and 28 days. Superplasticizer can significantly enhance the resistance to chloride ion penetration of concrete containing GGBFS with a reasonable additive content at long-term age. The optimum content of superplasticizer is suggested to be 1wt. % to 2wt. % of the cementitous materials.

scholarly journals Feasibility and Enjoyment of Exercise Video Games in Older Adults

2020 ◽  
Vol 4 (Supplement_1) ◽  
pp. 559-559
Author(s):  
Sara Freed ◽  
Briana Sprague ◽  
Lesley Ross
Keyword(s):  
Older Adults ◽  
Video Games ◽  
Game Design ◽  
Long Term Effects ◽  
Short Term ◽  
Qualitative And Quantitative ◽  
Before And After ◽  
Xbox Kinect ◽  
Game Developers

Abstract Interventions using exercise video games, or exergames, have shown short-term cognitive and physical benefits to older adults, though long-term effects are less promising. Enjoyment of exergames may promote exergame use after the intervention period, though little work has examined older adults’ views of exergames before and after gameplay experience. We invited 20 older adults between 65 and 84 years of age (M=73.30, SD=5.95) to play two Xbox Kinect games, Just Dance and Kinect Sports Rivals, for twenty minutes. In our presentation, we will present qualitative and quantitative findings of this pilot study, including findings that older adults reported that they were not likely to play similar exergames in the future and that they did not find the exergames to be more fun compared to other ways of exercising. We will discuss implications for game design and research relevant to game developers, manufacturers, and researchers. Part of a symposium sponsored by Technology and Aging Interest Group.

scholarly journals Eco-Friendly Fired Brick Produced from Industrial Ash and Natural Clay: A Study of Waste Reuse

Materials ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 877 ◽  
Author(s):  
Neslihan Doğan-Sağlamtimur ◽  
Ahmet Bilgil ◽  
Magdalena Szechyńska-Hebda ◽  
Sławomir Parzych ◽  
Marek Hebda
Keyword(s):  
Compressive Strength ◽  
Bottom Ash ◽  
Unit Weight ◽  
Waste Reuse ◽  
Industrial Solid Waste ◽  
Second Stage ◽  
Before And After ◽  
Fired Bricks ◽  
Two Stages ◽  
And Storage

Bottom ash (BA) is an industrial solid waste formed by the burning of coal. The environmental problems and storage costs caused by this waste increase with every passing day. In this study, the use of BA as an additive (clay substitute) in fired brick production was investigated. The study consisted of two stages. In the first stage, cylinder blocks were produced from clay used in brick production. The second stage was the examination of the experimental substitution of clay with 10, 20, 30 and 40% BA. Samples were fired at 900, 1000, 1100 and 1150 °C to produce fired brick samples. The unit weight, compressive strength (before and after freeze–thawing) and water absorption were analyzed for the samples. The unit weight values decreased in the samples containing BA. The mechanical properties met the conditions prescribed in the relevant standards; i.e., all of the samples fired at 1100 and 1150 °C had a sufficient compressive strength over 20 MPa. The high potential of fired bricks for the construction industry was proved. BA can be used as a clay substitute, while the developed protocol can be used to effectively produce fired bricks.

Effect of Surface Penetrating Sealer on the Microstructure Properties of Cement-Based Composites

2013 ◽  
Vol 651 ◽  
pp. 245-250
Author(s):  
Tasi Lung Weng ◽  
Wei Ting Lin
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Concrete Durability ◽  
Test Results ◽  
Chloride Permeability ◽  
Durability Test ◽  
Chloride Resistance ◽  
Electron Microscopes ◽  
Scanning Electron Microscopes ◽  
Effect Of Surface

The effect of penetrating sealer on the structure of surface pore, mechanical properties, and durability of cement-based composites was studied. Concrete specimens with various water/cement ratios (w/c=0.35, 0.45, 0.55) were cast and treated surfaced with various amounts of penetrating sealer at different ages. The effect of penetrating sealer on the mechanical properties of concrete was assessed by compressive strength. And, the rapid chloride permeability was also explored to test concrete durability. Test results indicate that the application of penetrating sealer significantly improves concrete compressive strength and chloride resistance. By using scanning electron microscopes observation, the penetrating depth of penetrating sealer can be determined and is about 2 cm. The penetrating sealer in this study may be categorized as deep penetrating sealer.

