Study on the Influence of Moisture Content and Drying-Wetting Cycles on the Shear Strength Index of Silt in the West Bank of Qinghai Lake

In this paper, the expressway engineering case along the west bank of Qinghai Lake is taken as the research background, and the typical “aquatic grassland” silt on the west bank of Qinghai Lake is taken as the research object. Through the geotechnical test, wet-dry cycle test, and direct shear test, the influence of moisture content and wet-dry cycle on the shear strength of silt and its indexes are studied. The results show that the shear strength index c and φ of unmodified silt first increase and then decline with the increase of water content, and the optimal moisture content of the shear strength is about 30%. The values of c, φ, and shear strength of remolded silt decrease with the increase of wetting and drying cycles. When the cycles exceed 5 times, the moisture content does not have much effect on the shearing strength.

Compressive strength of cement stabilizations containing recycled and waste materials

This study analyses the possibilities of using up to 30% of reclaimed asphalt pavement as a substitute material for natural aggregate, along with fly ash replacing 20% or 40% of Portland cement in cement stabilizations with 4% and 6% of binder. The Proctor test was used to determine maximum dry density and optimal moisture content of cement-based stabilizations. The compressive strength was tested after 7, 28, and 90 days. Parameters influencing 28-day compressive strength were evaluated by full factorial design and by classification in strength classes. The results obtained justify the utilisation of waste and recycled materials in pavement structures.

THE ACTION OF SOME CYTOKININ-TYPE COMPOUNDS ON THE ANTIOXIDANT PROTECTION CAPACITY OF PLANTS IN CONDITIONS OF UNFAVORABLE VARIATION OF HUMIDITY AND REPEATED WATER STRESS

The effect of cytokinin-type compound on the capacity of the enzymatic and non-enzymatic system of antioxidant protection by plants in conditions of humidity fluctuation and repeated drought were studied. As subjects served the plants Glycine max (Merr) L.cultivar Nadejda, grown in the Mitcherlih vegetation pots with volume of 40 kg soil and exposed to the drought stress at the phases first trifoliate leaf and flowering – pods formation. The antioxidant protection capacity of soybeans pre-treated with cytokinin, thiourea and with the composition Polyel + phytohormones (AIA, Gb, CK)is ensured both by the intensification of the activity of antioxidant enzymes and by the increase of content of non-enzymatic substances with low molecular weight.After restoring the optimal moisture content, the plants pre-treated with thiourea and Polyel + F more fully restore their functional processes.

Study of the kinetic regularities of the grain extrusion process in the production of highly digestible feed with protected protein for cattle

The problem of developing of highly digestible compound feeds with protected protein for cattle is due to the specifics of the gastric tract of cows and the peculiarities of protein assimilation. Due to the importance of preliminary moisture-heat treatment of grain for the subsequent course of the extrusion process, it was carried out by steam at a pressure of 0.6 МРа before moistening the feed to a humidity of 17–20% and heating to a temperature of 70–80° C. It is established that heat treatment has a significant effect on the carbohydrate complex of grain: heating it at high temperatures causes the destruction of starch, accompanied by the formation of easily soluble carbohydrates, which has a positive effect on the digestibility of feed. The kinetic regularities of the processes of moisture-heat treatment, grinding and extrusion of grain in the production of highly digestible feed with protected protein for cattle were studied. The degree of dextrinization and the digestibility of starch increased with the heating temperature of corn and its mixtures with wheat up to 100–110° C, when the performance of the extruder was 300–320 kg/h, the digestibility of starch extruded corn and grain mixture is increased to 85 and 68 mg of glucose per 1 g of the product (hereinafter mg/g), respectively. For wheat, this indicator is lower and, accordingly, is 50 mg/g. When heated during the extrusion of corn to a temperature of up to 120–140° C, the digestibility of starch was 100–110 mg/g, and for the grain mixture – 80–83 mg/g. At this temperature, the digestibility of the starch of extruded wheat corresponded to 60–65 mg/g. The optimal moisture content of feed in the process of extrusion for the purpose of forming pellets is 18%. Studies of the extrusion effect on the carbohydrate complex of processed feed have shown that the destruction of starch in the extruded product increases. Thus, the content of soluble carbohydrates increases by 27–32%, and the digestibility of starch increases twice in extruded feed compared to unprocessed.

