Behavior of predried mature concrete beams subject to partial wetting and drying cycles

The presented research focuses on the behavior of predried concrete beams with 2.5 m span subjected to cycles of nonsymmetric wetting and drying. Wetting is induced by partially immersing the specimens in a water basin. The submerged portion of the specimens was relatively low (1/5 to 1/10 of their height) leading to a highly nonuniform and nonsymmetric distribution of eigenstrains due to concrete swelling. Unlike conventional experiments on the volume changes of concrete, the measured quantity is not the axial deformation but the vertical displacement instead. This paper presents the experimental data obtained within two wetting and drying cycles, running over 1 year

Micromechanical Analysis of Cement Paste with Carbon Nanotubes

Carbon nanotubes (CNT) are an attractive reinforcement material for several composites, due to their inherently high strength and high modulus of elasticity. There are controversial results for cement paste with admixed CNT up to 500 µm in length. Some results show an increase in flexural or compressive strength, while others showing a decrease in the values. Our experiments produced results that showed a small increase in fracture energy and tensile strength. Micromechanical simulations on a CNT-reinforced cement paste 50×50 µm proved that CNT clustering is the crucial factor for an increasein fracture energy and for an improvement in tensile strength

Invertebrates of the Macocha Abyss (Moravian Karst, Czech Republic)

The invertebrates of the Macocha Abyss, Moravian Karst, Czech Republic, were collected in 2007–2008 and 222 species were identified in total. The relative abundance of individual taxa of land snails, harvestmen, pseudoscorpions, spiders, millipedes, centipedes, terrestrial isopods, beetles, and ants was evaluated. The cold-adapted mountain and subterranean species inhabit the bottom and lower part of the abyss, whereas the sun-exposed rocky margins were inhabited by thermophilous species. Macocha harbors several threatened species that are absent or very rare in the surrounding habitats. In the forest landscape, the Macocha Abyss represents a natural habitat with a distinct microclimatic gradient, and is an excellent refuge area for psychrophilous as well as thermophilous species, which significantly contributes to maintenance of landscape biodiversity.Key words: Ants, centipedes, beetles, biodiversity, harvestmen, land snails, light hole, millipedes, pseudoscorpions, terrestrial ispods, spiders.Nevretenčarji brezna Macoha (Moravski kras, Republika Češka)Med vzorčenjem v letih 2007 in 2008 smo v jami Macoha določili 222 vrst nevretenčarjev. Ovrednotili smo relativno pogostost posameznih taksonov polžev, suhih južin, paščipalcev, pajkov, stonog, kopenskih enakonožcev, hroščev in mravelj. Na mraz prilagojene gorske in podzemeljske vrste naseljujejo dno in spodnji del brezna, toploljubne vrste pa naseljujejo kamnite površine soncu izpostavljenega roba. V Macohi je več ogroženih vrst, ki jih sicer v okoliški pokrajini ne najdemo. Kot habitat s specifično mikroklimo je Macoha izjemno zatočišče za vlagoljubne in toploljubne vrste, ki pomembno prispevajo k vzdrževanju biotske raznovrstnosti v pokrajini.Ključne besede: Mravlje, stonoge, hrošči, suhe južine, kopenski polži, stonoge, psevdoškorpijoni, kopenski enakonožci, pajki, biotska raznovrstnost

A WEAK ALKALI BOND IN (N, K)–A–S–H GELS: EVIDENCE FROM LEACHING AND MODELING

The alkali bond in (N, K)–A–S–H gels presents an up-to-date insufficiently resolved issue with significant consequences for efflorescence in alkali-activated materials. A series of experiments shows nearly all alkalis are leachable from alkaliactivated fly-ash and metakaolin in excessive amounts of deionized water. A diffusion-based model describes well the alkali leaching process. Negligible changes of the (N, K)–A–S–H gel nanostructure indicate that Na,K do not form the gel backbone and H3O+ is probably the easiest substitution for the leached alkalies. Small changes in the long-term compressive strength of leached specimens support this hypothesis

SIZE EFFECT ON THE ULTIMATE DRYING SHRINKAGE OF CEMENT MORTAR: 1-YEAR EXPERIMENT AND NUMERICAL MODELING

The magnitude and time evolution of shrinkage are influenced by numerous factors which are implemented in the design codes often in a different way. The time-dependent behavior of concrete in structures sensitive to creep and shrinkage should be verified by means of short-term laboratory measurements. Extrapolation of drying shrinkage from short-term measurements is an illposed problem. The process is extremely slow but can be accelerated by reducing the specimen size. The knowledge of the size-effect on drying shrinkage is a necessity to establish the transition from the laboratory to the structural size. In the literature, the experimental data on such size-effect are insufficient. For this reason a new experiment was developed to study this phenomenon on small-scale specimens made of cement mortar and the results from the first year are summarized in this paper. The measured data are validated by coupled FEM hygro-mechanical simulations

