Moisture Range Research Articles

The development of rotational molding of waste bamboo powder with LLDPE plastic powder

The objective of this study was to assess the effect of bamboo powder addition and the treatment of its surface on the properties and structure of rotationally molded (rotomolded) polypropylene. In this study we can transform plastic and bamboo powder into a product by putting the raw materials into hollow mold and then cover the mold. The mold is rotated along two axes by burning with high temperature to make liquid plastic flows evenly along the inner surface of the mold with gravity. The results of this research had shown that, by using LLDPE plastic 4 kg, bamboo waste powder 1 kg size of 0.15: 0.30: 0.85 mm tested with humidity 10:15:20% mixed and then molded, it was found that the moisture of waste bamboo powder had a direct effect on molding. If the moisture in the bamboo powder is more than 20%, the work will not be molded. It shown look like a lump. The moisture content less than 15% can be molded as a product. In terms of the size used in this test 0.15: 0.30: 0.85 can be molded well in the range of moisture, not more than 15%.

Water Sorption by Carbon Fibers

The degree of crystallinity of carbon fibers (CFs) of different manufacturers has been determined by means of the Raman scattering method. A gradient “core–shell” model for the CF structure has been suggested. The element composition of CFs has been determined by means of the X-ray electron probe analysis. It has been established that the CF includes oxygen-containing groups, the concentration of which varies from 2 to 4 wt %. A fibrillar structure of the CF shell has been identified via the methods of atomic force probe microscopy and transmission electron microscopy. Longitudinal and transverse sizes of fibrils have been determined. Using the method of low-temperature nitrogen adsorption, the specific surface area, porosity, and pore sizes of CFs have been determined. Isotherms of water vapor sorption by CF within the moisture range from 10 to 95 wt % have been obtained. It has been demonstrated that, for all the studied samples, the sorption isotherms can be approximated using the Dubinin–Radushkevich equation. The sorption capacity of water vapor by CFs has appeared to significantly exceed that of nitrogen, which was associated with the presence of oxygen-containing functional groups.

Desorption isotherms of flaxseeds (Linum usitatissimum L.) and thermodynamic parameters of the process

Sorption isotherms of flaxseeds were determined by static gravimetric method at temperatures 40; 60; and 80 oC, over a relative moisture range of 10-95%. Six mathematical models were applied to analyze the experimental data. The modified GAB model showed the best fitting to the experimental data. The isosteric heat and differential entropy were determined by applying Clausius-Clapeyron and Gibbs-Helmholtz equations, respectively. The isosteric heat and the entropy of desorption isotherm presented similar behavior, with a sharp change in an equilibrium moisture content of 10%. The enthalpy-entropy compensation theory was applied to the isotherms, indicating that they are enthalpy-controlled.

Uticaj sadržaja vlage na termičke parametre zrna Konjskog oka relevantnog za proces prerade

The specific heat, thermal conductivity and thermal diffusivity of the Horse-Eye bean (Mucuna sloanei) were determined as a function of moisture content using the method reported by A.O.A.C (2000). The sample varieties used were the Big Sized and the Small Sized Horse-Eye bean. The specific heat and the thermal conductivity were measured using a Bomb Calorimeter. The thermal diffusivity was calculated from the measured specific heat, thermal conductivity and bulk density of the samples. Within the moisture range of 10.5% to 16.87% (b.b), the specific heat, thermal conductivity and thermal diffusivity varied with the moisture content. Results showed that the specific heat, thermal conductivity and thermal diffusivity of the Horse-Eye bean seeds ranged from 116.76 to 203.29 kJ/kgK; 21.07 to 32.23 W/moC; and 3.12 x 10-7 to 9.19 x 10-7 m 2 /s, for the Big Sized varieties, and 112.06 to 194.61 kJ/kgK; 19.85 to 24.08 W/moC; and 3.05 x 10-7 to 6.71 x 10-7 m 2 /s, for the Small Sized varieties as the moisture content increases from 10.5% to 16.87%. Regression analysis were also carried out on the thermal properties of the Horse-Eye bean varieties and moisture content, and there was positive relationship between the parameters. There were significant effects of moisture content (p < 0.05) on all the parameters conducted. The findings and the data generated will create an impact in the food processing industries for Horse-Eye bean.

