Fresh Clay Research Articles

Interface Shear Strength Progressive between Weathered and Fresh Clay Shales

Interface Shear Strength Progressive between Weathered and Fresh Clay Shales

Replacement of Weathered Clay Shale Using Soil Cement for Bridge Approach Embankment in Purwakarta - Indonesia

Clay shale is a sensitive soil material that easily experiences weathering if exposed to open air, sunlight, water. Weathered clay shale is commonly located near the surface and has a soft consistency due to surface water infiltration. Referring to this condition, weathered clay shale is prone to experience soil movement if backfill work is conducted on the top side of weathered clay shale material. Therefore, to minimize the potential of soil movement during backfilling, soil replacement using soil cement is recommended to be conducted to gain higher soil shear strength and to prevent excessive water infiltration to the fresh clay shale. To gain further understanding, a comprehensive study about the replacement of weathered clay shale using soil cement for bridge approach embankment in Purwakarta was carried out. This study comprises site observation, field data collection, laboratory test, explanation about implementation and quality control. The stages in implementation of soil cement is carried out in several stages such as : evaluation of soil condition on the project site, checking the suitability of local soil for the soil cement stabilization, conducting field test trial mockup followed by quality control, conducting crumb test and mechanical properties test for soil cement mixture. Based on assessment results, the soil cement mixture shall be directly compacted after the soil cement mixture is homogeneous to prevent segregation and shall be given a curing time of at least 3-7 days without additional water to gain better soil shear strength. Furthermore, according to the crumb test result, soil cement material was identified as quite impermeable which is verified by evidence that there was no significant change in water content and the soil cement sample could still stand firm after soaked for 7 days.

Breathing Room: Working Principles of Independent Art Spaces in African Cities

Breathing Room: Working Principles of Independent Art Spaces in African Cities

Scaffold-free 3D printing of shells: Introduction to patching grammar

This paper describes the Patching technique for building shells without wasteful support, thanks to 3D Printing technology. The method developed in this paper extends ancient vaulting techniques and decodes and formalises them into a design Grammar. Furthermore, numerical tools such as mesh pattern topology and shape topological skeleton are used to adapt vaulting techniques to 3D Printing data. This Grammar classifies the self-standing interconnected components (Patches) and automatically decomposes the non-traditional shapes into those Patches following the Patching process. As a result, the practitioners can use the Patching technique to fabricate low-cost, efficient shells. The presented prototype demonstrates that the Patching technique can contribute to printing shells with low-strength material such as fresh clay without any scaffolding. However, more research needs to be done on the material design and rheology control, shells' cross-section optimisation, and material failure theories such as Mohr-Coulomb and their application to 3D Printing using earth-based material.

X-ray diffraction studies of onshore mud volcanoes in parts of the Upper Benue Trough, northeastern Nigeria

The mineralogical studies of clay from the onshore mud volcanoes discovered in parts of the Upper Benue Trough of Nigeria provide a clue about the geological formation from which the extruded mud originates. The study area is a part of the Cretaceous Upper Benue Trough filled with Early Cretaceous continental deposits and Late Cretaceous marine deposits, having a history of magmatism dating from the Albian to the Pleistocene. The study approach involves integrated inorganic geochemical analysis of the samples to reveal their composition and origin. The results of XRD analysis of the fresh clays from the mud volcano revealed the presence of quartz, kaolinite, and other clay minerals (illite-smectite), feldspars, and in much lower quantities, other accessory minerals including muscovite, evaporites, calcite and dolomite, trona, barite, goethite. The saprolite samples are composed mainly of quartz, kaolinite, smectite-illite associations, and feldspars, traces of goethite, calcite, and evaporate minerals (sylvite, halite). The presence of calcite, dolomite, sylvite, and halite suggests the marine origin of the rocks, while trona mineral is a non-marine evaporate. The coexistence of these minerals in some of the analyzed samples suggests the deposition of sediments in a transitional environment of deposition. Traces of marine minerals are present in some of the samples but completely absent in others collected from another site. This suggests that the source rock formations from which the material originated are within the Upper Bima Sandstone interpreted as being deposited in a non-marine environment or the Yolde Formation, which is known as a transitional unit (transitional between the outcropping continental Upper Bima Sandstone and marine Pindiga Formation).

