Performance of composite foundations with different load transfer platforms and substratum stiffness over silty clay

The semi-rigid pile-supported composite foundation is widely used in highway projects due to its effectiveness in increasing the bearing capacity and stability of foundations.It is crucial to understand the stress distribution across the embankment width and the behaviour of unreinforced foundations.Thus,five centrifuge tests were conducted to examine the bearing and deformation behaviours of NPRS(Non-Connected Piled Raft Systems)and GRPS(GeosyntheticReinforced Pile-Supported systems)with varying substratum stiffness,then a comparative analysis was conducted on embankment settlement,pressures underneath the embankments,and axial forces along the piles.The results indicated that greater substratum stiffness correlates with reduced settlement and deformation at various depths.Deformation occurring 5 meters from the embankment toe includes settlement in NPRS and upward movement in GRPS.The potential sliding surface is primarily located within the embankment in NPRS,whereas it may extend through both the embankment and foundation in GRPS.The pile-soil stress ratio and efficiency in NPRS are higher than in GRPS across the embankment.The axial force borne by end-bearing piles is significantly greater than that by floating piles.As the buried depth increases,the axial force in GRPS initially rises then declines,whereas in NPRS,it remains relatively constant within a certain range before decreasing.This study aids in assessing the applicability of composite foundations in complex railway environments and provides a reference for procedural measures under similar conditions.

Preparation of Clay/Biochar Composite Adsorption Particle and Performance for Ammonia Nitrogen Removal from Aqueous Solution

This study aimed to present a novel clay/biochar composite adsorption particle, which made from abandoned reed straw and clay to remove ammonia nitrogen(NH4^+-N) from micro-contaminated water. The removal performance of NH4^+-N by composite adsorption particle was monitored under different raw material proportions and initial NH4^+-N concentration. Besides, adsorption kinetics and adsorption isotherms were investigated to reveal the adsorption mechanisms. The results showed that NH4^+-N was effectively removed under optimal proportion of biochar, foaming agent and crosslinker with 20%, 3%, and 3%, respectively. The optimal contact time was 150 min and the best removal efficiency was 88.6% at initial NH4^+-N concentration of 20 mg L^-1. The adsorption performance was well described by the second order kinetic model and Freundlich model. The novel clay/biochar composite adsorption particle in this study demonstrated a high potential for NH4^+-N removal from surface water.

Dynamic properties of composite cemented clay

In this work, the dynamic properties of composite cemented clay under a wide range of strains were studied considering the effect of different mixing ratio and the change of confining pressures through dynamic triaxial test. A simple and practical method to estimate the dynamic elastic modulus and damping ratio is proposed in this paper and a related empirical normalized formula is also presented. The results provide useful guidelines for preliminary estimation of cement requirements to improve the dynamic properties of clays.

Adsorption recovery of Ag(Ⅰ) and Au(Ⅲ) from an electronics industry wastewater on a clay mineral composite

The aim of this work is to investigate the ability of an adsorbent of a clay mineral composite to remove and recover gold and silver ions from wastewater.The composite was prepared by mixing phosphogypsum(PG),obtained from an industrial waste,and a natural clay mineral.The materials were characterized before and after use in adsorption by several techniques.Batch adsorption experiments were carried out,and the effects of the contact time and the pH and temperature of solution on the removal processes were investigated.The optimum pH for the adsorption was found to be 4.The adsorption of these metal ions reached equilibrium after 2 h of contact.The pseudo-first-and the pseudo-second-order kinetic models,as well as the Freundlich and the Langmuir isotherm equations,were considered to describe the adsorption results.The maximum adsorbed amount of 85 mg·g^-1 Ag(I)and 108.3 mg·g?1 Au(III)was found.The recovery of the adsorbed gold and silver ions from the adsorbent was also analyzed.Strong acids appeared to be the best desorption agents to recover gold and silver ions.The use of aqua regia gave regeneration rates close to 95.3%and 94.3%for Ag(I)and Au(III),respectively.Finally,the removal of gold and silver ions from an industrial wastewater was tested in batch experiments,and percentage recoveries of 76.5%and 79.9%for Ag(I)and Au(III),respectively,were obtained.To carry out the industrial application of the proposed methodology,an economic viability study is required.