Controls of Temporal Variations on Soil Respiration in a Tropical Lowland Rainforest in Hainan Island, China

Soil respiration represents the largest carbon (C) flux from terrestrial ecosystems to the atmosphere. We created a study site in tropical lowland rainforest and used static chamber method to measure the temporal variations of soil respiration and their relationship with environmental factors at monthly time scale. The temporal variations of soil respiration showed a seasonal pattern related to soil temperature (p < .01) and soil moisture (p < .05). We tested different regression models to explore the relationship between soil respiration and environmental factors. Soil respiration had a better fit with soil temperature than with soil moisture in single-factor models. At different temperatures, the Q10 values from different models changed in rather different ways. We found that the mixed quadratic model composite of soil temperature and moisture had the best-fitting effect (R2 = .74) on soil respiration and could better explain the seasonal variation. In a certain soil moisture range close to 15%, soil respiration increased with soil temperature. However, soil respiration became restricted when the moisture was greatly higher or lower than this value. Furthermore, at low soil temperatures (lower than 16°C), higher soil moisture could decrease soil respiration rapidly. Thus, soil respiration in a tropical lowland rainforest is co-controlled by soil temperature and moisture. This study expands our observations of soil respiration in tropical forests and how it responds to environmental factors, which is important for reducing errors in evaluation and scaling up of soil carbon flux in climate change studies.

Utilization of Jamun seed powder in composite cake formulation

The study is concerned with the evaluation of the nutritional and functional properties of Jamun seed powder (JSP) extracted from fresh Jamun and to develop cakes by incorporating JSP with wheat flour (WF). The chemical analysis showed that JSP had 6.30% moisture, 6.24% protein, 2.19% ash, 1.18% fat, 84.09% carbohydrate and 371.94 Kcal energy/100 g of powder whereas WF contained 12.90% moisture, 11.00% protein, 1.35% ash, 1.50% fat, 73.01% total carbohydrate and 349.54 Kcal energy/100 g of powder. Four cake samples were prepared by using different proportion combination of WF and JSP such as A (100% WF), B (90% WF and 10% JSP), C (80% WF and 20% JSP) and D (70% WF and 30% JSP). The nutritional components of four cake samples gave the range of moisture 16.92-25.56%, protein 6.34-8.56%, ash 1.50-2.60%, fat 16.01-22.42% and total carbohydrate 41.96-58.13%. Weight (g) of processed cakes were increased whereas other physical attributes such as volume, height, specific volume were decreased due to supplementation of JSP. The increased level of JSP powder substitution changed the crust color of cakes from light brown to blackish and also changed the crumb color from brownish to reddish. Sensory evaluation indicated that the sample B (10% JSP and 90% WF) was the most acceptable by the panelists than those of other cakes. Above all, the study gave an indication that Jamun seed powder can be used as a good replacement of wheat flour in production of cakes which can help to get higher energy, mineral and carbohydrate.&#x0D; &#x0D; J Bangladesh Agril Univ 17(4): 599–605, 2019