Micromorphological features of soils of semidesertic solonetzic complexes under different herbaceous communities with the participation of fodder plant Kochia prostrata (Caspian lowland)

The aim of the study was to research the relationship of chemical and micromorphological properties of soils with the growth ofKochia prostrata. The objects of study were the soils on natural pastures of the North-Western part of the Caspian lowland. It was laid 4 soil pits (soils – light solonetz, solonetzic chestnut) with the maximum penetration depth of the main mass of roots of the studied plants.K. prostratais a very plastic forage species that can grow on soils with a wide range of morphological properties, different salt content and their chemical composition. It is revealed that on the background of almost the same content of humus and high content of exchangeable magnesium micromorphological features represent the different degree of manifestation of primary pedogenic processes – humus accumulation, leaching of soluble salts, gypsum accumulation, carbonate enrichment, solonetzization. Despite the different content of exchangeable sodium, in all soils there are fresh clay or humus-clay illuvial coatings, indicating the manifestation of the modern eluvial-illuvial redistribution of fine matter (lessivage or illimerization).

Use of ceramic waste powder for manufacturing durable and eco-friendly bricks

In present work, Ceramic Wastes Powder (CWP) is recycled as partial replacement of fresh clay in bricks. The proportions of replacement were fixed as 4, 8, 12, and 16% by mass of clay. Total 250 specimens were manufactured, having 50 bricks of each category. Physical, chemical and mechanical characteristics were determined and compared with those of control specimens. The analyzed characteristics included unit weight, efflorescence, apparent porosity, water absorption, pore size distribution, chemical composition, crystalline phases, micro-structure, compressive & flexural strengths, resistance towards freezing & thawing and the sulfate attack resistance. It was concluded that the bricks incorporating CWP exhibit improved mechanical strength, higher resistance to efflorescence, freeze/thaw and sulfate attack, lower porosity, and dense micro-structure. The ultrasonic pulse velocity test also confirms that the inclusion of CWP enhances the brick quality. In addition, the incorporation of CWP increases the unit weight, making bricks suitable for heavy duty and commercial structures. The study reveals that highly durable bricks can be manufactured using CWP.

The Influence of Al<sub>2</sub>O<sub>3</sub> Microparticles on the Pore Structure of Fired Clay

Contemporary demand after high-quality ceramics leads to the depletion of raw material deposits. The industry also produces waste secondary materials that cannot be used directly for the desired purposes. It is therefore necessary to find other uses for these materials. It is common practice in the ceramics industry to stockpile fine fractions of refractory clays prior to their firing in a shaft kiln. These fractions have the size of 35 mm and less and when stored in a mound are facing a risk of weathering. Finding a purpose for these unused materials will markedly slow down fresh clay mining and make the production more eco-friendly and cost-effective. This paper seeks a suitable technology of treating fine fractions of BC (Brezina Clay), sometimes called FBC (Fine Brezina Clay), prior to its being fired into grog. The stockpiles hold tens of thousands of tons of these fractions. The properties of the fired clay are determined by the length of time for which the material has been stockpiled, moisture content, of the clay, as well as the briquetting pressure before firing in a shaft kiln. FBC contains approx. 41 % of aluminium oxide. This amount is not high enough for certain applications. The aluminium oxide content can be increased by the addition of bauxite, corundum, mullite, kaolin, clays rich in Al2O3, or technical Al2O3. The experiment described in this paper tested how the addition of technical Al2O3 affects the pore structure of fired FBC, which is later used as a grog in both shaped and non-shaped refractory products. The influence of firing temperature on the material's mineralogy was examined as well

Plant Design for Regeneration of Spent Bleaching Clay by Boil-Off Method and Acid Treatment

There are significant economic and environmental benefits to the recycling of the waste generated by edible oil refineries, spent bleaching clay is one of the major ones. These spent bleaching clays are disposed into landfills which causes environmental pollution in addition to odors and fire hazards. The amount of fresh clay used in edible oil refineries in Saudi Arabia is estimated to be 6000 tons per year. Thus, boil-off method followed by acid activation is explored in this paper as a chemical recycling method for spent bleaching clay. This treatment can remove the adsorbed oil content and reactivate the clay to recover the bleaching ability where it can be sold again with a reasonable price. The proposed process handles a feed of 26 tons per day of spent bleaching clay, the suggested design achieves a deoiled and activated clay with bleaching ability as fresh one. The plant includes batch reactors to carry out the oil removal by boil-off method then followed by acid activation. After both reactors, filter presses combined with washing process to separate the filtrate and neutralize the products. Heat exchangers, dryers and storage equipment are also included in the design. The suggested design requires a capital investment of $2.079 MM and the cash flows of this plant suggests that it will break even by around 5.2 years.

