Natural Stone Waste Powders Applied to SCC Mix Design

In order to comply with current trends concerning sustainability, saving of primary materials and energy\ud savings, this paper addresses Eco-concrete. The major focus thereby is on the increased efficiency of cement\ud use. Applying a new mix design method for concrete, cement contents can be decreased and partially be substituted\ud by other fine powders, preferentially by waste powders which have no mass application so far. This\ud paper is giving examples of successfully introduced waste powders and characterizes the concretes produced\ud with these powders. These innovative, low cement concrete types obtain medium strength and exhibit furthermore\ud self-compacting abilities. This paper additionally highlights possibilities for the direct use of natural\ud stone sludges or filter cakes. A new grading based design method, developed in the authors’ research\ud group, enables the efficient use of all materials available. The method is applicable to self-compacting concretes,\ud earth-moist concretes and conventionally vibrated concretes

Late Pliocene Paleoecologic Reconstructions Based on Ostracode Assemblages from the Sagavanirktok and Gubik Formations, Alaskan North Slope

Shallow-marine ostracode assemblages from upper Pliocene sediments of the upper part of the Sagavanirktok Formation and lower part of the Gubik Formation record the last warm period that occurred before the onset of significant cooling of the Arctic Ocean and the initiation of Northern Hemisphere continental glaciation. The informally named Colvillian and Bigbendian transgressions represent the oldest deposits of the Gubik Formation and are dated, based on various lines of evidence, between 2.48 and 3 Ma. Ostracode faunas from the lower part of the Gubik Formation indicate a cold-temperate to subfrigid marine climate with summer bottom temperatures 1-4 C warmer than today. Deposits of the upper part of the Sagavanirktok Formation at Manning Point and Barter Island are older than Colvillian sediments but are believed to be late Pliocene in age and contain an ostracode fauna that has many species in common with the lower part of the Gubik Formation. The Sagavanirktok ostracode faunas indicate a cold-temperature to subfrigid marine climate, similar to that inferred for the lower part of the Gubik Formation, with summer bottom temperatures 1-3 C warmer than today. The opening of Bering Strait at about 3 Ma altered Arctic Ocean assemblage composition as Pacific species migrated into the Arctic and North Atlantic oceans. The admixture of evolutionarily distinct faunas from the Atlantic and Pacific oceans identifies Colvillian (and younger) faunas and provides a convenient reference horizon in the Alaskan fossil record. The marine climatic deterioration that followed the Bigbendian appears to have been abrupt and is documented by biotic turnover, with large numbers of species extinctions and first appearances of new species. The change in species composition can be attributed to the cooling of the Arctic Ocean during the late Pliocene.Key words: Pliocene, ostracode, Sagavanirktok Formation, Nuwok Member, Gubik Formation, Alaska, North Slope, shallow marineDes assemblages d'ostracodes de milieu marin peu profond trouvés dans des sédiments datant du pliocène supérieur et situés dans la couche supérieure de la formation de Sagavanirktok et dans la couche inférieure de la formation de Gubik témoignent de la dernière période tempérée qui a précédé le refroidissement majeur de l'océan Arctique et la glaciation continentale de l'hémisphère boréal. Les transgressions communément appelées colvillienne et bigbendienne représentent les plus anciens dépôts de la formation de Gubik et on les fait remonter, en s'appuyant sur des preuves diverses, à une période située entre 2,48 et 3 Ma. Les faunes d'ostracodes situées dans la couche inférieure de la formation de Gubik témoignent d'un climat marin allant de froid-tempéré à glacial, avec des températures estivales au fond de 1 à 4 °C plus élevées que de nos jours. Les dépôts de la couche supérieure de la formation de Sagavanirktok à Manning Point et à Barter Island sont plus anciens que les sédiments colvilliens, mais dateraient du pliocène tardif et renferment une faune d'ostracodes partageant un grand nombre d'espèces avec la couche inférieure de la formation de Gubik. Les faunes d'ostracodes de Sagavanirktok témoignent d'un climat marin, allant de froid-tempéré à glacial, semblable à celui qui aurait pu exister au moment où commença à se déposer la formation de Gubik, avec des températures estivales au fond de 1 à 3 °C plus élevées que de nos jours. L'ouverture du détroit de Béring il y a environ 3 Ma a changé la composition des assemblages de l'océan Arctique avec la migration dans les océans Arctique et Atlantique Nord d'espèces venant du Pacifique. Le mélange de faunes distinctes sur le plan de l'évolution venant de l'Atlantique et du Pacifique identifie les faunes colvilliennes (et plus récentes) et offre un horizon repère pratique pour le dossier fossile de l'Alaska. Le refroidissement climatique marin qui a suivi l'époque bigbendienne semble avoir été soudain et est confirmé par le renouvellement biotique, avec la disparition d'un grand nombre d'espèces et l'apparition de nouvelles. On peut attribuer le changement dans la variété des espèces au refroidissement de l'océan Arctique durant le pliocène tardif.Mots clés: pliocène, ostracode, formation de Sagavanirktok, membre de Nuwok, formation de Gubik, Alaska, versant Nord, milieu marin peu profon