Enhanced Photoactivity of Layered Nanocomposite Materials Containing Rare Earths,Titanium Dioxide and Clay

The nanocomposite materials containing rare earths, titanium dioxide and clay (RE/TiO2/Clay) were characterized and tested for the photocatalytic decomposition of formaldehyde. The results show that nanocomposite materials prepared by doping appropriate rare earth elements have better photocatalytic properties than that prepared by doping excessive rare earth elements. The photocatalytic mechanism of composite materials was studied by integrating the theory of pho-tocatalysis with experiment results. Because the site of photocatalytic reaction was limited in the interspace of clay, photocatalytic reaction occurred by two steps: firstly, organic molecules dispersed into the interlayers of clay; secondly, organic molecules and photocatalyst of RE/TiO2 occurred photocatalytic reaction, resulting in forming carbon dioxide.

Superabsorbent Capability and High Retention Ability of China Clay(Kaolinite)/Polyacrylic Acid Composites for Aqueous Solution

Majority of superabsorbent polymers (SAPs) yet reported either have low gel strength or high production cost. Therefore, we synthesized a novel polyacrylic acid-grafted China clay (Kaolinite) super-absorbent polymer composite (SAPC) with high thermal stability, low cost of production and superior sorption and retention capability for water and salt solution. The resulting SAPCs were extensively characterized and analysed by X-Ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), and scanning electron microscopy (SEM). Results suggested that the composites were thermally stable. Water absorbency increased with increase of clay content up to 45%, while further increase in clay content decreased the water absorbency. Percentage of acrylic acid (AA) and clay by weight shows the optimum absorbency in 35% and 40% respectively. Crosslinker and initiator contents were optimized to be 0.5% and 0.3% by weight respectively. The resulting polymer composite showed high water absorbency of about 785 g/g and 103 g/g of 1% NaCl solution with above 90% retention ability at 50 oC.

Improving the Combined State of Rubber-Clay CompositeInterface by Applying Coupling Agent

The surface modification of clay fines was carried out by using silanecoupling agent. By means of IR spectra etc, a study was made on the combined state ofcoupling agent and clay. A rubber--clay composite material with excellent performancehas been prepared.

Direct Electrochemistry of Myoglobin in DDAB-Clay Composite Films

Ordered films were made by casting a mixture of aqueous dispersions of didodecyldimethylammonium bromide (DDAB)-clay composite and myoglobin (Mb) solution on pyrolytic graphite (PG) electrodes. The Mb-DDAB-clay film electrodes showed stable and reversible cyclic voltammetric responses in buffers and can catalyze the reduction of id (TCA).

Layered Clay-Alginate Composites for the Adsorption of Anionic Dyes: A Biocompatible Solution for Water/Wastewater Treatment

Adsorption properties of layered anionic clay-composites for the removal of anionic dyes from water were studied. The dye adsorption capacities of the composites were higher than the pristine clay. The clay-alginate composite with 5.9% alginate showed highest adsorption for both the dyes. The maximum adsorption capacity of the composite was enhanced by 51% for Acid Green 25 and 160% for Acid Green 27, compared to the pristine layered clay sample. The adsorption isotherm data were fitted to the Langmuir, Freundlich and Temkin isotherm models. The isotherm data could be explained well using the Freundlich isotherm model. Adsorption kinetics was analyzed using normal first order and Lagergren first order kinetic models.