DEVELOPMENT EXPERIENCE AND WAYS OF IMPROVEMENT OF IRRIGATION MANAGEMENT SYSTEMS

The paper provides an overview of models and software used in decision support systems in irrigation. The models of biomass accumulation or evapotranspiration are the base of decision support systems in irrigation. The overview of the most famous systems is given, as well as an innovative irrigation control system "Irrigation online" is presented. &#x0D; The objective of the work is to share the experience of development and implementation of irrigation management systems and outline the ways of their improvement.&#x0D; The "Irrigation online" system consists of hardware and software components. The part of the system's hardware is located in the field consisting of iMetos or Davis weather stations, as well as of own-developed equipment. The software part, intended for storing, processing and providing recommendations, is hosted and run on a server. It sends the recommendations about start watering and necessary irrigation rates to a user’s computer or mobile device.&#x0D; The system is based on modelling of moisture transfer, automated measurements of soil moisture and meteorological indicators in the field and weather data from automated forecast web-sites. Water retention curve of soil and the dependence of the moisture transfer coefficient on the head, which are the input parameters of the model, are given for every layer according to the van Genuchten-Mualem Model.&#x0D; The application of the system took place in 2019 in SE EF“Askaniiske” Kherson region and LLC “APC “Mais” in Cherkasy region. The system "Irrigation Online" provided the recommendations on watering winter rape, wheat, corn, soybeans, alfalfa and potatoes. &#x0D; The system provided the recommendations on watering winter rape, wheat, corn, soybeans, alfalfa and potatoes. It was specified that the use of the system "Irrigation Online" enables to schedule irrigation regimes, the implementation of which requires watering with less (by 15-25%) in comparison with the current irrigation rates, due to which more favourable conditions for the maximum realization of crop varieties and hybrids potential are created. It is accompanied by enhancing the environmental safety of irrigation as a result of minimization of irrigation water losses for infiltration.&#x0D; Irrigation control system "Irrigation Online" uses a range of soil moisture suction pressure rather than a soil moisture range as an optimum moisture supply range for plants. For setting up irrigation terms and rates, the value of suction pressure, which corresponds to the part of water field capacity when it is determined by water retention curve of soil, is taken. The pre-irrigation threshold of suction pressure is the value, which at non-irrigation for some short period will not cause water stress for plants &#x0D; Monitoring of meteorological parameters and soil moisture level in the "Irrigation Online" system allows daily adjusting irrigation terms and rates for next 5 day period and significantly improves the accuracy of their forecasting.

Effect of Processing on the Nutritional Composition of Moringa olifera Leaves and Seeds

Background/Objective: Processing improves the nutritional quality of food and may/not lead to nutrient losses. Processing is done to eliminate inactive microorganisms/ antinutrients and extend the shelf life of food. Moringa oleifera plant is an important tree in some part of Nigeria having been successfully used as food, medicinal and for industrial purpose. This study was designed to determine the effect of processing on the nutritional profile of Moringa olifrera leaves and seeds.&#x0D; Materials and Methods: The leaves and seeds were harvested from the forest. The leaves were washed, drained and divided into three portions. The first portion was processed raw, the sun and shade dried samples were the second and third portion. The seeds were cracked and divided into six portions. The first portion was processed raw and the other five portions were fermented for 24, 48, 72, 96 and 120 h respectively. The samples were analyzed for proximate, vitamin, mineral, and anti-nutrients contents using the standard method.&#x0D; Results: The proximate composition of the seeds showed that the samples had a range of moisture, 16.63-17.75%, protein 13.92-38.45%, fat 14.93-19.00%, fibre 3.94-7.10%, ash 1.96-6.22% and carbohydrate 9.08-36.61%/100 g respectively. The ranges for the mineral contents of the seeds were iron 2.10-33.35 mg, zinc 1.19-1.35 mg/100 g, and iodine 12.33-126.61 mg. Also, the ascorbic acid content of the seeds ranged from 3.57- 24.55 mg. The anti-nutrient contents of the seeds were 0.03 – 1.35/100 g saponin, 0.21 – 6.25 mg/100 g of oxalate, 0.11 – 0.28 mg tannins and 5.69 – 16.81 mg/100 g of phytate. The proximate composition of the vegetables ranged from 8.99 – 75.33% moisture, 6.01 – 17.78% protein, 0.64 – 3.89% fat, 3.14 – 11.96% fibre, 2.46 – 15.22% ash and 12.01 – 48.52% carbohydrate. The ranges for mineral contents of the vegetables were iron 0.04 – 0.23 mg, zinc 0.03 – 0.10 mg and iodine 13.66 – 46.61 mg. The vitamin levels of the vegetables were ascorbic acid 56.43 – 167.66 mg/100 g. The level of the anti-nutrients in the vegetables ranged from 0.04 – 1.26 mg/100 g saponin, 0.31 – 8.44 mg/100 g oxalate, 0.05 – 0.20 mg/100 g tannins while phytate varied from 3.31 – 13.20 mg/100 g.&#x0D; Conclusion: Processing of both leaves and seeds of Moringa olifera increased their nutrient density and reduced the concentration of anti-nutrients. The consumption of Moringa olifera should be popularized to diversify diet and extend their food use.

