Papers by Keyword: Thawing

Abstract: The thickness of the near-surface melting layer of ice is estimated by measuring the melting kinetics of the ice spherical balls, temperature readings of the ice surface, and the bulk ice temperature. The temperature monitoring system is programmed on an Arduino-based controller with thermocouple sensors and non-linear semiconducting thermistors. By the melting front, we consider the near-surface layer where multiple types of structural defects accumulate (owing to the latent heat absorption during melting). The melting front contains "point" defects (e.g. vacancies, interstitials) and macroscopic defects, such as dislocations, cracks, stress and strain fields, and vacancy pores. We also measured positron annihilation lifetime spectra in ice and water at temperatures above -8 °C and up to room temperature. We demonstrate that efficient accumulation of the structural defects in melting ice begins only when some temperature overheating above the melting temperature (+0.1...+0.4 °C) is applied and does not occur at negative temperatures.

Abstract: The article presents the influence of the addition of microsilica, finely divided sodium bentonite and air-entraining admixture for concrete frost-resistance and characteristics of examined concrete pores. Examination of frost-resistance was conducted for 150 cycles of freezing and thawing. For selected series of concrete the examination of the porosity structure of concrete composites was conducted with the use of a device for automatic image analysis and computer program Lucia Concrete. What is more, there was made a designation of: consistency of concrete mix, air content in concrete mix, compression strength, water penetration depth and concrete absorbability.

Abstract: The test make steel cylinder concrete, PVC protection tube cylinder concrete , spray coatings Outside the cylinder concrete and no protective measures on ordinary cylinder concrete in three different strength grade:C25, C35 and C50 , putting in the freeze-thaw cycle in three kinds of environment of 5% sulfate solution, 5% sulfate + 3% chlorine salt solution and distilled water,Analysis of the Research of Ring pressure of the Pile foundation on the influence of the durability of concrete by measuring the concrete of Pile foundation corrosion mass loss before and after freezing and thawing.Experiments show that:the concrete with protective measures almost has no mass losses with the level of pile foundation concrete in the same corrosive environment,that, s to say ,the durability is good.While the unprotected concrete has mass losses after the freeze-thaw action hitches in three kinds of solution,And the largest mass loss is in the mixed solution,the durability is the worst.

Abstract: In order to improve the thawing qualities of fish, a thawing process of high voltage electrostatic field (HVEF) was studied. It was compared with nature thawing on the basis of thawing rate and the fish’s qualities index such as pH, thawing loss, cooking loss and total volatile basic nitrogen (TVB-N). The results showed that the high voltage electrostatic field can improve the thawing rate of fish significantly. Compared with nature thawing, the thawed fish under t HVEF had better qualities such as lower thawing loss and total volatile basic nitrogen (TVB-N). HVEF thawing has advantages, which can be used as a substitute method.

Abstract: Assessment of suitability of mortar intended for reconstruction based on their characteristics, namely basic, hygric and mechanical parameters, chemical analysis and frost resistance, is presented in this paper. Properties of the load bearing structure as well as natural factors were also taken into account in assessing the suitability of the used mortars. Comparative measurements with original historic plaster are done as well. On the basis of the experiments performed, it can be concluded that not only mortar properties but also environment conditions and technology of application as well as load bearing structure characteristics have a great importance to the service life of the repaired parts of historical buildings.

Abstract: Based on the freeze-thawing cycle characteristic of road concrete in cold climatic condition. The objective of this paper was to estimate the practicality of using fly ash discharged from a coal fuel electric plant in Inner Mongolia in concrete pavements. The abrasion resistance of road concrete containing fly ash was studied after suffering freeze-thawing cycles. The results indicate that the coarse aggregates were exposed after freeze-thawing cycle test and the replacement ratio of fly ash has little influence on the abrasion resistance.

Abstract: Experiments were conducted to study the resistance of steel-polypropylene hybrid fiber reinforced concrete (HFRC) to freezing and tharwing. The mix proportions of concrete in strength grade CF40 were designed according to the superposition mix design method, where five mass contents of polypropylene fiber changing in range of 0.3~1.5kg/m³ with 0.3kg/m³ increment while the fraction of steel fiber by volume was constant as 1.0%, and four fractions of steel fiber by volume changing in range of 0.5~2.0% with 0.5% increment while the mass content of polypropylene fiber was kept as 0.9kg/m³. The results show that the steel-polypropylene hybrid fiber can significantly increase the resistance of HFRC to freezing and thawing, the losses of dynamic elasticity modulus and flexural strength of HFRC decrease with the increasing mass content of polypropylene fiber and fraction of steel fiber by volume, there is the coupling effect of enhancing on resistance of HFRC to freezing and thawing by hybrid fibers.

Abstract: This work is aimed at resistance to durability of steel slag concrete containing different kinds of steel slag based on maximum utilization of industrial waste residue. The experimental investigation is conducted to study the resistance property to freezing-thawing of concrete which containing steel slag aggregate (SSA), steel slag powder (SSP) and ground granulated blast furnace slag powder (GSP) respectively. One of the specimens is made of ordinary concrete without steel slag as baseline group, the other three concrete specimens are fabricated with the utilization of SSA, and the replacement level is 25%, in combination with 30% SSP or 30% SSP/20% GSP by total binder content. The durable property of steel slag concrete in this study is freezing-thawing resistance, microscopic properties are analyzed by SEM and XRD tests. Experimental results indicate that the concrete which SSA replacement level is 25%, and in combination with 30% SSP and 20% GSP, resistance property of freezing-thawing is superior to baseline group, total dosage of steel slag achieved to 55%. And the mechanism of combined action by adding steel slag is discussed in this paper.

Abstract: The aim of study is to confirm a new technique that can crush the frozen soil and/or ice block using underwater shock wave generated by the underwater explosion of explosive. This technique can lead to the earlier sowing, which can have the larger harvest because the duration of sunshine increases. Especially, in Hokkaido prefecture, Japan, if the sowing is carried out in April, we can expect to have 150% of harvest in the ordinary season. This technique is effective against the cold regions, for example, Russia, Norway, and Sweden, etc. In order to check about that influence we tried to give an actual frozen soil a shock wave. We could get a result that existence of water layer serves an important role in promotion of thawing by the shock loading to the frozen soil. That role was confirmed from the result of numerical simulation.

Abstract: Silty clay’s disturbed soil samples of were measured to ascertain the correlations between thermal conductivity and dry density or water content in the freezing and thawing conditions and provide a certain reference for soil’s thermal conductivity measurement of underground project in seasonal frozen area in future. The relationship between another variable and thermal conductivity was inquired into through fixing one variable in the test process. Through the test data analysis, the conclusion can be drawn as followed. Keeping dry density unchanged, silty clay’s thermal conductivities in freezing and thawing increase with water contents. When dry densities are different, the growth trends of thermal conductivities are slightly different. In the same moisture content, the relation between dry density and thermal conductivity appears as positive correlation.