Evaluation of sustainable clay bricks incorporating Brick Kiln Dust

Bricks are extensively used building material all over the world owing to their low price, frequent availability, and ease of handling. However, as a matter of fact, they also consume a huge quantity of good quality clay. In this research, Brick Kiln Dust (BKD) was used as partial replacement of fresh clay in bricks. The replacement percentages were kept as 0%, 5%, 10%, 15%, 20% and 25% by mass of fresh clay. In total 300 brick samples were prepared. The bricks prepared by incorporating the waste materials were analyzed for their physical, chemical and mechanical properties and the results were compared with those obtained from the control samples. The brick specimen were evaluated for their unit weight, water absorption, apparent porosity, efflorescence, pore size distribution, micro structure, crystalline phases, chemical composition, compressive and flexural strength, and sulfate attack resistance. The results indicate that the inclusion of BKD marginally reduces the mechanical strength, increases water absorption capacity, results in lower unit weight and higher resistance to efflorescence and are useful for insulation owing to high porosity. The research concludes that the BKD may be incorporated in the production of clayey bricks, saving as much as 25% of fertile clay, which is environmentally very beneficial.

The foraminiferal biostratigraphy and paleoenvironmental interpretation of the Gault Clay Formation (Middle and Upper Albian) at Munday's Hill Quarry, Bedfordshire, UK

The foraminifera of the Gault Clay Formation, exposed in the Munday's Hill Quarry (Leighton Buzzard, Bedfordshire, UK), are described. This quarry, which is worked for the underlying Woburn Sands, is periodically 'refreshed' and the Gault Clay overburden removed. This cleaning of the quarry was undertaken in 2018 and provided access to a fresh clay succession. An 11.4 m section of the Gault Clay Formation was logged and samples collected for micropaleontological analysis, ranging from the Hoplites spathi Subzone to the Hysteroceras varicosum Subzone. A total of 58 specieswere identified from a total of 11,345 foraminifera examined in 20 samples. Two distinctive assemblages are evident; the Lower Gault Clay contains abundant aragonitic foraminifera, while the Upper Gault Clay is dominated by agglutinated foraminifera. This distribution is repeatedly recorded across South-Eastern England and is likely due to ecological constraints such aswater depth, but taphonomic processes cannot be dismissed. The succession at Munday's Hill Quarry is compared to comparable successions in East Anglia, Sussex (Glyndebourne Borehole) and Kent (Copt Point, Folkestone).

Physical, mineralogical and mechanical characterization of ready-mixed clay plaster

The use of clay plasters with or without plant fibers (straw, hemp or other) inside buildings is currently showing considerable growth in many countries. Despite this development, there are very few data in the literature on the characteristics of clay plasters. This paper deals with the characterization of five ready-mixed clay plasters from French brickworks using the recent German standard. The work essentially consisted in measuring the flow of fresh clay plasters and their characteristics after hardening (shrinkage, and compressive, flexural and adhesive strength). The characterization of the samples showed that the granular characteristics were practically the same and that the main difference concerned the nature of the clayey minerals they contained: four samples were essentially composed of montmorillonite, chlorite and illite whereas one was only composed of kaolinite. Despite this difference, the flow of fresh clay plasters and their characteristics after hardening (shrinkage, compressive and flexural strength) were very similar and were comparable to the values given by the standard. However, the measurement of the adhesive strength led to two significant problems: the dispersion of the values was very high and the results were markedly different from the values given by the standard. For these reasons, it seems necessary to complete and adapt the procedure for measuring adhesive strength and it could be interesting to develop new tests for the measurement of this important characteristic, either in the laboratory or on building sites.

Assemblage structure and use of anthropogenic roosts by bats in the Eastern Carpathians: Case study in the Bieszczady National Park (SE Poland)

In relation to almost completely reduced anthropogenic pressure after 1944 and the consequently low number of present settlements, impoverishment of the bat (Mammalia: Chiroptera) fauna has been suggested for the Western Bieszczady Mountains (Mts), southeast Poland. During a field study in 2009–2011, we recorded 15 bat species within the Bieszczady National Park and 19 in total (i.e. all but one or two expected for the Bieszczady Mts), including a locality at a cave near the park border. At 26 (72%) of 36 localities sampled over water, forest roads and glades, in 278 mist net hours, we captured 159 bats representing 12 species. Species most frequently sampled and most abundant in captures were Myotis brandtii and M. daubentonii (both over 50% of localities and 80% of bats in total). Most of the captured bats were males (73%) and adult individuals (85%). Fifty percent of M. daubentonii (both sexes) and several males of M. brandtii, netted over streams, were soiled with fresh clay, indicating day roosts of these bats were likely located in rocky crevices at river banks. We found bats (six species) or their faeces in 28 (48%) of 58 inspected roosts in buildings. Vespertilio murinus was the most abundant and most frequent species. The same number of species (five) used farm buildings and houses. Most bats found at roosts were adult males either solitary or in two colonies of V. murinus. Despite the high number of species recorded, we confirmed the impoverishment of the attic dwelling species set. Although no church attics, frequently utilized by colonies of Rhinolophus hipposideros and M. myotis in the other Carpathian regions, are present in the Bieszczady National Park, local buildings as a limited source of roosting site are important for bat conservation.