Dry Separation of Brown Coal Fly Ash, Determination of Properties of Separated Parts, and Their Application in High Volume Cementitious Pastes

The dry separation of brown coal fly ash of density 2.21 g/cm3, specific surface area 5112 cm2/g, having d50 and d97 of 60 and 231 µm was carried out in this research using ultrafine air classifier. Classifiers wheel speed was increased from 2000 to 10000 rpm to obtain fine and coarse products. Median diameter of 5.62 µm was obtained for fine products at a speed of 10000 rpm with nearly 90% decrease in median particle size as compared raw fly ash. Particle morphology was observed on optical, electron microscopes which showed that at 10000 rpm classifiers wheel speed, average fine particles morphology changed from angular and rounded slaggy particles to spherical particles. Cement – 60% fine products samples showed an increase of 26% of compressive strength at 90 days as compared to raw fly ash and linear relationship was developed between median diameter of fines and compressive strength

Perbedaan Fungsi-Fungsi Public Relations Dalam Sosialisasi Pemilihan Kepala Daerah (Pilkada) “Kasus Di KPUD YOGYAKARTA Dan KPUD Bantulâ€

This research attempts to analyze the differences of Public Relations (PR) function in local election (Pilkada). Pilkada is a democratic process in Indonesia. Government needs big participation of society, as one successful point of pilkada is participation of society. Effort to bring public politics participation cannot be separate from politics socialization process. Socialization process is public attitude establishment and politics orientation process. Pilkada socialization carried out by KPUD (Komisi Pemilihan Umum Daerah) as executor. To make an effective socialization to public, KPUD needs to use specific function called Public Relation. Communication activity between organization and its public divided into some part of PR function, including publicity, advertising, press agentry, lobbying, issue management, investor relation and public affair. Basically, implementation of PR function in the process of PILKADA may be different in each region. It becomes the reason why author want to compare KPUD Yogyakarta and Bantul. Governance system differences among both regions would affect in government’s socialization policy. Those differences depend on population, social classes, demographic condition and personal motivation. It is also effecting in PR function held by government, as in media and in society as target operatio

Directional trends in species composition over time can lead to a widespread overemphasis of year‐to‐year asynchrony

Questions: Compensatory dynamics are described as one of the main mechanisms that increase community stability, e.g., where decreases of some species on a year‐to‐year basis are offset by an increase in others. Deviations from perfect synchrony between species (asynchrony) have therefore been advocated as an important mechanism underlying biodiversity effects on stability. However, it is unclear to what extent existing measures of synchrony actually capture the signal of year‐to‐year species fluctuations in the presence of long‐term directional trends in both species abundance and composition (species directional trends hereafter). Such directional trends may lead to a misinterpretation of indices commonly used to reflect year‐to‐year synchrony. Methods: An approach based on three‐term local quadrat variance (T3) which assesses population variability in a three‐year moving window, was used to overcome species directional trend effects. This “detrending” approach was applied to common indices of synchrony across a worldwide collection of 77 temporal plant community datasets comprising almost 7,800 individual plots sampled for at least six years. Plots included were either maintained under constant “control” conditions over time or were subjected to different management or disturbance treatments. Results: Accounting for directional trends increased the detection of year‐to‐year synchronous patterns in all synchrony indices considered. Specifically, synchrony values increased significantly in ~40% of the datasets with the T3 detrending approach while in ~10% synchrony decreased. For the 38 studies with both control and manipulated conditions, the increase in synchrony values was stronger for longer time series, particularly following experimental manipulation. Conclusions: Species’ long‐term directional trends can affect synchrony and stability measures potentially masking the ecological mechanism causing year‐to‐year fluctuations. As such, previous studies on community stability might have overemphasised the role of compensatory dynamics in real‐world ecosystems, and particularly in manipulative conditions, when not considering the possible overriding effects of long‐term directional trends

LOTVS: a global collection of permanent vegetation plots

Analysing temporal patterns in plant communities is extremely important to quantify the extent and the consequences of ecological changes, especially considering the current biodiversity crisis. Long-term data collected through the regular sampling of permanent plots represent the most accurate resource to study ecological succession, analyse the stability of a community over time and understand the mechanisms driving vegetation change. We hereby present the LOng-Term Vegetation Sampling (LOTVS) initiative, a global collection of vegetation time-series derived from the regular monitoring of plant species in permanent plots. With 79 data sets from five continents and 7,789 vegetation time-series monitored for at least 6 years and mostly on an annual basis, LOTVS possibly represents the largest collection of temporally fine-grained vegetation time-series derived from permanent plots and made accessible to the research community. As such, it has an outstanding potential to support innovative research in the fields of vegetation science, plant ecology and temporal ecology