Clay Type Research Articles

Mechanical properties of blended cements affected by impurities in thermally activated clays

Abstract With the scarcity of raw materials, energy intensiveness and environmental burden connected with producing Portland cement, there is a growing need to find substitute binders. Thermally activated clay also appears to be a suitable material for partial cement replacement. However, not all clays are the same. It depends very much on the place of collection, its chemical and phase composition, and the activation temperature. This study compared six different types of clays fired at 600 °C in terms of quantitative phase analysis and mechanical strength results. In addition to the fineness of grinding and firing temperature, the clay composition had an immense impact on mechanical properties. Content of illite up to 20% was found to be beneficial, as this clay reached the highest mechanical strengths. Regarding the quartz, its presence did not harm the overall performance of thermally activated clays and the presence of calcite could cause the improvement of the mechanical strengths. However, the clay with the most miscellaneous composition caused the deterioration of compressive strength but reached much higher bending strength compared to pure cement.

Thermal insulation and X-ray attenuation properties of fired clay-perlite composites

In this work, the expanded perlite (EP) was used as an additive in local Hang Dong (HDC) and San Kham Phang (SPC) clays from Chiang Mai province, Thailand, for wall tile manufacturing and its influence on various properties were investigated. All samples were fabricated by drying and sintering the mixtures at 1100 °C for 8 h. Fired bulk density, shrinkage, water absorption and modulus of rupture were measured. With increasing perlite content, the density showed a decreasing trend (2.16–1.62 g/cm3 for HDC clay and 2.13 to 1.37 g/cm3 for SPC clay) with the corresponding reduction in the modulus of rupture. Both types of clays showed higher water absorbability when more perlite was added, indicating the hygroscopic properties of porous perlite particles. Phase and chemical composition indicated the uniform distribution of pea-pod-like perlite structure in clay matrix with strong interfacial bonding due to chemical reaction between perlite additive and clay matrix. X-ray attenuation coefficient was found to decrease in correspondence with the decreasing trend in density values. The thermal conductivity of perlite-added Hang Dong clay exhibited at least 10 times reduction compared to pure clay, suggesting the excellent insulation behavior. The HDC with 100 and 200 cm3 perlite showed good performance in terms of rupture strength, water absorbability, X-ray attenuation with additional insulation properties. Based on this perlite-clay composite study, the sample could be further optimized for its X-ray shielding application by infiltration with elemental or alloy particles.

Changes in the Properties of Soils Contaminated with Oil Production Water Before and Af ter Treatment with CaO

In the Mexican southeast, hydrocarbon spills and their residues af fect various agricultural sites. A specific case is spills of oil production or congenital waters that cause soil salinization. When soil is contaminated, restorations are regularly carried out based on regulatory limits, but many regions still do not consider the pedological classification, so restorations are not entirely ef fective and, in the case of agricultural soils, reduce your productivity. For these reasons, this study evaluated the cation exchange with CaO applied to four soils contaminated with congenital waters and determined if there are dif ferences in the treatment behavior according to the properties of each soil. It will be found that sandy soils require less treatment time, but have greater ef fects on their properties compared to clay soils, mainly in field capacity, pH, and porosity. Furthermore, it was found that contaminant removal times vary with respect to the type of soil and that this could be related to the amount and type of clay. In the case of congenital water spills, clay soils show a greater increase in electrical conductivity (EC) compared to sandy soils. When remediated with CaO, clay soils needed longer treatment times to reduce EC, but presented fewer changes in their physical and chemical properties. In addition, it was found that, although washing with drinking water is carried out, the treatment with CaO adds alkalinity to the soils, so they must be managed according to the crop to be developed. It is concluded that soils have dif ferent physical and chemical properties, this influences the response they have to an external agent, both when contaminated and when remediated.

