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Clays as SCM – Reactivity of Uncalcined Kaolinite and Bentonite, and Impact on Phase Assemblage and Strength Development of PC Mortars

Abstract

The impact of substitution of cement paste with uncalcined clay (bentonite and kaolinite) in the range of 5% by volume of paste on the development of hydration and properties of mortar was investigated. Two issues were addressed, the expected filler effect of the dispersed sub-micron clay particles, and the possible chemical reactivity of the clay.

The study indicated that Portland cement paste may be modified by addition of well dispersed clay and that the impact includes accelerated cement hydration as well as altered distribution of products. Compressive strength development was accelerated, but later age strength was reduced, especially for the bentonite mixes. In contrast, microscopic porosity measurements indicated no detrimental impact on the coarse capillary porosity.

The investigation indicates that for durability related engineering properties, the application of uncalcined clay might be a potential means for reduction of the clinker factor in concrete in support of sustainability.

Open access
Comparing Nozzles with Different Wear Rate and Working with the Same Application Rate of Different Plant Protection Products in Aspect of Plants Condition

Abstract

Three different types of nozzles (different wear rate) were used in this study. They are classified depending on the severity of their wear to three groups: new, worn and damaged nozzles. Those nozzles were spraying with the same application rate (303 l/ha) on two-year field trials; this was achieved by changing the spraying pressure for each group of nozzles in order to get the same application rate. This practice is usually done by operators of sprayers, who calibrate the sprayers on the same application rate every year without changing the nozzles, so they tend to reduce the spraying pressure in order to compensate the flow rate increase due to the nozzles yearly wear. Two types of plant growth regulators (PGR) agents were used in this study, namely: Moddus and Kelpak, they were applied to wheat plants field to reduce lodging. The results showed that applying PGR in the year 2015 produced an increase in the wheat yield and reduction in the plant height regardless the nozzle type, although there was not any occurrence of wheat lodging. In the year 2016, the new nozzles produced higher values of wheat yield than other two types of nozzles.

Open access
Comparison of Punching Shear Design in Finland According to the Current and the Former Method

Abstract

In the beginning of 2017 the design method for punching shear in Finland was changed. The method presented in Eurocode 2 was adopted with some nationally determined parameters and rules. During 2016 and 2017 computational analyses were conducted to compare the previous national design method and the new one. Comparison setups were created in which different parameters were varied. The results were presented the predicted punching resistances differ differences are significant and can be almost 60% in some cases.

Open access
Correlation between surface morphology and potential profile in OFETs with zone-cast TIPS-Pentacene as seen by scanning Kelvin probe microscopy

Abstract

Charge-carrier transport in the channel of bottom gate, top contact organic field effect transistors with anisotropic layers of 6,13-bis(triisopropylsilylethynyl) pentacene (TIPS-Pentacene) obtained by zone casting was investigated using scanning Kelvin probe microscopy combined with atomic force microscopy. The TIPS-Pentacene continuous layers consisted of thin crystals unidirectionally oriented in the channel. Devices with perpendicular and parallel charge flow in the transistor channel were prepared. It was found that irregularities in the surface morphology at the semiconductor layer in the transistor channel are correlated with the local potential profile, and that the channel resistance strongly depends on the orientation of the TIPS-Pentacene crystals.

Open access
Corrosion behaviour of the titanium beta alloy nanotubular surface in the presence of fluoride ions

Abstract

The titanium bioactivity could be increased by surface nanostructuring. Titanium alloys are using for dental implants manufacturing. It represents a specific problem because of using of the dental treatments with high concentration of fluoride ions and with acidic pH. The corrosion resistance of nanostructured surface of titanium beta alloy in environments with fluoride ions was examined by common electrochemical technique. The electrochemical impedance measurement showed high corrosion resistance in physiological solution. The fluoride ions have expected negative influence on corrosion behaviour of the layer. The nanotube bottom was preferentially attacked which resulted in layer undercoroding and its detachment.

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Corrosion resistance of AZ31 magnesium alloy treated by plasma electrolytic oxidation

Abstract

The coating prepared by plasma electrolytic oxidation (PEO) was created on AZ31 magnesium alloy surface with the aim to evaluate its effect on corrosion resistance. The DC current was applied on the sample in solution consisted of 10 g/l Na3PO4·12H2O and 1 g/l KOH. Additional samples were prepared with 2 and 4 minutes of preparation to observe evolution of the PEO coating. Morphology of the coatings was evaluated by scanning electron microscopy and chemical composition was examined by EDX analysis. Electrochemical characteristic were measured by potentiodynamic polarization tests and electrochemical impedance spectroscopy in 0.1 M NaCl at the laboratory temperature. Obtained data were presented in form of potentiodynamic curves and Nyquist diagrams. Results of analysis showed that plasma electrolytic oxidation coating positively influence corrosion resistance of AZ31 magnesium alloy in chosen corrosive environment.