Prediction of effective moisture diffusivity in plant tissue food materials over extended moisture range

Effective moisture diffusivity provides an easy and expeditious route to understanding many moisture transport processes involving food materials. Instead of making the moisture diffusivity a parameter obtained from curve-fitting a given experimental data that severely restricts its predictive value for the different sets of conditions, a simple but mechanistic approach is provided that for its prediction uses very little empirical information. This approach is based on treating the food as porous media and using parameters such as relative permeability, porosity, tortuosity, and constrictivity. The parameters are predicted using well-known relationships. The model is a combination of liquid and vapor diffusion-weighted by the respective volumes present in the porous medium that provides effective moisture diffusivity. Our model is compared to a mechanistic model that is backboned by Kelvin’s capillary pressure equation and experimental isotherms data. In addition, the prediction is thoroughly validated against available experimental data and the general understanding of liquid/vapor transport in porous media literature. The more mechanistic approach enables prediction over a broader range of moisture content and a greater range of food materials with acceptable RMSE compared to other literature models.

On sorption hysteresis in wood: Separating hysteresis in cell wall water and capillary water in the full moisture range.

Moisture influences most physical wood properties and plays an important role in degradation processes. Like most other porous materials, wood exhibits sorption hysteresis. That is, the moisture content is higher if equilibrium is reached by desorption than if it is reached by absorption under the same ambient climate conditions. The mechanism of moisture uptake by wood are different in the hygroscopic and over-hygroscopic moisture ranges and due to methodical issues, most studies of sorption hysteresis have been performed in the hygroscopic range. In the present study, total sorption hysteresis was separated into hysteresis in cell wall water and capillary water respectively in the whole moisture range by a novel combination of experimental techniques. Wood specimens were conditioned to several high moisture contents using a new system based on the pressure plate technique, and the distinction between cell wall water and capillary water was done with differential scanning calorimetry. The results showed that sorption hysteresis in wood cell walls exists in the whole moisture range. The cell walls were not saturated with water until the whole wood specimen was saturated which contradicts the long-held dogma that cell walls are saturated before significant amounts of capillary water are present in wood.

Water retention in different types of protective gel compositions for plant rhizosphere

The research investigates thermodynamic characteristics of water-retention capacity in different types of high swelling polymer hydrogels mixed with mineral soil substrates. The use of a combination of methods of equilibrium centrifugation and thermodesorption of soil moisture allowed for the first time to estimate the water-retaining curves and dispersion of gel compositions in the range of absolute values of thermodynamic potentials from 0 to 1 million J/kg. The introduction of hydrogels in concentrations of 0.1-0.3% total weight of the enclosing mineral material leads to a 5-15 fold increase in the total energy of water retention, 3-8 fold increase in water capacity and available moisture range, bringing investigated hydrophysical characteristics of the original sandy substrate at the level of the fertile loamy soils. The new types of acrylic hydrogels with amphiphilic fillers obtained by the author’s technology had a greater water-holding capacity and a better structuring effect in comparison with the “Aquasorb” European trade mark. The incorporation of the electrolyte additives in the form of trace elements and ionic silver into the polymer matrix practically does not change the swelling capacity, allowing adding elicitor and antimicrobial properties to these compositions without compromising the effect of water retention.