Estimation of pore-type distribution utilizing petrophysical data and rock physics modeling on an Iranian carbonate reservoir

Pore types in carbonate reservoirs are more complex than their sandstone counterparts due to the wide spectrum of their depositional environments and their more complicated post-depositional processes. This means that a good knowledge of pore types is vital in determining carbonate formation’s elastic and reservoir properties. This study aims to develop a multi-physics approach to determine pore-type variations in a carbonate reservoir using well log information from one of the oilfields of the Abadan Plain in southwest Iran. Firstly, we determined lithology, porosity, and fluid content by interpreting conventional well logs (gamma ray, resistivity, density, neutron, photoelectric, and P-wave sonic). Then, nuclear magnetic resonance data were used to determine different pore types within the Main Ilam and Sarvak formations. We distinguished between clay, micro, meso, and macro pore types. We confirmed our interpretation results using thin sections, scanning electron microscopy photographs, and pore-size distribution on the available core plugs. Finally, a carbonate rock physics model was employed to model sonic velocities using petrophysical interpretation along with pore-type determination results. A good match between modeled and measured sonic velocities confirmed that using nuclear magnetic resonance data for pore-type determination can reasonably estimate pore-type variations needed for rock physics modeling. The standard industry procedure for carbonate rock physics modeling uses sonic logs, core data, or thin sections to determine pore types. We offer a substitute approach with reasonable accuracy for pore-type modeling needed for carbonate rock physics modeling. We modeled pore types independently from sonic velocity and used them to predict P-wave velocity with a correlation coefficient of 92 and 64 percent accuracy in the Main Ilam and Sarvak formations.Graphical abstract

Electrochemical Impedance Spectroscopy Analysis of Organic Epoxy Coatings Reinforced with Nano Clay.

Electrochemical impedance spectroscopy (EIS) is a modern and efficient method for the evaluation of the protective abilities of coatings. However, the interpretation of the experimental data is a difficult task. This paper aims to investigate the effect of the addition of a nano clay, Cloesite 30B®, on the barrier properties of an epoxy-based system through electrochemical impedance spectroscopy in an aerated sodium chloride solution. The EIS spectra of the samples analysed showed different evolutions over time. The subsequent processing of spectra using equivalent electrical circuits is an excellent analytical tool and allows the protective capacity of coatings to be assessed. By using this analysis, it was possible to define and comprehend the impact of adding nano clay in different concentrations to the epoxy resin coating. The work has shown the effectiveness of increasing the barrier effect of the coating with this type of nano clay. However, the improvement is linked to obtaining a correct dispersion of nanoparticles. Otherwise, there is the formation of macro-clusters of particles inside the coating. Their appearance can cause a deterioration in coating performance.

Investigation on parameters affecting reduction coefficient of groundwater buoyancy in clay layers

The buoyancy of groundwater in clay layers is a critical factor that influences the behavior of geotechnical engineering structures. However, there is still a lack of understanding regarding the factors that contribute to the reduction of groundwater buoyancy. This study aims to elucidate the influence of soil parameters and matric suction on groundwater buoyancy, employing laboratory model tests and innovative experimental methods. The research findings uncover noteworthy variations in the reduction coefficient of groundwater buoyancy contingent upon the clay type, ranging from 0.45 to 0.85. Furthermore, experimental results indicate that matrix suction effectively diminishes pore water pressure but exerts minimal influence on groundwater buoyancy. It is elucidated that pore ratio, permeability coefficient, and water content evince a robust positive correlation with the buoyancy reduction coefficient, whereas dry density and wet density exhibit an inverse trend. Conversely, parameters such as cohesion, saturation, internal friction angle, specific gravity, liquid limit, and plastic limit manifest minimal correlation with the buoyancy reduction coefficient. These findings have practical implications for anti-floating design in geotechnical engineering.

Synthesis and Characterization of Nanocomposite Hydrogels Based on Poly(Sodium 4-Styrene Sulfonate) under Very-High Concentration Regimen of Clays (Bentonite and Kaolinite).