Social stigma is an underestimated contributing factor to unemployment in people with mental illness or mental health issues:Position paper and future directions

Background As yet, little is known about the effects of mental health stigma on sustainable employment. This is surprising, as mental health stigma is common, and because people with severe and common mental disorders are 7 and 3 times more likely to be unemployed, respectively, than people with no disorders. As the global lifetime prevalence of mental disorders is 29%, the high unemployment rates of people with these health problems constitute an important and urgent public health inequality problem that needs to be addressed. Main text The aim of this position paper is to illustrate the assumption that stigma contributes to the unemployment of people with mental illness and mental health issues with evidence from recent scientific studies on four problem areas, and to provide directions for future research. These four problem areas indicate that: (1) employers and line managers hold negative attitudes towards people with mental illness or mental health issues, which decreases the chances of people with these health problems being hired or supported; (2) both the disclosure and non-disclosure of mental illness or mental health issues can lead to job loss; (3) anticipated discrimination, self-stigma and the ‘Why Try’ effect can lead to insufficient motivation and effort to keep or find employment and can result in unemployment; and (4) stigma is a barrier to seeking healthcare, which can lead to untreated and worsened health conditions and subsequently to adverse occupational outcomes (e.g. sick leave, job loss). Conclusions The paper concludes that stigma in the work context is a considerable and complex problem, and that there is an important knowledge gap especially regarding the long-term effects of stigma on unemployment. To prevent and decrease adverse occupational outcomes in people with mental illness or mental health issues there is an urgent need for high quality and longitudinal research on stigma related consequences for employment. In addition, more validated measures specifically for the employment setting, as well as destigmatizing intervention studies are needed

Water-powder mixtures at the onset of flowing

The knowledge of water demands of the manifold concrete ingredients is of vital interest for the design of concrete mixes. Physical properties like workability or strength and durability in hardened state are controlled by the total water content. Water demand is defined as the volumetric ratio of water to solid material at a certain state, which is defined by the selected test method. Given that powders provide the b far highest percentage of specific surface area in a concrete mixture, their water demand is of special interest. In literature diverse methods for the determination of powders’ water demands can be found. However, it appears that the spread-flow test, sometimes referred to as mini-slump flow test, has achieved general acceptance in concrete technology. In this research the spread-flow test has been analyzed in more detail. In this way new measures are derived which contribute to a deeper understanding of wet granular mixtures at the onset of flowing. The deformation coefficient which will be derived by the spread-flow test was confirmed to correlate with the product of Blaine surface and intrinsic density of the individual powders when the mixture is flowing only under its own weight. Similarly, correlations with equal accuracy have been found with a computed specific surface based on measured particle size distributions instead of the Blaine surface. Using flow experiments it was possible to derive an overall factor for assessing the non-spherical shape of the powder particles. A good correlation of this computation algorithm was derived compared to the standard Blaine method. Finally, a constant water layer thickness around the powder particles was derived for all powders at the onset of flowing. This implies the possibility to predict flow behavior of mortar and concrete mixtures only based on the knowledge of their granular characteristics

Self-cleaning surfaces as an innovative potential for sustainable concrete

Concrete technology is subject of continuous development and improvement. One of the very recent contributions to durability and sustainability of concrete is the self-cleaning ability. This effect is achieved by applying photocatalytic materials to the concrete mix. This paper describes the effect of self-cleaning and air purification. Since about 10 years concrete paving stones, provided with this function, are available. With the development of a test setup and using nitric oxide (NO) as model pollutant an approach was found to quantitatively assess the air-purifying ability of those paving stones. This seems to be of interest since a real comparative analysis of air purifying concrete products is not available and the establishment of a measurement standard for concrete products is still in a draft-state. A brief technical description of this test setup will be presented to the reader. Using this innovative setup, the influences on the degradation efficiency are studied and a basic reaction model is derived

Realist Evaluation : an overview

This report summarises the discussions and presentations of the Expert Seminar ‘Realist Evaluation’ with Gill Westhorp, which took place in Wageningen on March 29, 2011. The Expert Seminar was organised by the Wageningen UR Centre for Development Innovation in collaboration with Learning by Design and Context, international cooperation

Photocatalysis applied to concrete products - part 2 : influencing factors and product performance

The second part of this three-part article series addresses the influence of physicochemical parameters on the degradation performance of concrete products containing photocatalytic active TiO2. The influence of process conditions like irradiance, relative humidity, pollutant concentration and flow rate on the degradation mechanism is investigated. Furthermore, a short overview on photo catalytic powders (especially TiO2) and their influence on the degradation of NO are presented. In addition the application of TiO2 coatings and their microstructural analysis is explained