Evaluating Soil-Borne Causes of Biomass Variability in Grassland by Remote and Proximal Sensing.

On a grassland field with sandy soils in Northeast Germany (Brandenburg), vegetation indices from multi-spectral UAV-based remote sensing were used to predict grassland biomass productivity. These data were combined with soil pH value and apparent electrical conductivity (ECa) from on-the-go proximal sensing serving as indicators for soil-borne causes of grassland biomass variation. The field internal magnitude of spatial variability and hidden correlations between the variables of investigation were analyzed by means of geostatistics and boundary-line analysis to elucidate the influence of soil pH and ECa on the spatial distribution of biomass. Biomass and pH showed high spatial variability, which necessitates high resolution data acquisition of soil and plant properties. Moreover, boundary-line analysis showed grassland biomass maxima at pH values between 5.3 and 7.2 and ECa values between 3.5 and 17.5 mS m−1. After calibrating ECa to soil moisture, the ECa optimum was translated to a range of optimum soil moisture from 7% to 13%. This matches well with to the plant-available water content of the predominantly sandy soil as derived from its water retention curve. These results can be used in site-specific management decisions to improve grassland biomass productivity in low-yield regions of the field due to soil acidity or texture-related water scarcity.

Study of the relation between soil erodibility and hydrological characteristics

Hydrological characteristics such as soil water retention curve and hydraulic conductivity, for which, however, there are no standardized measurement methods for the entire range of soil moisture, are most important for assessing the erodibility of soil. In the article, based on the energy approach to soil erodibility analysis, a relation was proposed linking the characteristic of soil erodibility, – the specific power spent on the destruction and removal of soil in the places of its natural occurrence, with soil hydrological characteristics. Modeling erosion processes based on the proposed ratio may allow both describing the erosion properties depending on the initial soil moisture and obtaining numerical information on the soil hydrological characteristics using measured values of soil erodibility characteristics at any time during the vegetation period.

Soil Water Infiltration Model for Sprinkler Irrigation Control Strategy: A Case for Tea Plantation in Yangtze River Region

The sprinkler irrigation method is widely applied in tea farms in the Yangtze River region, China, which is the most famous tea production area. Knowledge of the optimal irrigation time for the sprinkler irrigation system is vital for making the soil moisture range consistent with the root boundary to attain higher yield and water use efficiency. In this study, we investigated the characteristics of soil water infiltration and redistribution under the irrigation water applications rates of 4 mm/h, 6 mm/h, and 8 mm/h, and the slope gradients of 0°, 5°, and 15°. A new soil water infiltration model was established based on water application rate and slope gradient. Infiltration experimental results showed that soil water infiltration rate increased with the application rate when the slope gradient remained constant. Meanwhile, it decreased with the increase in slope gradient at a constant water application rate. In the process of water redistribution, the increment of volumetric water content (VWC) increased at a depth of 10 cm as the water application rate increased, which affected the ultimate infiltration depth. When the slope gradient was constant, a lower water application rate extended the irrigation time, but increased the ultimate infiltration depth. At a constant water application rate, the infiltration depth increased with the increase in slope gradient. As the results showed in the infiltration model validation experiments, the infiltration depths measured were 38.8 cm and 41.1 cm. The relative errors between measured infiltration depth and expected value were 3.1% and 2.7%, respectively, which met the requirement of the soil moisture range consistent with the root boundary. Therefore, this model could be used to determine the optimal irrigation time for developing a sprinkler irrigation control strategy for tea fields in the Yangtze River region.