The aim of this work was to synthesize and study the functional properties of polymer-clay nanocomposite (PCNCs) based on poly(sodium 4-styrene sulfonate) (NaPSS) and two types of clay in the dispersed phase: bentonite and kaolinite, in order to advance in the development of new geomimetic materials for agricultural and environmental applications. In this study, the effect of adding high concentrations of clay (10-20 wt. %) on the structural and functional properties of a polymer-clay nanocomposite was evaluated. The characterization by infrared spectroscopy made it possible to show that the PCNCs had a hybrid nature structure through the identification of typical vibration bands of the clay matrix and NaPSS. In addition, scanning electron microscopy allowed us to verify its hybrid composition and an amorphous particle-like morphology. The thermal characterization showed degradation temperatures higher than ~300 °C with Tg values higher than 100 °C and variables depending on the clay contents. In addition, the PCNCs showed a high water-retention capacity (>2900%) and cation exchange capacity (>112 meq/100 g). Finally, the results demonstrated the ability of geomimetic conditioners to mimic the structure and functional properties of soils, suggesting their potential application in improving soil quality for plant growth.

Comprehensive analysis of fine particle migration and swelling: Impacts of salinity, pH, and temperature

About 70% of the world's oil production comes from reservoirs with loose reservoir rock. The looseness of the reservoir rock causes fine particles to move during production. Additionally, there are different types of clays in the reservoir, which have the possibility of swelling in addition to migration. Migration and swelling of fine particles result in increased permeability reduction and formation damage. Identifying the migration and swelling mechanisms of fine particles can prevent the migration and swelling of fine particles in the porous media. As a result, it prevented production reduction and excess production costs and increased the EOR process's efficiency. Salinity, pH, and water temperature changes can significantly affect fine migration and swelling. This research investigates a laboratory's parameters affecting injection water, such as salinity, pH, and temperature. Due to the precision in analyzing the results and a better understanding of the mechanisms, synthetic cores containing fine particles and clays were used. The permeability, turbidity, electron microscope images, and pH data showed that the change in salinity, pH, and temperature disturbs the balance between the rock's surface and fine particles. With the decrease of salinity below the critical concentration of salt, permeability reduction and turbidity were observed. In this case, the dominant mechanism was the migration of fine and clay particles. When the pH of the injection fluid increased, the permeability reduction increased, the turbidity decreased, and the predominant mechanism was the swelling of fine particles. An increase in temperature also caused an increase in permeability reduction and turbidity. The mechanisms of migration and swelling were supposed to be simultaneous with the temperature rise.

Emergence and Phenological Development of Herbicide-Sensitive and Herbicide-Resistant Biotypes of Apera Spica-Venti and Winter Wheat under Competition

As a result of intensive herbicide protection of crops against silky bentgrass (Apera spica-venti (L.) P. Beauv), numerous herbicide-resistant biotypes have been selected, mainly from the group of acetolactate synthase (ALS) inhibitors. We analyzed the development of herbicide-sensitive and herbicide-resistant biotypes of bentgrass and winter wheat under competition, taking into account selected physical and chemical properties of the soil, including nitrogen fertilization. The pot experiment (additive model) was conducted in the 2018/19 and 2019/20 seasons. The experimental factors included: (1) bentgrass with different sensitivity levels to herbicides from the groups HRAC/WSSA 1 and HRAC/WSSA 2, specifically two sensitive and three resistant biotypes; (2) two types of soil, sandy and clay; and (3) nitrogen fertilization, both with and without fertilization. Winter wheat and bentgrass development was assessed during each growing season, every 5 or 3 days from September until May, using the BBCH scale. The emergence date of the tested species/biotypes was recorded. The development of competing species was compared based on a new, proposed index: the duration of the developmental phases. As a result, the soil type and fertilization level differentiated wheat and bentgrass emergence dates and development. The autumn development of the competing species was slower and more uniform than the spring one. At the same time, the dynamics of the bentgrass and wheat development in the spring were greater. Bentgrass and winter wheat emerged earlier and grew more intensively on clay and fertilized soil. To sum up, no clear relationship was found between the resistance/sensitivity of bentgrass to herbicides and changes in the phenological development of plants in competition with winter wheat.

