Characterization of expansive soils for the foundation of an irrigation canal in the Peruvian Andes, Cabana-Mañazo case

Alterations in water content in swelling soils cause volume variation, which implies constructive, socioeconomic and environmental damage. This paper characterizes the swelling soil located in an irrigation canal of the Peruvian Altiplano and its behavior of the properties by addition of lime in 5, 10, 15 and 20% of the total weight. Finding that the sample of the station 6+575 has combined presence of montmorillonite clays in a percentage of 13.52% together with the group of kaolinites in a percentage of 1.31%, consequently, it makes expandable clay of high plasticity. The soils of the station 6+250 have the characteristics of kaolinite clay, which distinguishes it as having low plasticity. In the swelling tests the high expansiveness was found, in the station 6+575, which has decreased with the addition of lime. Considering that concrete canals are generally of small thickness it would be important to consider the slightly dangerous effects on irrigation infrastructure.

MECHANICAL PROPERTIES AND WEAR BEHAVIOUR OF KAOLINITE CLAY PARTICLES REINFORCED EPOXY MATRIX COMPOSITES

Epoxy matrix composites reinforced with clay particles were developed by hand lay-up open mould casting technique. The clay used in this study was pulverized and processed into ultrafine particles through the sedimentation process. The composites were developed by blending the epoxy matrix and hardener with various weight fractions of the ultrafine clay particles (2, 4, 6, 8 and 10 wt%) in open test moulds. In order to accomplish a homogeneous blend of the constituents; manual mixing of the blend was carried out for 3 min. The test specimens were left to cure for 24 hours in the moulds and for additional 27 days at room temperature of 27 ± 2 °C and were thereafter detached from the moulds. The developed composites test specimens were subjected to mechanical tests (flexural, tensile and impact) in accordance with ASTM standards and performed at room temperature. Structural characteristics of the clay particles were determined with the aid of an X-ray diffractometer (XRD). The morphologies of the composites were determined using a scanning electron microscope (SEM). There was a progressive enhancement in the mechanical properties of epoxy composites containing 2-6 wt.% ultrafine clay particles while a drastic decrease in the mechanical properties was noticed in the epoxy/clay composites reinforced with 8-10 wt.% ultrafine clay particles. The SEM images revealed homogeneous particles distributions within the epoxy matrix at lower ultrafine clay particles weight fractions (2 wt. % and 6 wt.%).

Amending Potassic Fertilizer with Charcoal and Sago (Metroxylon sagu) Bark Ash to Improve Potassium Availability in a Tropical Acid Soil

In Ultisols and Oxisols, potassium (K) in the soil solution is leached from the rhizosphere before it interacts with soil colloids, or exchanged with other cations at the exchange sites of the soils because of the abundance of kaolinite clay minerals. These soils are highly weathered, low in organic matter, and low in pH, but high aluminium (Al) and iron (Fe) ions. Hence, K becomes unavailable for plants, and this compromises crop production and farmers’ profitability. The pH neutralizing effects of sago (Metroxylon sagu) bark ash and the ability of charcoal to chelate Al and Fe could be utilized to improve soil pH, reduce soil acidity, and improve K availability. The objective of this study was to determine the effects of amending muriate of potash (MOP) with charcoal and sago bark ash on selected soil chemical properties in a tropical acid soil (Typic Paleudults) over 90 days in a laboratory incubation. The proportions of charcoal and sago bark ash were varied at 20%, 40%, 60%, 80%, and 100%, but the MOP was fixed at 100% of the recommended rate. Selected soil chemical properties before and after incubation were determined using standard procedures. Results revealed that co-application of the soil amendments with MOP increased soil-exchangeable K compared with conventional practice. Moreover, amending the acid soil with charcoal and sago bark ash positively enhanced the availability of other base cations and soil cation exchange capacity (CEC). This was possible because the amendments increased soil pH and reduced exchangeable acidity, exchangeable Al3+, and exchangeable Fe2+. However, there was no significant improvement in water-soluble K (WSK) in the soil with or without charcoal and sago bark over the 90 days laboratory study. The findings of this study suggested that increasing soil pH could potentially improve soil K sorption capacity. Thus, the optimum rates of charcoal and sago bark ash to increase K availability were found to be 80% charcoal with 80% sago bark ash, 60% charcoal with 60% sago bark ash, and 80% charcoal with 40% sago bark ash, because these rates improved soil-exchangeable K+ and CEC significantly, besides minimizing soil-exchangeable acidity.

Adsorption of anionic surfactant on surface of reservoir minerals in alkaline-surfactant-polymer system

Alkaline-surfactant-polymer (ASP) flooding is significant to the oil and gas industry due to synergistic interaction between alkaline, surfactant and polymer. However, chemical losses due to adsorptions of surfactant and polymer on the rock surface could lead to inefficiency of the process. There are also significant uncertainties on adsorption mechanism when surfactant is flooded with presence of alkaline and polymer. This study highlights the static adsorption tests using anionic sodium dodecyl sulphate (SDS), hydrolysed polyacrylamide (HPAM) and sodium carbonate (Na2CO3) as the surfactant, polymer and alkaline, respectively. Sand particles and kaolinite clay were used as the reservoir minerals. The adsorption tests were conducted at various surfactant concentrations ranging from 50 to 2000 ppm. Sodium chloride (NaCl) concentration was investigated from 0 to 2 wt.%, while the local sand and kaolinite was mixed in surfactant solution at a fixed mass to volume ratio of 1:5. The static adsorption test was conducted by shaking the mixture samples and centrifugation before analysing the supernatant liquid using UV-Visible spectrophotometer. The results showed that the surfactant adsorption was higher on kaolinite compared to sand particle. The higher the salinity, the higher the adsorption of surfactant due to higher ionic strength. The adsorption of SDS surfactant on sand particles and kaolinite was lesser in ASP system compared to the presence of surfactant solution alone. Thus, it can be concluded that the presence of polymer and alkaline in ASP solution have great potential to reduce the surfactant adsorption on both sand particle and kaolinite.