Permittivity measurement of cementitious materials with an open-ended coaxial probe

This study presents a methodology to investigate the complex permittivity of heterogeneous samples like concrete, mortars and cement pastes by using an open-ended coaxial probe. The probe is associated with portable Vector Network Analyser (VNA) allowing in-situ measurements. Another advantage of the proposed methodology is that the complex permittivity of concrete can be assessed from the measurement of the reflection parameter S11 alone which is innovating in comparison with common devices. This can be achieved by modelling the electrical equivalent circuit of the coaxial probe and the dielectric sample with a capacitive model briefly presented in this paper. A calibration procedure on materials with known permittivity developed to estimate the input parameters of the capacitive model is presented in this paper meanwhile all the details of measurements. Measurements performed on various cementitious materials (cement paste, mortar and concrete) at different degrees of water saturation (from almost dry to fully saturated) show that the probe is able to characterize their dispersive behavior. It is also demonstrated that the probe is able to measure both real and imaginary permittivity of cementitious materials in an extended range of moisture. Relationships are proposed between real or imaginary permittivity and volume water content.

Impact of granule hydration on maize and wheat starch chemical reactivity at the granular and molecular levels

Granular and molecular reaction patterns of maize and wheat starches (normal and waxy genotypes) were investigated in relation to extent of granule hydration (equilibrated at 25, 55, 75, 86 or 100% relative humidity [RH]; moisture range ≈ 10–40 g/100 g starch) within a model reaction system utilizing a fluorescent reagent (5-(4,6-dichlorotriazinyl)aminofluorescein). The greatest incremental increase in granule hydration (49–80%) and overall extent of reaction (30-76-fold) occurred between 86 and 100% RH, likely accentuating the starch glass transition temperature (Tg), which was depressed to room temperature via gradual granule hydration. Under limited hydration conditions (25–86% RH; presumably below Tg), reaction was confined to granule surfaces, whereas under conditions of sufficient hydration/plasticization (100% RH; presumably above Tg), reaction occurred throughout the granule matrix, dramatically increasing reaction of amylose and amylopectin branch chains. For normal starches, amylose was more inert to reaction in low moisture conditions (25–87% RH), indicating either a lesser prevalence at granular surfaces or insufficient hydration to react. Waxy starches exhibited more homogenous granular reaction patterns and greater overall extents of reaction than their respective normal starch counterparts, due to reactivity differences amongst amylose and amylopectin medium and long chains. Findings also provide insights for manipulating granular/molecular reaction locale in “dry” starch modifications.

On Wood–Water Interactions in the Over-Hygroscopic Moisture Range—Mechanisms, Methods, and Influence of Wood Modification

Wood is a hygroscopic material that absorbs and desorbs water to equilibrate to the ambient climate. Within material science, the moisture range from 0 to about 95–98% relative humidity is generally called the hygroscopic moisture range, while the exceeding moisture range is called the over-hygroscopic moisture range. For wood, the dominating mechanisms of moisture sorption are different in these two moisture ranges; in the hygroscopic range, water is primarily bound by hydrogen bonding in cell walls, and, in the over-hygroscopic range, water uptake mainly occurs via capillary condensation outside cell walls in macro voids such as cell lumina and pit chambers. Since large volumes of water can be taken up here, the moisture content in the over-hygroscopic range increases extensively in a very narrow relative humidity range. The over-hygroscopic range is particularly relevant for durability applications since fungal degradation occurs primarily in this moisture range. This review describes the mechanisms behind moisture sorption in the over-hygroscopic moisture range, methods that can be used to study the interactions between wood and water at these high humidity levels, and the current state of knowledge on interactions between modified wood and water. A lack of studies on interactions between modified wood and water in the over-hygroscopic range was identified, and the possibility of combining different methods to acquire information on amount, state, and location of water in modified wood at several well-defined high moisture states was pointed out. Since water potential is an important parameter for fungal growth, such studies could possibly give important clues concerning the mechanisms behind the increased resistance to degradation obtained by wood modification.