Effect of pore-bearing fluids on the mechanical behavior of siliceous cemented sandstones containing different clay contents and types

The clay minerals contained in the reservoir rock of CO2 geological storage formations can adsorb fluids and swell, which weakens the rock and promotes deformation. This phenomenon has not been widely investigated due to the complexity of the mineral components of the rock. To study the relationship between fluids in rock pores and the mechanical behavior of clay-bearing reservoir rocks, three types of siliceous cemented sandstones mainly composed of clay minerals and quartz, both dry and saturated with various fluids (i.e. N2, scCO2, H2O), were subjected to conventional triaxial compression tests. The results show that the fluids weakened the mechanical strength of the sandstones, and the degree of weakening depended on the clay composition and the type of fluid, with no significant relationship to the clay content. For the sandstone containing montmorillonite, compared to the dry condition, scCO2 and H2O reduced the peak strength by up to 7.16% and 15.33%, respectively, while for the sandstone containing only kaolinite as clay component, scCO2 and H2O reduced the peak strength by 3.34% and 3.18%, respectively. As a control, N2 weakened the strength of the three types of sandstones between 1.46% and 4.04%. By considering the failure characteristics of sandstone at the macro- and microscales, the failure mechanism of the sandstones was explained from two perspectives: the intercrack surface energy reduction and the swelling of clay. This study offers new perspectives for assessing the mechanical stability of fluid-bearing reservoirs and clarifies the role of clay in the connection between fluids in rock pores and the mechanical behavior of rocks.

Clay influence on lightweight brick’s properties: Investigating the impact of waste’s nature and amount as secondary variables

The present study aims to examine whether incorporating a specific proportion of a particular waste material consistently yields bricks with favorable properties, regardless of the raw clay type utilized. In this context, different mixtures were produced with a clay named AMD2 and 0 wt%, 5 wt% and 10 wt% addition of two wastes named argan nut shell and wheat straw. A first investigation of the used raw clay material revealed the presence of Quartz as a dominant mineral, along with Orthoclase, Illite, and Hematite. Furthermore, the elaborated bricks have been subjected to a physical, mechanical, and structural characterization including loss on ignition (LOI), linear shrinkage (LS), water absorption (WA), apparent porosity (AP), bulk density (BD), and compressive strength (CS). A comparison between the current study and a previous one using the same waste materials and identical proportions of addition but employing a different clay type revealed notable differences in outcomes. In the previous study, bricks fabricated with AMD1 clay and 5 wt% of argan nut shell displayed excellent characteristics. However, in the current investigation using AMD2 clay, bricks with the same waste addition ratio exhibited less favorable properties. Specifically, bricks made with AMD2 clay and 5 wt% argan nut shell showed a loss on ignition of 7.30 %, a linear shrinkage of 3.7 %, a water absorption of 23.3 %, an apparent porosity of 38.20 %, a bulk density of 1.64 g/cm3, and a compressive strength of 9.90 MPa. These outcomes indicated a water absorption above the specified limit and significantly higher apparent porosity compared to bricks produced with AMD1 and 5 wt% argan nut shell, which met standard specifications. This variation highlights how the mineral composition of clay significantly impacts brick properties, even when using the same waste materials and proportions, confirming the importance of considering the raw clay material's nature in bricks’ production, and thus emphasizing the need for a preliminary study before combining clay and wastes in order to achieve excellent results.

Combined use of kaolin and bentonite molding clays

The article compares the properties of kaolin and bentonite clays. It has been shown that kaolin clays have high fire resistance, and bentonites have high astringent properties. The experience of specialists from OJSC “MTW” in the joint use of various types of clays is considered. The combination of kaolin and bentonite in the suspension made it possible to increase the strength of the molding sand while maintaining moisture levels. The disadvantage of kaolin clay suspensions is that the moisture content increases with increasing dosage. When preparing bentonite suspensions, their short shelf life should be taken into account.

