Evaluation of the Strength Characteristics of Silty-Clayey Soils during Freezing-Thawing Cycles

Destructuring settlements due to frost heave during the structures’ exploitation are often not taken into account at the designing stage, although they are indirectly related to the bearing capacity of the soils. The objective of this research was analyzing the effect of the number of freezing-thawing cycles on the strength characteristics of soils. A paired experiment with various initial parameters (void ratio, initial moisture content, and the number of freezing-thawing cycles) was carried out. According to the experimental results, the cohesion largely depends on the above parameters which might lead to its decrease by up to three times. The angle of internal friction demonstrated an indefinite behavior during the freeze-thaw cycles, which is confirmed by a literature review. Freezing–thawing cycles significantly decrease the soil bearing capacity: up to 44% after 10 freezing-thawing cycles for soil with and . However, in the case of and it increased by 33%. A program based on the least-squares method was used to calculate the approximation coefficients of the dependence describing the changes in strength characteristics from the abovementioned parameters. Changes in strength characteristics must be taken into account when designing structures, as they can lead to additional settlement or even subsidence of the foundations.

Effect of Extrusion Temperature and Feed Moisture Content on the Microstructural Properties of Rice-Flour Pellets and Their Impact on the Expanded Product

Extrusion can lead to an expanded product or to a slightly expanded pellet, known as a third-generation (3G) snack. In this case, expansion occurs subsequently, in an independent thermal device (e.g., oven), out of the extruded pellet. During both processes, several structural changes occur which are linked to processing conditions, including cooking temperature, screw speed, formulation, and initial moisture content. However, a clear relationship between processing variables and the structure of pellets and expanded products has not yet been identified. Accordingly, this work aimed to study the effect of extrusion temperature (110, 135, and 150 °C) and moisture content (27, 29, and 31%) in rice-flour pellets and their microwave expansion, through a microstructural approach using micro-CT. The results showed that the lowest moisture content (27%) and the highest extrusion temperature (150 °C) led to the highest pellet volume and the highest wall thickness, which in turn led to the highest expansion after microwave heating (50 s, 800 W). Interestingly, no significant differences were observed when analyzing the ratio between the volume of the expanded products and the volume of the pellet (~2.4) when using the different processing conditions.

Innovative technology of the process of disinfection and inactivation of antinutrients in compound feeds using liquid components

Научный и практический интересы представляют процессы обеззараживания и инактивации антипитательных веществ в комбикормах. Известны разные технологии обеззараживания (например, нагрев, давление, растворы антимикробных препаратов и другие новые технологии) для повышения эффективности снижения риска заболеваний не только животных и птиц, но и людей. Процессы обеззараживания и инактивации антипитательных веществ может применяться к широкому набору пищевых продуктов и к сырью комбикормовой промышленности. Однако необходимо провести дальнейшие исследования, чтобы понять кинетику инактивации антипитательных веществ в комбикормах для достижения приемлемой технологии обеззараживания. Исследовано влияние гидротермической обработки на поверхностную и глубинную микрофлору зернового сырья. С увеличением времени обработки пшеница и ячмень, искусственно зараженные, а также зараженные естественным способом, были обеззаражены предлагаемым способом на 100 %. Получены химико-технологические характеристики кондиционированного зерна, результаты которых представлены для процессов пропаривания и охлаждения. Установлено, что с увеличением температуры влажность пропаренных и увлажненных зерен пшеницы возрастает с 15,2 до 21,7 %, для зерен ячменя - с 15,3 до 12,8 %. При этом исходная влажность пшеницы составила 10,8 %, а ячменя - 11,2 %. Определено, что при увеличении продолжительности пропаривания и увлажнения зерен пшеницы давление уменьшается с 0,15 до 0,19 МПа и уменьшается расход пара с 85 до 60 кг/т. Анализ физико-механических свойств для пшеницы и ячменя показал, что объемная масса исследуемых образцов возросла. Угол естественного откоса составил для пшеницы 45-48, для ячменя 43-50. Трехстадийную технологию гидротермической обработки комбикормов рекомендуется использовать в трехсекционном реакторе-кондиционере, в котором продукт равномерно кондиционируется с инактивацией антипитательных веществ, обеззараживается и частично желатинизируется. The processes of anti-nutrients disinfection and inactivation in compound feeds are of scientific and practical interest. Various disinfection technologies are known (for example, heating, pressure, solutions of antimicrobial preparations and other new technologies) to increase the effectiveness of diseases risk reducing not only for animals and birds, but for humans as well. The processes of anti-nutrients desinfection and inactivation can be applied to a wide variety of food products and feedstock raw materials. However, further research is necessary to understand the kinetics of anti-nutrients inactivation in compound feeds to achieve an acceptable disinfection technology. The influence of hydrothermal treatment on the surface and deep microflora of grain raw materials was investigated in the work. With an increase in the processing time, both artificially infected and naturally infected wheat and barley were 100 % disinfected with the method proposed. Chemical- and technological characteristics of conditioned grain were received. Their results are presented for the steaming and cooling processes. It was found out that with an increase in temperature, the humidity of steamed and moistened wheat grains increases from 15.2 to 21.7 %, and of barley grains from 15.3 to 12.8 %. At the same time, the initial moisture content of wheat was 10.8 %, and of barley - 11.2 %. It was determined that with an increase in the duration of steaming and moistening of wheat grains, the pressure decreases from 0.15 to 0.19 MPa, and the steam consumption decreases from 85 to 60 kg/t. Analysis of wheat and barley physical- and mechanical properties revealed that the bulk density of the samples studied increased. The repose angle was 45-48 for wheat and 43-50 for barley. It is recommended to use a three-stage technology of compound feed hydrothermal treatment in a three-section reactor-conditioner. The product is uniformly conditioned with anti-nutrients inactivation, disinfected and partially gelatinized in it.

