Hard Clay Research Articles

Bearing Capacity Parameters for Pipe Piles in Stiff to Hard Highly Plastic Clays

The design of steel pipe piles in clay soils is faced with insufficient information regarding the parameters used forestimation of their static ultimate load capacity, namely the adhesion factor and plug length.This paper gives guides forthe selection of the mentioned parameters. Direct shear and adhesion tests were performed. The soil tested is highly plasticsilty clay statically compacted in the shear box at constant dry density and varying water content covering dry and wet ofoptimum water content. The adhesion factorwas computed for each test condition. An average value of 0.48 was foundfor the interface resistance when the water content is lower than the plastic limit. The factor was found to increase withincrease in water content for water content higher than the plastic limit.The Plug length data was generated from a construction site in Melut Basin in Southern Sudanwhere steel pipe piles of differentsizes were driven in very stiff to hard silty clay to about the same length and driving records were recorded with extra dataregarding plug lengths. Geotechnical investigation preceded the construction activities. The plug data was analyzed for theeffects of pile diameter and soil conditions on the plug length. Plug length to diameter ratio ranged between 3.8 and 8.0. Pluglength increased linearly with increasing pile diameter and an excellent linear relationship was obtained between the averageplug length for each diameter and pile diameter. Piles with small diameter gave lower resistance to penetration compared withthose with larger diameters.

Quantitative estimations of iron oxide minerals in the Late Pleistocene paleosol of the Yangtze River Delta: Implications for the chemical weathering, sedimentary environment, and burial conditions

Iron oxide minerals are widely present in soil and known to be closely associated with soil-forming environments. In this study, a detailed quantitative analysis of the iron oxide minerals in the Late Pleistocene hard clay of the Yangtze River Delta (YRD) was conducted using new integrated methods of magnetism, selective chemical-dissolution, and diffuse reflectance spectroscopy. A variety of established chemical weathering indexes and optically stimulated luminescence (OSL) chronology were also applied in the investigations of the hard clay in the study area. These methods allowed for detailed examinations of the chemical weathering, sedimentary environmental conditions, and the post-depositional processes of the hard clay deposits in the YRD. This study’s A-CN-K diagram revealed that the hard clay had entered an intermediate weathering stage. In addition, various chemical weathering indexes demonstrated that the hard clay had undergone three stages of chemical weathering from bottom to top as follows: 1) A relatively high stage of chemical weathering; 2) A low chemical weathering stage with a slightly increasing trend; and 3) A relatively high chemical weathering stage with a weakly decreasing trend. It was found that when χ, χfd, Fed/Fet, Gt, and Hm/Gt were not reliable indicators of chemical weathering for the hard clay, Fed could be a useful proxy. In the current study, based on the OSL ages and several paleoclimatic proxies, it was suggested that the climate conditions in the YRD had transitioned from a relatively weak to a strong East Asian summer monsoon phase during the periods between the marine oxygen isotope stages (MIS) 4 and MIS 3. Furthermore, the low values of χ and χfd in the hard clay indicated an intense dissolution of fine-grained strong magnetic minerals. Meanwhile, the relatively high Feo/Fed ratios in the superficial horizon displayed the predominance of poorly crystalline forms of iron oxides. In summary, the analysis results implied that the hard clay had undergone post-burial processes of ferrolysis, as well as dissolved organic matter translocation from the overlying Holocene sediment. The aforementioned post-burial processes for the hard clay had occurred under reduction–oxidation cycles, which were mainly driven by the rise of the groundwater levels with the Holocene transgression.

Drivers of Hot Spots and Hot Moments of Denitrification in Agricultural Systems

AbstractDenitrification, the most poorly understood process in the nitrogen (N) cycle, is of great interest as it can significantly reduce pools of reactive N and act as a source of the potent greenhouse gas nitrous oxide (N2O). A particular study challenge is that small areas (hot spots) and brief periods (hot moments) of denitrification frequently account for a high percentage of N gas flux activity. Our study utilized sites within the U.S. Department of Agriculture Long‐Term Agroecosystem Research (LTAR) Network to understand the importance of potential drivers of such hot spots and hot moments of denitrification in agricultural systems. We quantified in situ denitrification rates in intact soil cores from three LTAR sites – Upper Chesapeake Bay (UCB), PA, Central Mississippi River Basin (CMRB), MO, and Gulf Atlantic Coastal Plain (GACP), GA – by directly measuring dinitrogen (N2) and N2O production via the Nitrogen‐Free Air Recirculation Method (N‐FARM). Each site provided an opportunity to study a different potential driver of denitrification: landscape‐scale topography (UCB), soil confining layers (CMRB), and ecosystem‐scale climate (e.g., drying‐rewetting events; GACP). At the UCB site, wetter, low topographic positions released a higher proportion of N2:N2O, suggesting that N removal does not result in increased greenhouse emissions. Results at the CMRB site show evidence that confining features, like hard clays, could drive denitrification hot spots. Similarly, such features at the GACP site could drive denitrification hot spots (at depth) and hot moments (drying‐rewetting). These results suggest that denitrification is a significant sink for excess agricultural N at multiple scales, which may inform management decisions in the future.