Two-dimensional experimental assessment of interaction energy-induced suffusion in sand-clay mixtures

Suffusion can be defined as the loss of relatively small soil particles in gap-graded soils without any volume change. This study investigates the susceptibility of interaction energy-induced suffusion in sand-clay mixtures through laboratory-scale two-dimensional flow cell. The filtrated clay during the injection was measured at three outlets to assess the gravity and reattachment effects as a function of clay type (kaolinite, illite, and bentonite) and sand grain size. It was found that the settling of detached clay particles and the reattachment effect during their transport through the sand medium is a strong function of the swelling potential of clay and the size ratio between sand and clay. In addition, observed particle size distributions of clay at the outlet demonstrated that the relatively small and large clay particles are susceptible to suffusion for non-swelling and swelling clay respectively. The comparison of total filtrated clay between two-dimensional flow cell and the typical soil-column experiments (one-dimensional flow) revealed a high chance of underestimating suffusion using soil-column experiments to assess the suffusion of sand-clay mixtures.

Surface conductivity of clays

SUMMARY Clay minerals are extensively used in a wide range of applications. In particular, clay-bearing formations are considered as suitable radioactive waste repository. Electrical resistivity tomography is an appropriate tool to monitor the properties of clay-bearing locations. However, an inherent drawback of a conventional resistivity survey is its ambiguity in distinguishing between the effects of groundwater salinity, clay content and porosity. A discrimination can be achieved on the basis of the induced polarization method that provides a complex conductivity. The main purpose of this study is the investigation of the complex conductivity of clay samples with a special focus on the contribution of surface conductivity produced by an excess of ions in the electrical double-layer coating the solid particles. Six clay mixtures were selected that include an almost pure kaolinite sample, a sample consisting of a mixture of kaolinite, illite and smectite, a crushed saponite breccia, a Ca-bentonite sample and two illite clay samples. Besides the enriched kaolinite, the other samples are natural geomaterials that contain more than 40 weight per cent clay minerals. The mineralogical compositions of the samples were determined by quantitative X-ray diffraction analysis. The clay powder was mixed with a varying volume of sodium chloride solution to get plastic state clay samples with varying water content. The samples were investigated by the spectral induced polarization method in a frequency range between 1 mHz and 1 kHz. The resulting complex conductivity spectra indicate a decrease of the real part of the electrical conductivity with rising water content for the illite, bentonite and saponite breccia samples. The overall conductivity of these clay samples is dominated by their surface conductivity. In contrast, the electrical conductivity of kaolinite and kaolinite–illite mixture does not show any significant changes with the water content. For all samples, the imaginary part of electrical conductivity increases at low water content. The real part of the surface conductivity indicates a linear dependence on the volumetric clay content. The slope of this linear relationship can be used to distinguish the types of clay. The ratio between imaginary conductivity and surface conductivity, which decreases with increasing clay content, proves to be a suitable parameter that characterizes the connectivity of clay aggregates in the sample. The surface conductivity of the pure kaolinite sample has been determined in an additional multisalinity experiment. The resulting surface conductivity is in good agreement with the experiment of varying water content. The multisalinity experiment has shown that the resulting petrophysical parameters depend on the procedure of sample packing, which may lead to anisotropy. The effect of anisotropy is attributed to the alignment of the plate-like kaolinite particles in the course of the packing and consolidation procedure.

Analisis Kelayakan Tanah Dasar Sebagai Subgrade Jalan Ditinjau Dari Kualitas Daya Dukung Tanah (Studi Kasus Ruas Jalan Anggrek Kota Kupang)

An area's function changes as a result of development, which is followed by an increase in vehicle traffic but not enough road capacity. This causes the road to break down quickly because the carrying capacity of the soil isn't strong enough to handle the volume of vehicles crossing it. The road construction will quickly suffer damage if the subgrade has a low carrying capacity. The current damage to the Anggrek road makes driving uncomfortable from a visual perspective. The road section was damaged, according to field observations, with crocodile skin cracks, longitudinal cracks, subsidence, furrows, and potholes. Based on laboratory tests, the purpose of this study was to examine the damage to the Anggrek road caused by the quality of the soil's carrying capacity. The quantitative analysis and interpretation of the soil test result data is the research method. The analysis reveals that the subgrade soil on the Anggrek road in Kupang City is of the fine-grained organic clay type and has moderate to high plasticity. It is also easily influenced by water and the season or weather, so the water content can easily rise or fall. It is also easy to change the volume of soil content depending on the water content. The CBR value of the soil is low, and it does not meet the requirements outlined in the BM Specifications 2018 Rev 2 of 2020. The assessment