Evaluation of short-term stability for sea-wall structure at Kobe Airport

Prior to the huge reclamation work for constructing Kobe Airport, the sea-wall structure resting on a 30m-thick soft Holocene clay layer in the 16m-deep sea was constructed at stages over the period of three years. Regarding the design of short-term stability of the sea-wall structure, the ratio of undrained shear strength of the normally-consolidated seabed clay to in-situ yield stress was estimated to take the value of 0.35 in order to satisfy the factor of safety in excess of 1.3. This design strength in the clay foundation was checked with the unconfined compression strength of the fresh clay samples retrieved from boreholes during the construction. In this paper, the short-term stability of the embankment in this well-documented case history was re-evaluated after-the-event with the results of comprehensive series of constant-volume direct shear box tests in which the effects of strength anisotropy as well as the shearing rate on undrained shear strength were both examined. Discussion is made how to estimate the short-term stability of the embankment by considering the effects of strength anisotropy and shearing speed on undrained shear strength and how it is linked with the current design method in Japan in which a half of the undrained compression from unconfined compression test is employed.

EFFECT OF CLAYS AND ADSORBENTS ON THE NITROGEN CONTENT AND THE STABILITY OF JET FUELS

The effect of composition, surface area and pH of different clays and alumina adsorbents on the stability of jet fuel was studied. The stability of jet fuel was tested following the ASTMD 3241 procedure. Under the batch adsorption conditions, clays and adsorbents were not effective in adsorbing polar molecules and improving the stability of jet fuels. Under the column adsorption conditions, the effectiveness of clays and adsorbents in improving the stability of jet fuel was found to vary. Clays having a high surface area and an acidic pH were found to be more effective in adsorbing polar molecules and improving the stability of jet fuel. High surface area alumina adsorbents were found effective in adsorbing basic nitrogen molecules and improving the stability of jet fuel despite having a basic pH. The basic type nitrogen compounds, pyridines and quinolines, were found to affect the stability of jet fuel. The initial effluent jet fuel passed through fresh clays was found to have no N compounds and a good stability. However, the analysis of effluent jet fuel showed a gradual increase in N content reaching the level of N content in untreated jet fuel. The effluent jet fuel reaching 9–10 ppm of N content failed the stability test indicating that clays need to adsorb and retain N compounds. The adsorbent capacity of different clays was studied but no significant difference in retaining N molecules was observed.

Oil removal from spent bleaching clay by solvent extraction

Solvents screening experiments using a Soxhelt extractor were conducted to determine the best solvents for oil removal from spent bleaching clay. The solvents extracted oil in the following decreasing amount: methylethylketone > benzene‐ethanol mixture (1:1 by volume) > acetone > trichloroethylene = dichloromethane > chloroform > petroleum ether > benzene > n‐hexane > methanol. Four of the safest solvents, methylethylketone, acetone, petroleum ether and n‐Hexane were selected for further studies. Large scale treatment of spent clay with the selected solvents were conducted in a batch stirred reactor. The effect of solvent type, solvent to clay ratio (SCR), time of extraction and extent of mixing on the percentage of oil extracted (POE) were investigated. The corresponding optimum conditions for the four solvents were: extraction time time = 5 minutes, solvent to clay ratio = 4 to 5, extraction temperature = 25 °C (room temperature) and mixing rate = 150 to 200 RPM. The bleaching efficiency (compaerd to to fresh clay) of the clay deoiled by methylethylketone, acetone, petroleum ether and n‐hexane were 77%, 65%, 51% and 27%, respectively.