Investigation of Soft Layer in between Hard Layer for Sedimentary Rock Formation by using Electrical Resistivity Analysis

This study aims to predict the occurrences of soft layers in between hard layers in sedimentary rock formation based on electrical resistivity analysis. ABEM Terrameter LS Box with 40 electrodes with 2.5 meters spacing in pole-dipole method was used. Standard Penetration Test (SPT) was conducted to obtain the value for the number of blows (N-value). RES2DINV was used to analyse a two-dimensional illustration of the soil layers in the pseudo section diagram. Results show that the groundwater table is located 2.0 meters below the ground surface. Based on the resistivity analysis, the subsurface profile is consists of topsoil, soft silty clay (N0-N4, 6 > Ω > 20 ohm), medium-stiff silty clay (N5-N6, 20>Ω>360 ohm), medium dense coarse sands (N13-N16, 361>Ω>550 ohm), stiff silty clay (N10-N18, 550>Ω>720 ohm), hard silty clay and gravel (N50, 720>Ω>1100 ohm), and moderate weathered and slightly fractured shale stone (N50, Ω>1100 ohm). Although the correlation between resistivity values and SPT N-values shows a very good relationship with R2 ranges from 0.83 to 0.89, electrical resistivity analysis is not suitable to determine the soft layer in between hard layer in a sedimentary rock formation due to the presence of high ground water table.

Sedimentary characteristics and evolution process of the Huangqiao sand body in the Yangtze River Delta, China

Sea-level rise and reduced sediment loads have caused erosion in the Yangtze River Delta, which is one of South Asia's largest deltas. Scholars have not reached a consensus regarding the origin and timing of the Yangtze River Delta formation, mainly because of the scarcity of cores at the bottom of the delta. In this study, we recovered three sediment cores from the Huangqiao sand body. We systematically analyzed their parameters, including sedimentary characteristics, down-core changes in grain size, benthic foraminifera and ostracod assemblages, AMS14C dating, and optically stimulated luminescence dating. We also integrated our results obtained with data from previously studied cores of the Yangtze River Delta. Four depositional systems were identified in the Huangqiao sand body: a fluvial system dated 12–10 ka that includes sandy gravel in incised valleys and hard clay in paleo-interfluves; an estuary dated 10–7.5 ka that is characterized by sand-mud couplets in valleys and tidal floodplains in the other regions; a deltaic system dated 7.5–4 ka; and a delta or estuary dated 4–0 ka, which included tidal flat and delta plains. The stratigraphic architecture and origin of the paleo-Yangtze estuary (bottom of the delta) were mainly controlled by Holocene sea-level changes. The timing of transgression at the bottom of the Yangtze River Delta was different due to differences in the post-glacial paleontography during the early Holocene. Compared to the Yangtze River Delta records, the Huangqiao sand body lies between 7.5 and 4 ka. The age of the main body was affected by sea-level fluctuations and developed from 5 to 4 ka with sediment loads carried by the Yangtze River. The Huangqiao sand body is not an estuarine sand body but a sand body formed in a tide-dominated delta. This study provides new evidence for interpreting the origin and evolution of the Yangtze River Delta.