Change in the rocky reef fish fauna of the iconic Poor Knights Islands Marine Reserve in north-eastern New Zealand over 4 decades

2018 ◽  
Vol 69 (10) ◽  
pp. 1496
Author(s):  
David R. Schiel ◽  
Tony Ayling ◽  
Michael J. Kingsford ◽  
Christopher N. Battershill ◽  
J. Howard Choat ◽  
...  
Keyword(s):  
Reef Fish ◽  
Fish Species ◽  
Marine Reserve ◽  
Fish Fauna ◽  
Rocky Reef ◽  
Long Term Effects ◽  
Before And After ◽  
Negative Effect ◽  
Reef Fish Species

Marine reserves exhibit increases in targeted fish species, but long-term effects on biodiversity are poorly understood. Factors other than reserve status may affect decadal changes, including environmental change. We examined the fish fauna at the iconic Poor Knights Islands over 4 decades (1974–2016) before and after implementation of a no-take marine reserve in 1998. We document a substantial increase in commercially and recreationally targeted Chrysophrys auratus, which was virtually absent before 1994 but by 2016 had reached up to 11 fish per 500m2 (220 per hectare). There were also large changes to the fish community, including the decline of subtropical and coastal wrasses, some species with no change and others that increased significantly. Many declines occurred >20 years before the arrival of abundant C. auratus, suggesting the changes do not represent a trophic cascade. Furthermore, this normally benthic-feeding fish has adopted a mid-water foraging behaviour targeting planktivorous fish. The increase in C. auratus appears to be linked both to reserve status and catch regulations in the wider region. Overall, the data point to long-term environmental fluctuations from the late 1970s having a negative effect on the abundance of more than half the reef fish species at these islands.

The Banco de Avío

2021 ◽  
pp. 442-464
Author(s):  
Eric Van Young
Keyword(s):  
Development Strategy ◽  
Textile Industry ◽  
The State ◽  
Development Bank ◽  
Long Term Effects ◽  
Before And After ◽  
Silver Mining ◽  
Short And Long Term ◽  
Textile Sector

At Alamán’s initiative a law of 1830 established the Banco de Avío, a government-funded development bank for the spurring of industrialization, especially in the textile sector, with which his name has forever been associated. His views of industrialization as a development strategy as opposed to a renewed reliance upon silver mining are discussed, as well as the short- and long-term effects of loans made to textile entrepreneurs and the cronyism employed by Alamán both in organizing the Banco itself and in allotting its capital as loans to industrialists. The state of the textile industry in Mexico before and after the Banco is described.

scholarly journals Alkali-activated concretes based on fly ash and blast furnace slag: Compressive strength, water absorption and chloride permeability

2020 ◽  
Vol 40 (2) ◽  
Author(s):  
Daniela Eugenia Angulo-Ramírez ◽  
William Gustavo Valencia-Saavedra ◽  
Ruby Mejía de Gutiérrez
Keyword(s):  
Compressive Strength ◽  
Blast Furnace ◽  
Fly Ash ◽  
Water Absorption ◽  
Blast Furnace Slag ◽  
Construction Materials ◽  
Chloride Ion ◽  
Chloride Permeability ◽  
Alkaline Activator ◽  
Furnace Slag

Concretes based on alkaliactivated binders have attracted considerable attention as new alternative construction materials, which can substitute Portland Cement (OPC) in several applications. These binders are obtained through the chemical reaction between an alkaline activator and reactive aluminosilicate materials, also named precursors. Commonly used precursors are fly ash (FA), blast furnace slag (GBFS), and metakaolin. The present study evaluated properties such as compressive strength, rate of water absorption (sorptivity), and chloride permeability in two types of alkaliactivated concretes (AAC): FA/GBFS 80/20 and GBFS/OPC 80/20. OPC and GBFS/OPC* concretes without alkaliactivation were used as reference materials. The highest compressive strength was observed in the FA/GBFS concrete, which reported 26,1% greater strength compared to OPC concrete after 28 days of curing. The compressive strength of alkaliactivated FA/GBFS 80/20 and GBFS/OPC 80/20 was 61 MPa and 42 MPa at 360 days of curing, respectively. These AAC showed low permeability to the chloride ion and a reduced water absorption. It is concluded that these materials have suitable properties for various applications in the construction sector.

scholarly journals Normalizing the Abnormal: Do Antipsychotic Drugs Push the Cortex Into an Unsustainable Metabolic Envelope?