Open access
Cracking of the End Diaphragm of a Post-tensioned Beam Bridge

Abstract

In concrete beam bridges, the end diaphragm at the end of the bridge is a common structural component that connects the main beams and transfers the beam loads to the bridge bearings. In integral bridges the end diaphragm also retains the soil of embankments due to the absence of abutments. Cracking of the front surface on the end diaphragm has been detected in post-tensioned beam bridges in Finland and Sweden. Presumably the post-tensioning of the bridge and the shaping and detailing of the connection of the end diaphragm and main beam have an effect on cracking tendency. The aim of this study is to examine the structural behaviour and the cracking potential of end diaphragms using linear analysis of the post-tensioned bridge and to find measures to prevent the cracking.

The observations collected through field surveys are compared to results of linear FE analysis to clarify the cause of the cracking. The verification of model is performed by comparison of patterns of cracking observed in field surveys and the distribution of maximum tensile stresses in the FE model. With model variations, the effectiveness of measures for the prevention of cracking are observed.

Open access
The delocalization of production to Poland

Abstract

This paper presents some aspects of the process of services, products and manufacturing transfer, with the associated production resources, from other locations and plants to Poland.

The study was carried out on the basis of an analysis of publications about delocalization as well as by means of desk research, where there were used the accessible primary and secondary data such as branch reports, statistical data available in reports, data bases, and information accessible on Polish and European websites. The article is also the result of the author's experience of participation in the relocation of a number of international companies, regarding various industries. Delocalization in Poland was presented both from the point of view of Conceptualizing delocalization (literature review, theoretical position) and Implementation of production.

The delocalization mainly takes advantage of labor forces. On the other hand, it may also concern innovative activities and develop high-tech for regions affected by economic restructuring. The social policies for the risk mitigation of the delocalization of production are also being developed and implemented. This work clarifying the conditions of delocalization in Poland and highlight the important roles played by innovation and institutions for achieving sustainability.

Open access
Dielectric properties of Bi-substituted LDHs synthesized by co-precipitation and sol-gel methods

Abstract

Magnesium-aluminum-bismuth layered double hydroxides (Mg3Al1−xBix; LDHs) were prepared using both coprecipitation and sol-gel methods. For the preparation of Mg/Al/Bi LDH by the co-precipitation method, the appropriate amounts of dissolved starting materials (Al(NO3)3 · 9H2O, Mg(NO3)2 · 6H2O and Bi(NO3)3 · 5H2O) were mixed with a solution of NaHCO3:NaOH. In the sol-gel processing, the precursor Mg–Al–Bi–O gels were synthesized using the same starting materials and ethylene glycol as complexing agent. The mixed-metal oxides obtained by subsequent heating of Mg–Al–Bi–O gels at 650 °C were reconstructed to Mg3Al1−xBix LDHs in water at 80 °C. All the synthesized products were characterized by X-ray diffraction (XRD) analysis, scanning electron microscopy (SEM) and dielectric measurements.

Open access
Dynamic magnetoelastic properties of TbxHo0.9−xNd0.1(Fe0.8Co0.2)1.93/epoxy composites

Abstract

TbxHo0.9−xNd0.1(Fe0.8Co0.2)1.93/epoxy (0 ⩽ x ⩽ 0.40) composites are fabricated in the presence of a magnetic field. The structural and dynamic magnetoelastic properties are investigated as a function of both magnetic bias field Hbias and frequency f at room temperature. The composites are formed as textured orientation structure of 1–3 type with 〈1 0 0〉 preferred orientation for x ⩽ 0.10 and 〈1 1 1〉-orientation for x ⩾ 0.25. The composites generally possess insignificant eddy-current losses for frequency up to 50 kHz, and their dynamic magnetoelastic properties depend greatly on Hbias. The elastic modulus (E3 H and E3 B) shows a maximum negative ΔE effect, along with a maximum d33, at a relatively low Hbias ~ 80 kA/m, contributed by the maximum motion of non-180° domain-wall. The 1–3 type composite for x ⩾ 0.25 shows an enhanced magnetoelastic effect in comparison with 0 to 3 type one, which can be principally ascribed to its easy magnetization direction (EMD) towards 〈1 1 1〉 axis and the formation of 〈1 1 1〉-texture-oriented structure in the composite. These attractive dynamic magnetoelastic properties, e.g., the low magnetic anisotropy and d33 , max as high as 2.0 nm/A at a low Hbias ~ 80 kA/m, along with the light rare-earth Nd element existing in insulating polymer matrix, would make it a promising magnetostrictive material system.

Open access