Performance evaluation of a flatbed maize dryer with a biomass heat source

The technical performance of a 3-tonne capacity flatbed grain dryer was assessed based on its drying rate and drying efficiency. In addition, the quality of maize grains dried in the drying system was investigated through stress-crack analysis and germination test. Maize grains at an initial moisture content of 18.4% ± 0.1% (wb) were dried to a safe moisture content of 13.3% ± 0.2% (wb) in 5 hours, resulting in a drying rate of 1.02%/h at a drying efficiency of 67.35%. The average temperature observed in the plenum (55.8°C±1.5°C) was about twice higher than the ambient temperature during the drying period. The use of the flatbed dryer did not have any adverse effect on the viability of grains dried with a stress-crack index of 75 and percentage germination of 90%. This study demonstrated the viability of using the flatbed biomass-assisted dryer for drying maize and can reduce post-harvest losses of maize at the smallholder level. Int. J. Agril. Res. Innov. Tech. 11(2): 37-41, Dec 2021

Measurements and Analysis of the Physical Properties of Cereal Seeds Depending on Their Moisture Content to Improve the Accuracy of DEM Simulation

This article presents the results of research on the influence of moisture on changes in the physical properties, i.e., the length, width, thickness, and weight, of dressed and untreated cereal seeds in order to improve the simulation process based on the discrete element method (DEM). The research was conducted on the seeds of three winter cereals, i.e., triticale, rye, and barley. The seeds with an initial moisture content of about 7% were moistened to five levels, ranging from 9.5% to 17.5%, at an increment of 2%. The statistical analysis showed that moisture significantly influenced the physical properties of the seeds, i.e., their length, width, thickness, and weight. As the moisture content of the seeds increased, there were greater differences in their weight. The average increase in the thousand kernel weight resulting from the increase in their moisture content ranged from 4 to 6 mg. The change in the seed moisture content from 9.5% to 17.5% significantly increased the volume of rye seeds from 3.10% to 14.99%, the volume of triticale seeds from 1.00% to 13.40%, and the volume of barley seeds from 1.00% to 15.33%. These data can be used as a parameter to improve the DEM simulation process.

Experimental Study on the Effect of Freezing and Thawing on the Shear Strength of the Frozen Soil in Qinghai-Tibet Railway Embankment

The direct shear tests of different dry density and moisture content samples at different temperatures of the frozen soil in the Qinghai-Tibet Railway embankment between Tanggula South and Anduo section were carried out to analyze the influence rules of each experimental factor on the mechanical properties of frozen soil during the freeze-thaw process. The results show the following. (1) When the frozen soil temperature is below 0°C and continues to drop during the freezing and thawing process, each sample shows the law of a significant increase in cohesion and a slight decrease in the internal friction angle. In the meantime, the cohesion obtained during the thawing process of the sample at the same temperature point is higher than that obtained during the freezing process. In contrast, the internal friction angles exhibit an opposite law, where the internal friction angle during the melting process is lower than the internal friction angle during the freezing process. After freezing-thawing action, it deserves to be mentioned that the cohesion increases slightly while the internal friction angles present a slight decrease trend compared to the initial state. (2) With the decrease in temperature and the gradual increase in cohesion, the temperature curve can be divided into a fast-growing section from 0 to −2°C, a slow-growing section from −2 to −8°C, and a second fast-growing section from −8 to −10°C owing to the combined effect of the pressure-thawing action and ice-water phase change. In addition, the rate of decrease in the internal friction angle also shows a similar pattern. (3) The cohesion and the internal friction angle of samples both tend to increase first and then decrease with the rise of the initial moisture content, and the critical initial moisture content is near the optimal moisture content of 15%. (4) Both the cohesion and the internal friction angle of the samples increase with dry density growth. The growth rate of cohesion will gradually increase as the temperature decreases. Moreover, the growth rate of cohesion of low dry density samples is more susceptible to temperature, while the internal friction angle growth rate is not affected by temperature.