Numerical investigations of the effects of different factors on the displacement of energy pile under the thermo-mechanical loads

The displacement characteristics of energy pile are very important for its safe and sustainable operation. In order to obtain the influences of various factors on the displacement of energy pile, a thermo-mechanical coupled numerical model of energy pile with groundwater advection was established based on COMSOL Multiphysics software. The effects of thermal load, thermo-mechanical coupling load, groundwater advection, soil type, soil stratification and cooling and heating cycle operation on the displacement variation of energy pile operated in summer and winter modes were studied. The results indicate that for thermal load alone, the pile displacement in summer mode can almost be restored to its initial state, and an irrecoverable pile head displacement will occur in winter mode. The lower the inlet temperature, the larger the displacement variation degree. For the thermo-mechanical coupling load, the change ratio of pile head displacement increases with the decrease of mechanical load and increases with the increase of inlet temperature in summer. For winter mode, it increases with the decrease of mechanical load and inlet temperature. In addition, the larger the advection velocity of groundwater, the more heat (cold) can be taken away from the pile, and thus the smaller the displacement changes. For the soil types and stratification, the pile head displacement in soft clay is the largest, followed by silty clay and hard clay, and the rock soil is the smallest. Moreover, the soil stratification and cooling and heating cycle operation has a significant effect on the displacement changes of energy piles and should be considered in the design of energy piles.

Quartz grain characteristics of the late Pleistocene hard clay in the Yangtze River delta and implications for sedimentary environment and provenance

AbstractThe sedimentologic fingerprinting in detrital deposit is vital to reconstruct sedimentary environments and discriminate sources. In this study, grain size and microtextural characteristics of quartz from the late Pleistocene hard clay in the Yangtze River delta (YRD) were analyzed by using a laser particle size analyzer and a scanning electron microscope. Subaqueous quartz from the Yangtze River and Yellow River sediments and eolian quartz from the Chinese Loess Plateau loess were also analyzed by scanning electron microscopy to obtain the microtextural characteristics. Quartz grains of the hard clay were characterized by poor sorting, fine skew, bimodal grain-size distributions, and numerous eolian microtextures. The comparison of the quartz grain characteristics of the hard clay with these in eolian loess indicated that the hard clay belonged to an eolian deposition. Moreover, the fine quartz grains of the hard clay were dominated by eolian microtextural characteristics, representing long-distance transportation. The coarse quartz grains of the hard clay exhibited more subaqueous microtextural characteristics, which indicated that the coarse fraction of the hard clay was derived from the proximal source regions in the YRD. The determination of buried eolian deposition with multiple sources in the YRD implies a southward westerly jet stream, strengthened eolian dust transportation, and extensive aridification in the YRD due to the increased Northern Hemisphere ice sheets in Marine Oxygen Isotope Stage 2.

Mapping of laterite zones using 2D electrical resistivity tomography survey in parts of Paschim Medinipur, West Bengal, India: An approach for artificial groundwater recharge

Earth’s most valuable and renewable resource ‘groundwater’ is depleting rapidly in the last few decades. Due to lack of proper usage and planning of groundwater leads to water scarcity in some problematic areas of Paschim Medinipur, West Bengal, India. The presence of impervious laterite on the surface as well as in the subsurface is the main problem that hinders the natural groundwater recharge in the area. To overcome this issue, artificial recharge of groundwater and rainwater harvesting can be the best solutions. However, this requires precise information about the subsurface structures. Therefore, 2-dimensional Electrical Resistivity Tomography (ERT) surveys are performed at nine locations (separated by 3–4 km distances) covering a distance of about 30 km along a profile in E–W direction centrally located between Kangsavati (in the north) and Subarnarekha (in the south) rivers. The present study area extended between Village Chirakuti in the west to Village Nandakishorpur in the east, in the Paschim Medinipur district of West Bengal. A principle profile line of 30 km with a station interval of 3–4 km is covered along east–west direction. 2D data is collected at nine locations (with 800 m spread) along the principle profile. Every dataset is interpreted using RES2DINV software. The study reveals that the observed resistivity is highest in the western part (1400 Ωm) and lowest in the eastern part (40 Ωm) of the principle profile. The 2D interpreted resistivity cross-sections reveal that, the western part of the principle profile has conductive layers overlaid by a resistive layer on the top. The eastern part of the principle profile represents flat younger alluvium deposits. Most of these sediments are clayey sand, coarse sand on top and hard clay, small gravels to 10 mm gravels in deeper parts. The water crisis is mainly in the western part. So puncturing the top laterite layers and allowing the runoff water to penetrate into the subsurface may solve the problem. Building watersheds for agriculture in the western part of the principle profile line could help in increasing of the groundwater level in the study area.