Assessment of Durability of Chemically Stabilized Soils Using Different Moisture-Susceptible Methods

The durability of chemically treated subgrade soils is important for pavement design life, and it is a major concern for transportation and defense agencies. Stabilized soil layers should retain strength and stiffness properties under wetting–drying-related durability cycles and moisture exposure. Many durability test methods, including wetting and drying, tube suction, and Engineer Research and Development Center’s wet-test methods, have been developed and used in several stabilization studies in the past. It is important to study and determine how these methods address the long-term performance of chemically stabilized soils with a focus on stabilizer permanency. Therefore, this research study conducted a comprehensive laboratory investigation using all three methods to assess the durability of stabilized soils as per the US Department of Defense protocols. Three types of soils, silty sand, clayey sand, and high-plasticity clay, and three types of stabilizers, vinyl acetate-ethylene (VAE) copolymer, Portland cement type I, and hydrated lime, were considered in this study. Silty sand, clayey sand, and high-plasticity clay soils were treated with VAE copolymer, cement, and lime, respectively. Results of cement-stabilized soil showed that it is unsusceptible to moisture fluctuations, whereas VAE-stabilized soil indicated its higher susceptibility to moisture variations. Both the ASTM wet–dry (W-D) test and tube suction test methods revealed that lime-treated clayey soil is moisture-susceptible. All three methods showed similar findings, with good agreement existing between tube suction and ASTM W-D tests for all combinations of soils and stabilizers considered in this study.

The Impact of an Earthworm Digestion on the Chemical Compositions of Various Clay Minerals from Soils

Aims: The impact of living organisms activities in soils may generate various chemical and mineralogical changes. The objective of this study is to estimate the impact of earthworms on the chemistry of soil minerals such as the clay minerals. Study Design: An experiment was carried out integrating earthworms and clay minerals. The modifications due to this interaction between minerals and organic matter induced by earthworms’ digestion are discussed. Place and Duration of Study: Institut des Sciences de la Terre et de l’Environnement (UdS/CNRS), Université de Strasbourg, Strasbourg, France. Eight weeks of experiment for each type of clay. Methodology: The earthworm Lumbricus terrestris was used for digestion of illite and various smectite-type minerals, with or without peat moss, during a laboratory experiment at a constant temperature of 20°C during 8 weeks and under artificial 12 hour-light and 12 hour-dark cycles, for each digestion cycle. Results: The chemical elements extracted from smectites by the earthworm digestion appear to be mineral dependent. The behavior of K and radiogenic 40Ar is more dictated by the type of digested mineral than by the digestion process itself. The 87Sr/86Sr ratio of the acid leachates of the nontronite and peat mixture, before and after digestion, suggests that half of the digested matter corresponds to the digestive action of the earthworms, with the second half resulting from food. Digested clay material represents up to 30% and the peat moss the remainder of the mixtures. Conclusion: This study highlights the role of organic compounds generated by earthworms activities in transfer of elements to surface waters and soil fluids.