2019 ◽  
Vol 46 (3) ◽  
pp. 484-495 ◽  
Author(s):  
Federico E Turkheimer ◽  
Pierluigi Selvaggi ◽  
Mitul A Mehta ◽  
Mattia Veronese ◽  
Fernando Zelaya ◽  
...  
Keyword(s):  
Psychotic Symptoms ◽  
Antipsychotic Treatment ◽  
Long Term Effects ◽  
Extrapyramidal Syndrome ◽  
Before And After ◽  
Cardiac Disorders ◽  
Positive Symptoms Of Psychosis ◽  
The Brain ◽  
Novel Model

Abstract The use of antipsychotic medication to manage psychosis, principally in those with a diagnosis of schizophrenia or bipolar disorder, is well established. Antipsychotics are effective in normalizing positive symptoms of psychosis in the short term (delusions, hallucinations and disordered thought). Their long-term use is, however, associated with side effects, including several types of movement (extrapyramidal syndrome, dyskinesia, akathisia), metabolic and cardiac disorders. Furthermore, higher lifetime antipsychotic dose-years may be associated with poorer cognitive performance and blunted affect, although the mechanisms driving the latter associations are not well understood. In this article, we propose a novel model of the long-term effects of antipsychotic administration focusing on the changes in brain metabolic homeostasis induced by the medication. We propose here that the brain metabolic normalization, that occurs in parallel to the normalization of psychotic symptoms following antipsychotic treatment, may not ultimately be sustainable by the cerebral tissue of some patients; these patients may be characterized by already reduced oxidative metabolic capacity and this may push the brain into an unsustainable metabolic envelope resulting in tissue remodeling. To support this perspective, we will review the existing data on the brain metabolic trajectories of patients with a diagnosis of schizophrenia as indexed using available neuroimaging tools before and after use of medication. We will also consider data from pre-clinical studies to provide mechanistic support for our model.

Effects of Learning on Smooth Pursuit During Transient Disappearance of a Visual Target

2003 ◽  
Vol 90 (2) ◽  
pp. 972-982 ◽  
Author(s):  
Laurent Madelain ◽  
Richard J. Krauzlis
Keyword(s):  
Smooth Pursuit ◽  
Visual Target ◽  
Visual Signals ◽  
Control Group ◽  
Long Term Effects ◽  
Velocity Gain ◽  
Visual Inputs ◽  
Before And After ◽  
Pursuit Velocity

Previous research has demonstrated learning in the pursuit system, but it is unclear whether these effects are the result of changes in visual or motor processing. The ability to maintain smooth pursuit during the transient disappearance of a visual target provides a way to assess pursuit properties in the absence of visual inputs. To study the long-term effects of learning on nonvisual signals for pursuit, we used an operant conditioning procedure. By providing a reinforcing auditory stimulus during periods of accurate tracking, we increased the pursuit velocity gain during target blanking from 0.59 in the baseline session to 0.89 after 8 to 10 daily sessions of training. Learning also reduced the occurrence of saccades. The learned effects generalized to untrained target velocities and persisted in the presence of a textured visual background. In a yoked-control group, the reinforcer was independent of the subjects' responses, and the velocity gain remained unchanged (from 0.6 to 0.63, respectively, before and after training). In a control group that received no reinforcer, gain increased slightly after repetition of the task (from 0.63 to 0.71, respectively, before and after training). Using a model of pursuit, we show that these effects of learning can be simulated by modifying the gain of an extra-retinal signal. Our results demonstrate that learned contingencies can increase eye velocity in the absence of visual signals and support the view that pursuit is regulated by extra-retinal signals that can undergo long-term plasticity.

scholarly journals Early Life Maternal Separation and Maternal Behaviour Modulate Acoustic Characteristics of Rat Pup Ultrasonic Vocalizations

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Jasmine H. Kaidbey ◽  
Manon Ranger ◽  
Michael M. Myers ◽  
Muhammad Anwar ◽  
Robert J. Ludwig ◽  
...  
Keyword(s):  
Maternal Separation ◽  
Low Frequency ◽  
Ultrasonic Vocalizations ◽  
Maternal Behaviour ◽  
Long Term Effects ◽  
Acoustic Characteristics ◽  
Rat Pups ◽  
Before And After ◽  
And Control

AbstractEarly separation of preterm infants from their mothers has adverse, long-term neurodevelopmental consequences. We investigated the effects of daily maternal separation (MS) of rat pups from postnatal days 2–10 (PND2–10) on neurobehavioural responses to brief isolation at PND12 compared with pups receiving controlled handling without MS. Ultrasonic vocalizations (USV) were measured at PND12 during two, 3-minute isolations occurring immediately before and after a 3-minute maternal reunion. There were no significant differences in acoustic characteristics between MS and control animals in the first isolation. However, in the second isolation, MS pups produced a greater proportion of high (~60 kHz) vs low (~40 kHz) frequency calls. During this isolation, control pups made longer and louder low frequency calls compared to the first isolation, whereas MS pups did the opposite. Maternal behaviour of control and MS mothers modulated pup acoustic characteristics in opposite directions; higher maternal care was associated with more low frequency calls in control pups but more high frequency calls in MS pups. We hypothesize that MS results in USV emission patterns reflective of a greater stress response to isolation. This translational model can be used to identify mechanisms and interventions that may be exploited to overcome the negative, long-term effects of MS.

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