Viscoplastic drop impact on thin films

We use high-speed imaging to study the effect of thixotropic aging in drop impact of yield-stress fluids on pre-coated substrates. Our results reveal that drop splashing is suppressed for "aged" compared to "unaged" samples, indicating that thixotropic breakdown timescales during impact are long enough to affect the dynamics. We propose and test several hypotheses for modifying the dimensionless group ${\rm IF}(D/t)$ [1,2] to account for thixotropic aging. The main challenge is that the steady flow properties (Herschel-Bulkley model parameters) used in the current dimensionless group cannot be defined or measured for thixotropically aged samples, because any deformation inherently rejuvenates and breaks down the microstructure. We find the most suitable hypothesis is to only increase the yield stress ($\sigma_{\rm y}$, plastic component) based on the storage modulus of aged samples, while keeping the viscous parameters ($K$ or $\eta_{\infty}$) constant. The work reveals fundamental insight into rarely studied short-timescale flow conditions with thixotropic effects. These results are important for applications such as fire suppression or spray coating that involve complex fluids of varying degrees of thixotropic aging.

Дослідження віброударного способу заглиблення паль

Палі для будівництва фундаментів використовувалися ще в далекій давнині. Спочатку палі використовувались при ущільненні ґрунтів з метою значного підвищення несучої здатності основ фундаментів, а потім – в якості несучих елементів, які можуть передавати навантаження від плити фундаментів на ґрунт. Палі спочатку виготовляли із лісоматеріалів і забивали ручними молотами. Голови паль зрізали нижче рівня води, захищаючи, тим самим, їх від дотикання із повітрям. В даний час в фундаментобудуванні використовується більш ніж 100 типів паль, які класифікуються по трьома найбільш суттєвими признаками: це по особливістю передачі навантаження на ґрунт (палі-стійки, висячі, ущільнення, тертя); – по способу заглиблення або вбудуванні палі в ґрунт (що виготовляються раніше і заглиблюються в готовому вигляді; виготовлені в проектному положенні; комбіновані); – по матеріалу: дерев’яні, бетонні, залізобетонні, комбіновані.По особливостям передачі навантаження на ґрунт найбільше розповсюджені палі -стійки і висячі палі. Палі-стійки передають навантаження на ґрунти в основному нижнім кінцем на малостиснутих ґрунтах (скалисті, пісчані, тверді глини). Висячі палі передають навантаження на любі ґрунти нижнім кінцем , а також за рахунок сил тертя по боковій поверхні.З кожним роком все більше набуває використання віброударного обладнання, так названих вібромолотів. Ця техніка успішно використовується при спорудженні надійних фундаментів під різні споруди.Здійснення сказаного вимагає вивчення і дослідження процесу віброударного заглиблення паль. а також створення найбільш продуктивних способів його виконання.Одним із перспективних напрямків є впровадження фундаментів із паль при будівництві споруд при щільній забудові в містах і селищах.Також необхідно відмітити, що спорудження фундаментів із паль дає можливість впроваджувати комплексну механізацію і автоматизацію технологічних процесів, що значно підвищує продуктивність робіт.Віброударне заглиблення паль є одним із найбільш продуктивних способів побудови надійного фундаменту під різні споруди . Віброударне заглиблення, котре широко впроваджується на будівництві , належить до ударної технології заглиблення паль. Метод віброударного заглиблення паль полягає в тому, що при вібрації суттєво зменшуються сили виникаючого тертя і сили зчеплення між палею і ґрунтом, а в результаті значно зменшуються сили опору заглибленню палі.В даний час, при проектуванні вібромолотів динамічні фактори при їх експлуатації не враховуються. Тому надійність можна підвищити, якщо на стадії їх проектування враховувати хвильовий характер навантажень віброударної техніки.Віброударне заглиблення паль нами розглядалося у взаємодії механічних і електромагнітних процесів і в результаті була отримана математична модель динамічних процесів при роботі вібромолота, котра включала нелінійні диференціальні рівняння руху мас вібромолота і лінійне диференціальне рівняння електромагнітних явищ в двигуні приводу.Аналізуючи отриману інформацію можна акцентувати, що віброударному методу заглиблення паль мало приділено уваги і широка інформація практично відсутня. Тому являється актуальним створення продуктивних зразків вібромолотів, методик їх розрахунків і проведення наукових досліджень динаміки робочих процесів цих машин на що і направлена дана магістерська робота.В даній роботі нами теоретично досліджено, з використанням математичного застосунку MathCAD, динаміку вібромолота і отримано результати котрі можуть бути використані при проектуванні та визначенні динамічних навантажень подібних віброударних машин.При розрахунку вібромолотів на статичну й утомленуміцність коливальні процеси конструкцій та їх динамічні навантаження, в цей час, не враховуються. Однак їх несучу здатність можна значно підвищити, якщо у розрахунках при їх проектуванні враховувати їхні амплітудно-частотні характеристики. Відсутність ж уточненої методики розрахунку сучасних вібраційних машин, в тому числі і вібромолотів, для здійснення ефективного занурення різноманітних паль ускладнює їхнє проектування і експлуатацію.Метою статті є висвітлення результатів математичного моделювання коливальних процесів при заглибленні паль вібромолотом та визначення динамічних навантажень на його елементи.В роботі теоретично досліджено, з використанням математичного програмного середовища MathCAD, динаміку механізму привода вібромолота і отримано результати які можуть бути використані при проектуванні, розрахунку та визначенні динамічних навантажень подібних вібраційних машин.