Influence of Laboratory Compaction Method on Compaction and Strength Characteristics of Unbound and Cement-Bound Mixtures

During road construction, granular materials for the unbound base course (UBC) and cement-bound base course (CBC) are mostly compacted by vibratory rollers. A widespread laboratory test for determining the optimal moisture content (OMC) and maximum dry density (MDD) of the mixture for installation in UBC and CBC is the Proctor test. Considering that the Proctor test does not produce any vibrations during compaction, this paper compares the Proctor test and the vibrating hammer test. The examination was conducted on UBC and CBC with varying cement content and aggregate types. All mixtures were compacted by both methods with the aim of determining the compaction and strength characteristics. The results indicated the high comparability of the two test methods for mixtures with natural aggregate in terms of MDD, OMC, density and strength characteristics (California bearing ratio (CBR) for UBC and 28-day compressive strength for CBC). For mixtures with higher cement content, the OMC difference depending on the laboratory compaction method used can be significant, so the laboratory compaction method should be chosen carefully, particularly for moisture-susceptible materials. This paper also reveals that by increasing the proportion of rubber in the mixture, the compaction and strength characteristics differ significantly due to the compaction method. Therefore, when using alternative and insufficiently researched materials, the compaction method should also be chosen carefully.

Studi Pengaruh Abu Batu Bata terhadap SifatFisik dan Mekanik Lempung Terstabilisasi Kapur dari Kecamatan Tenayan Raya

Tenayan Raya Subdistrict is an area that has a thickness of soft clay layer. Some cases of building failure were cracks and tilts due to high shrinkage of soil. Nearby is also a brick home industry center, where ashes are produced from bricks burning. Soil Improvement of Tenayan-Raya's Clay and utilization of brick ash will be carried out in this research. This study aims to stabilize the soil with lime and utilize the brick ash to improve shear strength and bearing capacity of the soil. The study was conducted in the laboratory by making several combinations of content clay, lime, and Brick Ash (BA), for the soil mixture which will be added with 10% ash brick. The effect of curing and soaked will also be seen for its rising on soil properties of Unconfined Compression Strength, and CBR laboratories. The influence of water will also be reviewed on the dry side, optimal moisture content, and wet side. The test results show that the Soil has Low Plasticity soil type category CL-ML symbols, according to the Unified classification. Increasing of strength due to stabilization with lime is obtained in conditions of water in optimal moisture content, where the addition of lime is 10% and 10% brick ash, was produced to increase the maximum value of Unconfined Compression Strength and CBR laboratory value. Curing setup time and saturation (soaked) also had affect the value of Unconfined Compressive Strength and CBR laboratory test. At longer time for curing, shear strength will rise proved by the value of UCS Test andbearing capacity value also increase that can be seen of the laboratory CBR test. Curing will make the shrinkage of clay reduced, this can be proven from differences value of Unconfined Compressive strength test between samples with and without soaked, are relatively small.

Study on Mechanical Properties of the Expansive Soil Treated with Iron Tailings Sand

Aiming at researching shear strength parameters of expansive soil modified by industrial waste iron tailings sand, the enhancement of expansive soil is explored from macroscopic and microscopic aspects. After characterization and testing by various means, the results show that expansive soil modified by iron tailings sand will increase the maximum dry density of the improved soil and reduce its optimal moisture content, which is beneficial in tuning the moisture content at the construction site. In addition, iron tailings sand can improve the shear strength of expansive soils. The influence of iron tailings sand on cohesion increases first, then decreases, and reaches the peak value at 30%, while the effect on internal friction angle exhibits a continuously increasing trend. Furthermore, according to mercury intrusion tests and microangle analysis, the addition of iron tailings sand can reduce the tiny pores and enhance the occlusal force of the soil. Simultaneously, it increases the number of large pores, maximizing the macroscopic strengthening of iron tailings sand towards the expansive soil.