Kaolinite clays as a source of raw materials for the aluminum industry of the Republic of Kazakhstan

Kaolinite clays can serve as an additional source of alumina in the Republic of Kazakhstan. The most promising is the Alekseevsky kaolinite deposit. To obtain high-quality kaolinite and quartzite products, it is necessary to develop special enrichment techniques, since no satisfactory results were achieved when using standard methods of gravitational enrichment of kaolinites. The paper presents the results of studies of the effect of preliminary chemical activation during the processing of kaolinite clays of the Alekseevsky deposit. Previously, the method of preliminary chemical activation of raw materials in a solution of sodium bicarbonate has proven itself well in the processing of various mineral raw materials. It was determined that during the preliminary chemical activation in a solution of sodium bicarbonate, changes occurred in the phase composition of the kaolinite fraction: the content of muscovite decreased almost twice; the phase of sodium aluminosilicate was formed. The dependence of the yield of Al2O3 in the kaolinite fraction on the temperature of chemical activation, duration, and the ratio of L:S and the concentration of the sodium bicarbonate solution during chemical activation. The optimal mode of preliminary chemical activation of kaolinite clay of the Alekseevsky deposit has been established: the temperature is 150 oC, the duration is 120 minutes and the concentration of sodium bicarbonate solution is 120 g/dm3. A basic technological scheme is proposed for the processing of kaolinite clays.

Co-Application of Charcoal and Wood Ash to Improve Potassium Availability in Tropical Mineral Acid Soils

Potassium (K) is a macronutrient required by plants for energy production, enzyme activation, formation of cell wall, production of protein, and photosynthesis. However, K in the soil solution is leached from the rhizosphere before it interacts with soil colloids because of the abundance of kaolinite clay minerals in mineral acid soils such as Ultisols and Oxisols. These soils are highly weathered, low in organic matter, low in pH, but high aluminium (Al), and iron (Fe) ions. As a result, K becomes unavailable for plants, and this affects crop production and farmers’ profitability. This problem has steered the attention to the application of amendments to minimise K loss. Animal manures, plant residues, and composts applications are some of the corrective measures taken to improve the K availability in tropical acid soils. However, there is dearth of information on co-application of charcoal and wood ash as soil amendments to improve the K availability and the changes they cause to the dynamic equilibrium of K in mineral acid soils. Hence, this review discusses the dynamics, availability of K, and proposed mechanisms involved when charcoal and wood ash are used to amend tropical acid soils. The optimisation and understanding of the role of charcoal and wood ash co-application as soil amendments have potential benefits to improve the K availability and physicochemical properties of mineral acid soils.

The influence of lime powder on the behaviour of clay soil

High price of land and importance of modern construction has imposed the need to strengthen weak clay soils. The stabilization of these soils has been conducted using various additives. Due to its low cost, availability, and positive impact on resistance, lime has traditionally been applied for stabilisation of poor and sensitive types of soils. In this research, lime powder, added in the percentages of 0, 2, 4, 8 and 16 of the dry soil weight, was mixed with kaolinite clay soil and its various engineering parameters were investigated during the curing time of 90 days. PH change, Atterberg Limits, optimum water content, and the modified clay maximum dry unit weight, were determined at different percentages of lime during the curing time. In the scope of determination of an optimum lime powder content, the Unconfined Compressive Strength tests (UCS) and CBR tests were conducted. The Young’s modulus was determined based on UCS testing and definition of stress-strain curve. The results showed a significant increase in the effective, responsive performance of lime in the soil and a remarkable increase in the maximum compressive strength (qu), cohesion, and Young’s modulus.

The Synergic Effect of Whey-Based Hydrogel Amendment on Soil Water Holding Capacity and Availability of Nutrients for More Efficient Valorization of Dairy By-Products

Agricultural production is influenced by the water content in the soil and the availability of nutrients. Recently, changes in the quantity and seasonal water availability are expected to impact agriculture due to climate change. This study aimed to test an agricultural product with promising properties to improve soil quality and water-holding capacity during agricultural application. Most of the traditional hydrogels are low-biodegradable synthetic materials with under-researched long-term fate in field soil conditions. The novel, biodegradable hydrogel made from acid whey and cellulose derivatives cross-linked with citric acid was used. The soil-improving effects were tested under controlled experimental conditions with the sandy artificial soil consisting of 10% finely ground sphagnum peat, 20% kaolinite clay, and 70% quartz sand. Soil pH, the content of organic carbon (Cox), total nitrogen (N), available forms of the essential macronutrients (P, K, Ca, and Mg), the cation exchange capacity (CEC), the maximum water capacity (MWC) and water holding capacity (WHC) were determined. The results showed a positive effect on water retention and basic soil properties after the different levels of hydrogel had been introduced into the soil. Generally, the addition of whey-based hydrogel increases the available nutrients concentration and water retention in soil.