Estimation of aquifer parameters using pumping tests: case study of hotel Makassar paradise

The purpose of this study was to determine the aquifer parameters and the condition of groundwater in the study location, namely the continuity coefficient (Transmissivity, T), water retention (Storativity, S) and permeability coefficient (Hydraulic Conductivity, K). This aquifer parameter is very necessary, especially in the project to be excavated for basement construction, where the high groundwater is one of the problems that must be overcome when the excavation of the soil. This pumping test was carried out by making 10 investigation well points, namely 1 point of the pump well (TW) and 9 points of observation well (OW1-OW9). Thus the pump well (TW) is installed to a depth of 20 m, the end is 2 meters into the hard consistency clay layer. While 9 points of observation well (OW1 - OW9) were installed to a depth of 15 m, so that all the pipes were in a layer of the fine sand relative density of moderate just above the very stiff consistency clay layer. Based on calculations with the Theis method obtained: a) The cross-section A-A has a value of Transmissivity (T) ranging between 124.27 - 966.58 m2/day, Hydraulic Conductivity (K) ranges between 0.012 - 0.094 cm/s, Storativity (S) ranges between 0.084 - 0.472. b) The cross-section B-B has a value of Transmissivity (T) ranging between 230.14 - 621.37 m2/day, Hydraulic Conductivity (K) ranges between 0.022 - 0.060 cm/s, Storativity (S) ranges between 0.125 - 0.416.

Performing application of cooper-jacob method for identification of storativity

Transmissivity is estimated by fitting a straight line between time versus drawdown on semi-logarithmic paper. The test data of both confined and unconfined aquifers were analyzed by many practitioners that are used cooper-Jacob method to estimate the drawdown equation, regardless of the differences between theoretical and practical conditions. The other parameter is storativity overestimated, so the aim of this research is to analyze ten pumping test data located in Makassar area by using cooper-Jacob’s (1946) time drawdown approximation of Theis method to estimate the aquifer parameters, also in order to determine the reasons which are affecting the reliability of the storativity value and obtain the important aspect behind that in practice. The pump well is installed to a depth of 20 m, the end is 2 meters into the hard consistency clay layer. The radius of the pump well used in a single well test to estimate the storativity value of the type of aquifer layer unconfined with the Cooper-Jacob method gives excessive value, but if the radius of the pump well is used larger by inserting the radius of the gravel filter layer is obtained a significant value that approaches the storativity value that has been estimated by Theis method uses one pump well and nine observation wells.

An Evaluation of Pile-Raft Interaction in Cohesive Soils using 3D Finite Element Method

This paper presents the results of a numerical study of soil-structure interaction in a piled-raft foundation system in clay soil by reviewing the deformation and load transfer mechanism of the piled-raft foundation system. ABAQUS was used to evaluate the interaction in the system, while a Mohr-Coulomb constitutive model was chosen to model the clay soil. Verification of the model was conducted by comparing the simulation result to an experimental laboratory result. The verification result showed that the model used in this research agreed well with the experimental laboratory research. Subsequently, a parametric study was performed by varying the pile spacing, raft size, pile length, and raft thickness. A parametric study was conducted on very stiff and hard clays. This study concludes that the load transfer mechanism in a piled-raft foundation system between the pile and raft foundation occurs after the pile reaches its ultimate capacity and is in the plastic zone.