Multiscale Analysis of the Strength Deterioration of Loess under the Action of Drying and Wetting Cycles

To study the strength degradation mechanism of compacted loess during dry-wet cycles, 0–5 dry-wet cycles tests and many triaxial compression tests were carried out on loess with an optimal moisture content. During the dry-wet cycles, the loess samples were analyzed by nuclear magnetic resonance and scanning electron microscopy. Studies have shown that at the macro level, with increasing numbers of wet and dry cycles and increasing cycle amplitude, the cohesive force and internal friction angle of the loess decrease, and the shear strength of the loess deteriorates significantly. At the micro level, with the number of wet and dry cycles increasing, the connection between particles changes from surface-to-surface contacts to point-to-point or point-to-surface contacts. The edges and corners of the particles decrease, the roundness increases, the large pores gradually decrease, the small pores gradually increase, and the fractal dimension gradually increases. In terms of microscopic view, the NMR test shows that with increasing numbers of dry-wet cycles, the T2 peak curve increases, the curve width increases slightly, the peak area gradually increases, and the porosity increases. From the macroscopic, mesoscopic, and microscopic multiscale analysis, the structure of loess is degraded under the action of dry and wet cycles; the strength of the loess is degraded significantly after 0 to 3 cycles and then gradually stabilizes. These research results can provide a certain reference value for the management of loess collapse geological disasters in semiarid climates.

Effect of Frying Conditions on Self-Heating Fried Spanish Mackerel Quality Attributes and Flavor Characteristics

In this study, we investigated the effects of different frying conditions on the quality characteristics of fried Spanish mackerel (Scaberulous niphonius) to address the food quality degradation of self-heating fish products after frying, sterilization, and reheating. Furthermore, the effect of different moisture contents (65%, 60%, 55%, and 50%) of fried Spanish mackerel on texture, color, and microstructure after sterilization and self-heating were examined. The flavor fingerprints of different frying temperatures (140 °C, 160 °C, 180 °C, and 200 °C) coupled with the optimal moisture content were identified; furthermore, volatile organic compounds (VOCs) were studied using headspace-gas chromatography-ion mobility spectrometry (HS-GC-IMS) with principal component analysis (PCA). The results indicated that the shear force value significantly increased, while the hardness and chewiness significantly decreased simultaneously with decreasing moisture content. Samples containing 65% moisture content showed the highest L*, a*, and W values, while their b* value was the lowest, and the most clearly visible fibrous veins with tiny cracks could be observed in them. Samples fried at 160 °C and 65% moisture content exhibited the richest VOCs, with a greasy or fried aroma. Based on the PCA, there were significant differences in the sample VOCs under different frying conditions. In summary, among all treatments, frying at 160 °C with 65% moisture content resulted in the highest food quality of fish filets. The results of this study could provide a theoretical basis for improving the food quality of self-heated fish products.

Siderurgical Aggregate Cement-Treated Bases and Concrete Using Foundry Sand

Cement-treated bases are soils, gravels or manufactured aggregates mixed with certain quantities of cement and water in order to improve the characteristics of a base or sub-base layer. Due to the exploitation of natural aggregates, it is a matter of importance to avoid shortage of natural resources, which is why the use of recycled aggregates is a practical solution. In this paper we studied the feasibility of the use of untreated electric arc furnace slags and foundry sand in the development of cement-treated bases and slag aggregate concrete with a lower quantity of cement. We analyzed the physical, mechanical and durability characteristics of the aggregates, followed by the design of mixes to fabricate test specimens. With cement-treated bases, results showed an optimal moisture content of 5% and a dry density of 2.47 g/cm3. Cement-treated bases made with untreated slag aggregate, foundry sand and 4% of cement content showed an unconfined compression strength at seven days of 3.73 MPa. For siderurgical aggregate concrete mixes, compressive strength, modulus of elasticity and flexural strength tests were made. The results showed that the mixes had good mechanical properties but durability properties could be an issue.