The application of vapour equilibrium technique to control suction to study the shrinkage and water retention of compacted Claystone-Bentonite mixtures

Understanding soil shrinkage and retaining water is essential for learning more about the possibility of cracking of liner. Moreover, the factors that influence it are also important to know to improve the material tested as hazardous waste liners. The vapour equilibrium technique is widely used to control suction of compacted soils experiencing drying-wetting phenomena. It is considered to be inexpensive, simple, and has the ability to adequately control the suction applied to soil samples. This paper, therefore, describes its application in studying the shrinkage and water retention in compacted claystone-bentonite mixtures. This involved using five saturated salt solutions including potassium sulphate (K2SO4), potassium chloride (KCl), sodium chloride (NaCl), potassium carbonate (K2CO3), and magnesium chloride (MgCl2.6H2O). The sample was allowed to be in equilibrium with the relative humidity salt solution and a calliper was used to measure the dimensions every day up to when this was achieved. The results showed the bentonite in the mixture affects the amount of shrinkage and water retention while the sample’s initial moisture content was also found to be very influential on the magnitude of the primary and residual shrinkage. Moreover, the sample’s ability to hold water was almost the same without differentiating the initial water content at a total suction of more than 41084.91 kPa.

Effect of Lightweight Aggregate Impregnation on Selected Concrete Properties

The impregnation of lightweight aggregate (LWA) is an alternative method to its pre-moistening, which is used to limit the loss of fresh concrete workability due to the aggregate’s ability to absorb a great amount of mixing water. The aim of this study was to access the effectiveness, by pre-coating LWAs with cement paste, in modifying the properties of concrete composites. Two types of lightweight aggregates (Lytag and Leca) characterized with a relatively open-structure shell were selected. The other changeable parameters taken into consideration in this research were: LWA size, initial moisture of aggregate before the impregnation process and type of cement paste applied as an impregnant. Sixteen concretes prepared with pre-moistened and pre-coated lightweight aggregates were subject to a density test in different moisture conditions, a water absorption test and a compressive strength test. On the one hand, the pre-coating of LWAs with cement paste resulted in a relatively slight increase in concrete density (by up to 19%) compared to the pre-moistening of LWAs. On the other hand, it caused a very significant reduction (by up to 52%) in the composite’s water absorption and an incomparably greater growth (by up to 107%) in compressive strength. The most crucial factors determining the effectiveness of impregnation of LWAs with cement pastes in improvement of composite properties were the aggregate type and its size. The composition of impregnating slurry and the initial moisture content of LWA before pre-coating also mattered.

Bioremediation of artificially crude oil polluted soil of veritas University Abuja using poultry manure

The removal of hydrocarbon compounds from the environment has always been a difficult undertaking for people all over the world. As a result, remedial efforts are required to safeguard the environment as well as to restore agriculture. This study looked at how poultry manure (dung) could help in the bioremediation of Veritas University's intentionally crude oil polluted soil. The physical properties of the soil and total petroleum hydrocarbon content of the crude oil polluted soil were determined, followed by the isolation and identification of microorganisms present in the soil and poultry manure before and after pollution with crude oil. These analyses were done according to standard operating procedures. Within a six-month timeframe, the natural attenuation and poultry manure amendment option for remediating the crude oil-polluted soil were monitored and the residual hydrocarbon content of the polluted soil after remediation evaluated. There was an overall decrease in pH level during the experimental units containing 4 g amendment, 2 g amendment and the untreated polluted soil in the order 8.4 to 7.1, 8.4 to 7.2 and 8.1 to 6.7, respectively. Temperature was within 27oC and 31oC, the treated soil that contained 4 g dung had an initial moisture content of 58%, and 35% after remediation. The hydrocarbon utilizing bacteria isolated were Pseudomonas species, Staphylococcus species, and Bacillus species, while the hydrocarbon utilizing fungi isolated were Aspergillus niger, Fusarium solani and Candida albicans. There was more significant microbial increase in the sample containing 4 g poultry manure treatment than 2 g poultry manure treatment and natural attenuation. Total hydrocarbon quantity significantly decreased after six months with the complete removal of C4, C7, C19 and C37 from the treated sample containing 4 g poultry manure. This indicated that the negative effects of crude oil on the environment can be mitigated by adding poultry manure.

Thermal Analysis of Tilapia Fish Drying by Hybrid Solar Thermal Drying System

The present work presents a hybrid solar thermal drying of Tilapia fish to improve the product quality and satisfy the importers. The developed hybrid dryer utilized direct solar drying, a solar air heater and a thermal backup unit which sustains the drying process during the night, cloudy and rainy weather conditions. Besides, a new feature of the developed dryer utilizes the flue gas exhausted from the thermal unit to enhance the updraft in the drying chamber by re-injection of the flue gases in the chimney. The initial moisture content of the Tilapia fish used in the investigation was 246.6% on a dry basis, equivalent to 74% on a wet basis. The investigations were repeated three times on different days. Experimental results showed that the moisture content was reduced to an average final of 17.0% db (5.0% wb) within 17.5 hours, while in the open sun drying, it required around 48-72 hours. Hybrid solar drying required around 72% shorter time than open sun drying. The average overall drying efficiency of the developed system for drying Tilapia fish was 13.0%. The Re-injection technique used in the present hybrid solar-thermal system has excluded the need for an electric source for air extraction from the drying chamber, which is highly desired in the rural and fishery regions.