Newly Discovered Equilibrium Controls HF Stoichiometry

Abstract The standard description of HF acidizing chemistry suggests a stoichiometry that has been found to be deficient. This paper describes the discovery of a chemical equilibrium between silicon fluorides, aluminum fluorides, and HCl that controls the "reactivity ratios" or stoichiometry of the primary and secondary reactions of HF acid. The significance of the discovery is that it allows accurate predictions of effluent compositions in laboratory flow tests. This discovery is also consistent with returns analyses from HF treatments recently reported in the literature. The discovery and determination of the equilibrium expression was made possible as the result of recently applied experimental techniques including 19F NMR spectroscopy and fractional porevolume flow experiments. An accurate description of the stoichiometry of the HFacidizing process is presented and verified with laboratory flow experiments and batch tests. Introduction The acidizing monograph indicated that the primary reaction of HF acid onalumino-silicates results in fluosilicic acid (H2SiF6) and complex aluminumfluoride species. Other works suggested the formation of free aluminum (Al3+), aluminum fluoride (AlF3), and fluoaluminic acid (H3AlF6) as reaction products. The ratio of fluoride to silicon and aluminum in the reaction products defines the reaction ratios or stoichiometry. As work continued in HF acidizing, various assumptions were made concerning the reaction products at the end of both the primary and secondary reactions. Work by Hall indicated that aluminumfluorides were still very reactive but could be used to provide a retarded HF system. Based on this information, it was concluded that H3AlF6 was not a reasonable reaction product at all. Later, Gdanski and Peavy reported their results from analyzing HF acid returns and found a composition that (1) was inconsistent with our industry'sclassical thinking about HF and (2) could not be supported by the geochemical simulators of that time. In this particular composition, the silicon fluorides were completely reacted, as well as all of the HCl. In their place was a large amount of aluminum and a large amount of sodium. A secondary reaction was proposed, which assumed a final reaction product of AlF2+ and was written showing the reaction as occurring directly between H2SiF6 and the alumino-silicates. This proposed reaction provided reasonably good agreement for a number of the acid returns analyses performed over the following years. Work recently published by Shuch art and Buster has revealed additional information regarding the true chemical species involved in HF acidizing chemistry. They showed that the dominant silicon fluoride species could best be described as HSiF5. Interestingly, the F/Al ratio during the primary and secondary reactions was dependent on the HCl concentration. With these developments, it became clear that the time had come to perform careful experiments to determine the properly balanced reaction of HF acid through both the primary and secondary reactions. The determination of the stoichiometry through the secondary reaction was particularly important because of recent calculations on fluosilicate precipitation. Equipment and Method Batch Tests. For batch tests, a specified amount of clay was added to a solution of HF or H2SiF6 in a glass container. Some tests were stirred with a magnetic stirring bar while others were left static. Tests were conducted at room temperature, 110 F, or 200 F. Samples of the suspensions were obtained at various time intervals and filtered hot. After the samples had cooled, they were analyzed for their ionic composition. Additional batch tests were conducted as previously described, but at the various time intervals, the entire suspensions were filtered hot, and a small sample was obtained for analysis. A second portion of fresh clay was added to the solution for continued reaction. This process was continued 3 to 6times.

De‐oiling contaminated bleaching clay by high‐pressure extraction

The disposal and re‐use of spent bleaching clay from the vegetable oil processing industry is a problem of growing importance.Although today the only practical way of removal of the spent material is disposal, extraction with organic solvents is a well‐known method of de‐oiling contaminated bleaching clay. In our investigations we compare the extractibility of two different types of bleaching clays with CO2 as a solvent. All experiments were carried out with a high‐pressure extraction plant. The extraction and separation conditions, temperature and pressure, as well as the CO2 mass flow, were varied during experiments. The aim of our investigations was a complete separation of the oil from the adsorbent. The latter should then be re‐used as bleaching clay. The oil and the bleaching clay were analyzed and tested, respectively. The results show that oil of good quality can be recovered and the bleaching clay still has an activity approximately 50% of fresh clay.

The use of Bogdanovich Poldnevitsa clay for a binder

The authors assess the feasibility of Bogdanovich Poldnevitsa clay as an elastic binder for generally brittle refractories. Information on the elasticity, moisture content, microstructure, porosity, and bulk density of the clay is given, as well as its receptivity to pressing and heat treatment processes. Cost benefit analysis revealed that it was more economical to recover the clay from the gaseous waste resulting from its firing than to transport fresh clay to the plant from the outside.

Age-Related Changes in Sebaceous Wax Ester Secretion Rates in Men and Women

Sustainable rates of sebaceous wax ester secretion were measured on the foreheads of 109 men and 167 women, aged 15-97. Each measurement was made after first depleting the cutaneous sebum reservoir by overnight absorption of lipid into a layer of bentonite clay. Lipid was then absorbed for 3 h into fresh clay in which two 2-cm cloth disks were embedded. The absorbed lipid was extracted from the disks with ether and analyzed for wax esters by thin-layer chromatography. For both men and women there was a wide range of wax ester secretion rates at all ages. Rates were highest in the 15- to 35-year-olds and appeared to decline continuously throughout the adult age range. Values of log(wax esters) were better correlated with age than the untransformed values of wax ester secretion. The equations of best fit of log(wax esters) vs age suggested that sebum secretion declines about 23% per decade in men and 32% per decade in women.