Study on Sensitivity Mechanism of Low-Permeability Sandstone Reservoir in Huilu Area of Pearl River Mouth Basin

Reservoir sensitivity is a parameter that is used to evaluate the degree of change in reservoir permeability under the influence of external fluids. Accurate evaluation of reservoir sensitivity is conducive to the optimization of fluid parameters during exploration and development. Taking the Wenchang Formation and Enping Formation of the Paleogene in the Huilu area of the Pearl River Mouth Basin as the research object, reservoir sensitivity experiments were carried out. Combined with the corresponding experimental results obtained using methods such as thin section identification, scanning electron microscopy (SEM), X-ray diffraction (XRD), mercury intrusion porosimetry (MIP), and screening analysis, based on mineral sensitization and pore structure sensitization, qualitative and quantitative evaluations of reservoir sensitivity were carried out, and factors affecting sensitivity and sensitization mechanisms were analyzed. This work shows the following: (1) The sandstone reservoirs in the two areas have the same clay type, but the total clay content of the Wenchang Formation is greater than that of the Enping Formation. The porosity of the Wenchang Formation is less developed than the Enping Formation. (2) The Wenchang Formation has weak or moderately weak water sensitivity and moderately weak or moderately strong flow velocity sensitivity. The water sensitivity of the Enping Group samples is moderately weak or moderately strong, the flow rate sensitivity is moderately weak, the alkali sensitivity is weak, the acid sensitivity is moderately weak, and the salinity sensitivity is moderately weak or moderately strong. (3) The sensitivity of the Wenchang Formation is mainly affected by the content of clay minerals. The sensitivity of the Enping Formation is also affected by the clay content and type. Although the clay content is not high, the permeability is more susceptible to sensitivity due to the pore structure and debris particle distribution characteristics. These conclusions are beneficial for the selection of fluid parameters and efficient reservoir development.

Exploring the feasibility of utilizing high plastic clays as an alternative material to bentonite clay in the production of ceramic tile: Advancing towards efficient life cycle cost

The environmental challenges and high cost of raw materials (i.e., bentonite clays) for the production of ceramic tiles raise concerns for the ceramic industry to look for alternative materials. Therefore, the current research aimed at exploring the possibility of using high plastic clays as a replacement for Bentonite clay in the manufacturing of ceramic tiles. Two different types of high plastic clay in different proportions (i.e. 0–5 %) were used in the preparation of ceramic tiles. A comprehensive material characterization, shrinkage, visual index, flexural strength, water absorption, and microstructural investigation was carried out. The results revealed that the incorporation of plastic clays RC1 from 1 % to 5 % showed a decrease in the flexural strength of ceramic tiles as compared to that of ceramic tiles with bentonite clay. The water absorption of ceramic tiles using RC1 increased with the incorporation of high plastic clays for high plastic clays. However, specimens with all replacements of bentonite clay with high plastic clays showed flexural strength greater than the minimum specified limit of ISO 10545-4. Moreover, it was observed that the replacement of bentonite clay with high plastic clays exhibited higher shrinkage. Further, the visual index of all the specimens did not show any sign of the presence of black core in the ceramic tiles incorporating high plastic clays. The life cycle assessment (LCA) was carried out for the possible utilization of high plastic clays in place of bentonite clay to produce ceramic tiles. The results showed that less than 5 % high plastic clay can effectively be used for manufacturing ceramic tiles leading to economical and sustainable construction products. Hence, it can be concluded that the high plastic clays can be utilized as an alternative to bentonite clay material for manufacturing sustainable ceramic tile leading to sustainable finishes in construction.

Rheo-SAXS study of a shear-thinning hydrogel containing clay nanoplatelets

Shear-induced orientation of clay nanoplatelets within a physically cross-linked hydrogel based on ionenes, positively charged polyelectrolytes, is studied here. Small angle X-ray scattering measurements (SAXS) are performed under shear within a Couette cell cylinder (rheo-SAXS). As the SAXS signal is dominated by that of the clay component, we follow the evolution of the orientational distribution of the clay nanoplatelets within the hydrogel as a function of shear. We investigate the effect of the clay volume fraction, polyelectrolyte concentration, clay charge location and clay charge density by screening three different types of clay: Wyoming and Arizona montmorillonites and Idaho beidellite. The orientational field of clay nanoplatelets in the gel is shown to strongly depend on the clay charge location and shear rate, whereas it is independent of the clay volume fraction. Approaching the critical gelation concentration of the polyelectrolyte system, these features change drastically.