Analysis of the statistical variables related to the service in high performance male tennis in junior and absolute category

The aim of the study was to show the differences in the game statistics related to the service in professional and junior category in three surfaces and to determine statistical differences during the game regarding both categories. A total of 269 individual Grand Slam tennis matches (Australian Open, Wimbledon and Roland Garros) were selected on three different surfaces (hard court, grass and clay). The data was collected from the official websites of the tournaments. A total of 10 variables were analyzed in professional category and 7 in junior. Absolute players obtained higher values (p <0.05) of aces, aces per set, percentage of 1st Services and points won with 1st and 2nd Service and committed fewer double faults per set than juniors in all surfaces. It is concluded that the increase in performance in the variables related to the service plays a decisive role in order to achieve a professional status.

SEA-LEVEL RELATED ENGINEERING GEOLOGY AND INTRINSIC COMPRESSION BEHAVIOUR OF BANGKOK CLAYS

All the important infrastructures in Bangkok city are founded in soft, stiff to hard clay layers up to 80 m deep. The engineering properties of these clays depend a lot on their microstructure, which in turns is a result of geological conditions governing the deposition and subsequent geological processes of loading, unloading and weathering. Thus, a study of soil microstructure would help understand better the soil engineering properties to be used in geotechnical analyses. In this paper, a detailed review of sea level-related engineering geology of the depositional environment of Bangkok clays was made. Geotechnical boreholes were drilled at six testing sites as part of a groundwater recovery study project, from which samples of Bangkok clays were collected up to 80 m deep and tested. Based on the results of an integrated geological-geotechnical analysis the microstructure of Bangkok clays was indirectly investigated via their intrinsic compression behavior and in-situ state. It was found that the Soft Bangkok clay at depth 4-11m (SOCL) is a bonding-dominated or cemented clay with a meta-stable structure, whereas stiff clay at depth 12-24m (STCL), the first hard clay at depth 30-50 m (HCL01) and the second hard clay at 50-80 m (HCL02) are fabric dominated with a stable structure. On the plots of void index versus depth the in-situ state the Bangkok soft clay lie in the sedimentation compression range, the stiff clay and the first hard clay lie both in sedimentation compression and overconsolidated clay ranges, while the second deeper hard clay (HCL02) lies only in the overconsolidated clay range.

SETTLEMENT BEHAVIOR OF ROAD SURFACES CAUSED BY DISSOLUTION OF SALT LAYERS

This research was aimed at studying the settlement behavior of road surfaces caused by the dissolution of salt layers that in turn create cavities. The dissolution can happen naturally or occur from salt mining. The proposed project’s site was Highway 2229 from km 4+066 to km 4+275, Kud Ruakham Sub-district, Ban Muang District, Sakonnakhon Province. The 2015 soil layer drilling survey revealed layers of hard clay and compact soil or shale with low plasticity. Cavities were found at the depth of 42 meters over sand stone layers. The analysis of road surface settlement was based on the Empirical Method and theories of Peck1969)), O’Reilly and New1982)), and Rankin1969))to determine the i and Vs parameters based on Smsx from the surveys of road surface settlement from 2013 to 2018. Using the survey results, the analysis by the theory of O’Reilly and New1982)) showed i at 21 m and Vs ranging from83.24%to85.14%of Vs. The analysis based on the survey data and Rankin’s theory 1969)) showed i equal to 19.16m and Vs between 91.23%%and 93.32%of Vs. The analysis of the surveyed data showed the end of surface settlement in 2016, which was consistent with the drilling survey in 2017 from which no cavities were found on the sand stone layers.

Experimental microscopic investigation of the cyclic swelling and shrinkage of a natural hard clay

In this paper, a microscopic experimental investigation of the swelling–shrinkage behaviour of a hard clay subjected to wetting and drying (W–D) cycles is presented. Three W–D cycles with a range of relative humidity from 20 to 98% were performed on the hard clay sample through varying the temperature and the vapour pressure in an environmental scanning electron microscope (ESEM). The obtained ESEM images of the material at different hydric stages were analysed using a digital image correlation method, and full-field strains at the micrometre scale were quantified. The results show that the deformation of the material when subjected to W–D cycles is significantly heterogeneous and it is closely related to its microstructure. The different contributions of clay particles and of inclusions to swelling and shrinkage of the hard clay are revealed: the clay minerals swell, which is, however, constrained by the no-swelling inclusions; the interaction between the different phases is significant. A residual swelling is found at the end of the first W–D cycle. The residual swelling continues to accumulate during the second cycle but becomes stable for the third cycle. Further microstructural analysis shows that the irreversible swelling can be mainly attributed to the appearance and propagation of microcracks accompanied by a limited unrecoverable deformation of the clay minerals.