Assessing the textural defect of pastiness in dry-cured pork ham using chemical, microstructural, textural and ultrasonic analyses

The dry-cured pork ham industry lacks non-destructive quality control techniques able to characterize relevant textural defects, such as pastiness or softness. The aim of this study is to analyze the feasibility of using different destructive and non-destructive techniques to characterize pastiness in dry-cured ham. Dry-cured ham processing was modified in order to induce different pastiness intensities over a wide range of moisture and salt contents. Afterwards, pastiness was assessed by sensory analysis and samples classified as non-pasty, medium-pasty and highly-pasty. Finally, chemical, textural, microstructural (LM and TEM) and ultrasonic analyses (velocity and attenuation coefficient) were carried out.Samples with a high degree of pastiness experienced an increase of 16.8% and 16.7% as regards the proteolysis index and relaxation capacity, respectively, and a 67.7% decrease in hardness compared to non-pasty hams. The microstructural analysis revealed that pastiness brought about great structural degradation. Ultrasonic velocity was significantly related to the salt (r = 0.79) and moisture contents (r = 0.69), but no influence of pastiness was found on the velocity. However, the attenuation coefficient increased as the pastiness rose and could be considered as a useful parameter for characterizing this complex textural defect. Therefore, ultrasound could be used not only to carry out a non-destructive characterization of dry-cured ham composition but also to assess pastiness.

Multi-step outflow and evaporation experiments – Gaining large undisturbed samples and comparison of the two methods

The aim of the study was the comparison of the soil hydraulic properties determined based on two different experimental methods of four large and macroporous soil samples. An undisturbed cylindrical soil column (h = 60 cm and d = 30 cm) was obtained at a natural slope and quartered horizontally in the laboratory. The four sub-samples were saturated and subsequently drained using the extended multi-step outflow method (XMSO). Retention curves and unsaturated hydraulic conductivity curves were derived via inverse modeling based on the measured drainage and corresponding pore water pressure. After resaturation the evaporation method (EVA) was used on the same four samples. The samples were exposed to evaporation and the effective water contents and the average pore water pressures were recorded over time to determine soil hydraulic functions.While both methods yielded similar results in the medium moisture range, the advantage of the XMSO-method is its higher information content with respect to the hydraulic conductivity close to water saturation whereas the advantage of the EVA-method is its fast execution. Moreover, the EVA-method is easier to handle and has significantly lower computational requirements than the XMSO-method.Furthermore, since the four soil samples represent a soil profile in the field, a depth dependent characterizing of the soil profile was possible and showed that the soil properties near saturation are greatly dominated by the ratio of macropores in the sample and that a decrease in the macropore ratio with soil depth was clearly reflected in the hydraulic functions.

The polarizability of sand-gravel deposits according to the results of laboratory and field measurements

Тhe article describes electrical exploration aimed at studying the polarizability of sand-gravel deposits in the Kaluga region. On the one hand, laboratory tests of the polarizability of sand and sand-gravel mixes (SGM) were carried out, on the other hand, field electrical survey work on the wellknown manifestation of SGM. Samples of SGM were collected from 18 actively operating quarries in the Moscow and Kaluga regions for laboratory petrophysical measurements. Induced polarization (IP) measurements were conducted in time domain. The results showed that sand and gravel mixes are characterized by a rapid process of induced polarization. The minimum values are associated with pure sand samples and the level of polarizability increases with increasing gravel content in the sample. The maximum values of polarizability are achieved when the moisture content of samples is 1,5–2,5%, however SGM samples polarized stronger than pure sand samples all over the moisture range. The field work was performed by the method of vertical electrical soundings with measuring of IP along the well-known sand and gravel deposits in the Kaluga region. The profile step and spacing of the electrical survey installation are selected in such a way as to use the same grounding locations many times. A similar approach is used for multichannel measurements of electrical tomography and allows for further 2D data inversion. The induced polarization was measured in the frequency domain in the frequency range from 0.15 to 19 Hz. The results of the multi-frequency inversion showed the differentiation of the section by the time parameter τ. According to inversion data the geological-geophysical model was constructed. In the section, zones of increased polarizability associated with a gravel-pebble fraction, as well as zones with partial water saturation of sediments were identified. Thus, under the certain favorable conditions, the IP method allows to delineate zones enriched with gravel-pebble fraction within the SGM deposit.