Characterization and Application of Catalysts Hard Green Clay and MoO<sub>3</sub>/ Hard Green Clay in Transesterification Reaction of Soybean Oil

The present study describes the preparation of catalyst MoO3 supported on smectite clay by the solution impregnation method and its evaluation as a heterogeneous catalyst in the production of biodiesel from soybean oil. The individual effects of catalyst (hard green clay and MoO3/hard green clay) on kinematic viscosity of produced biodiesel and conversion were investigated. The samples were characterized by X-ray diffraction, X-ray fluorescence spectroscopy and N2 adsorption-desorption. Conditions of soybean oil transesterification were: 5% catalyst by weight, 1:12 oil to methanol molar ratio, at 200 oC for 60 minutes. Patterns of X-ray diffraction showed the characteristic peaks of the structure of smectite. The results of X-ray diffraction suggests that MoO3 species exist as highly dispersed surface species. Molybdenum metal identified as effective catalysts for the transesterification reaction of soybean oil with methanol. A preliminary design assessment show that this catalysts (MoO3/HGC) is sufficiently active achieving conversion in excess of 62,07% at temperature below 200 oC.

Lithium mining: Accelerating the transition to sustainable energy

In the actual context of climate change threats, lithium batteries fulfil lot of expectations in order to achieve a cleaner and more sustainable solution for transports, embodied by electric vehicles. According to different studies that identified a noticeable discrepancy between consumption and production, undersupply should be expected until 2045 in the European Union. Thus, ensuring lithium supply for the growth of energy-sustainable industrialised countries is crucial, and different approaches should be undertaken as for the purpose of technological transition, time matters.This paper focuses in analysing lithium prices and their expected evolution. It also studies in deep five ready-to-go lithium mining investment projects worldwide: Whabouchi Project in Canada, Keliber Project in Finland, Cauchari-Olaroz Salars Project in Argentina, Sonora Project in Mexico, and Pilgangoora Project in Australia. The main purpose being to provide an exhaustive analysis of lithium mining investment in order to facilitate the development of preliminary economic assessments of future mining projects, fighting again supply disruption and accelerating the transition to sustainable energy. Conclusionsstate in first place that prices are expected to return to a more stable behaviour, mainly based on a ramping up of the production by miners, as there are sufficient lithium recoverable resources in order to ensure the demand of future electric vehicles. Moreover, recycling of lithium batteries will represent a significant supply for the future.In second place, an order of magnitude both technical and economic of this mining industry is given. Two aspects can be highlighted: (1) it was possible to establish a linear correlation between the capital expense of the lithium mining investment projects and their expected production of lithium carbonate; and (2) continental brine deposits, where the extraction of lithium is conducted by evaporation processes in man-made ponds, will not represent a push out of the market for the lithium extracted from hard rocks and clays using conventional mining methods as they have almost the same operating costs.

Attenuation study of a clay-rich dense zone in fractured carbonate reservoirs

Seismic attenuation in clay-rich dense zones remains unknown, despite the importance of such zones in hydrocarbon reservoirs, where they delimit the reservoir zones and isolate them from nearby aquifers. We have determined that a dense zone separating two carbonate reservoirs of an onshore oilfield in Abu Dhabi, United Arab Emirates, exhibits the highest intrinsic attenuation even though the zone contains no hydrocarbons. The frictional movement due to the elastic contrast between the hard carbonates and soft clay is most likely the dominant mechanism in the dense zone. The compressional sonic and vertical seismic profile (VSP) attenuation are on the same order of magnitude and are both maximum in the dense zone. Therefore, it is possible that the same attenuation mechanism in this zone exists at low and high frequencies; whereas the intrinsic attenuation mechanism in the reservoir zones, which are more permeable and porous than the dense zone, can be explained by the coexistence of global and squirt-flow mechanisms. Moreover, sonic attenuation exhibits higher magnitudes than VSP attenuation in these zones. This is due to the fact that the squirt-flow mechanism, which can take place between pores and fractures, is more important at sonic frequencies. The scattering mechanism is also important in the reservoir zones; this is due to the high heterogeneity and the presence of fractures in these zones.