Modeling the Mechanical Properties of Clay Powder Filled Recycled Low Density Polyethylene Composites

This study modeled some mechanical properties of clay powder filled recycled low-density polyethylene, rLDPE (rLDPE composite). The rLDPE is commonly referred to as used sachet water bags. The clay powder (filler) was obtained by sun-drying, grinding, and sieving. Two particle sizes of clay powder were used: −90 μm and −425 μm to represent the passing sizes at different clay powder contents of 5, 10, 15 and 20 wt% which were thoroughly mixed with the recycled low-density polyethylene in an injection molding machine at 173°C. The results showed that the tensile strength, tensile modulus, hardness, flexural strength, fatigue strength and hardness increased with increase in clay powder contents. However, there were decreases in strain-at-breakage and shear strength as clay powder content increased. Model equations showed that smaller particle size enhanced the mechanical properties and equations generated can be used to predict the properties of composites at predetermined clay contents. Standard deviations obtained for the various mechanical properties show that the model, in most cases had the lowest degree of scatter (dispersion) than those of −90 μm and −425 μm. Hence, these models are suitable to predict outcomes of the properties of the clay filled recycled low-density polyethylene composites.

Physical Characterization and Elaboration Discussion of a Clay-PEG 6000 Composite with Natural Clay Matrix

In this paper, we compare different nanoclay-PEG composites and the influence of the input parameters especially the percentage of PEG and the clay size. Because of the facility of material elaboration, dried state with grinding, we adopted a complete experiments plan to obtain a maximum of robustness of the responses. For each sample, we made an XRD analysis to see if we obtain the intercalation of the PEG 6000 (Polyethylene Glycol 6000) within the clay sheets. The characterization adopted consists on the measurement of the shrinking of some cylinders we made, the liquidity and plasticity limits according to the Casagrande protocol used in geotechnical clays characterizations. We utilize also the methylen blue protocol to estimate the variation of the specific surface of ionic exchange of the clay sheets according to the PEG 6000 percentage and the clay sizes. SEM microscopy permits to visualize some of the phases detected by the XRD analysis. The TEM microscopy permits also to see the amorphous phases created by the grinding protocol which affects significantly the specific surface and the shrinking of the new materials. For each section, we made some conclusions with interpretation in order to integrate these results in civil engineering, classical/artisanal material construction and geotechnical fields.

Synthesis and Characterization of a Red Clay Based New Composite Ceramic Material

In this study, a new composite ceramic material using a red clay matrix with different amount of clinker from the cement industry has been developed. The aim is to valorize some natural resources such as red clay and sub-products from the cement industry as clinker in order to develop new materials for industrial and/or catalytic uses. Raw materials were grounded in order to reduce the particle size and obtain a homogeneous slip. The samples were mixed and compressed into pellets and undergo a heat treatment up to 1100℃. Geotechnical characterization has been carried out. Firing proprieties (shrinkage, water absorption, and mechanical resistance to the inflection) were measured. The composition of the ceramic material was investigated by X-ray diffraction, XRF, SEM and EDS methods. The incorporation of clinker in the ceramic composite material up to 50 wt% exhibits good behaviors (physical and mechanical proprieties) and can be used as a ceramic product.

Fracture Toughness Studies of Polypropylene- Clay Nanocomposites and Glass Fibre Reinfoerced Polypropylene Composites

In this paper, a comparative study on the fracture toughness of woven glass fibre reinforced polypropylene, chopped glass fibre reinforced polypropylene and nanoclay filled polypropylene composites is presented. Nanoclays (Cloisite 15A) of 1 wt. % to 5 wt. % were filled in polypropylene (PP) matrix and they were subjected to fracture toughness stu-dies. The specimen with 5 wt. % nanoclay showed 1.75 times and 3 times improvement in critical stress intensity factor (KIC) and strain energy release rate (GIC), respectively, over virgin PP. On the other hand, 3 wt. % nanoclay PP composites showed superior crack containment properties. These structural changes of composite specimens were examined using Transmission Electron Microscopy (TEM) and X-ray diffraction (XRD) methods. It showed that exfoli-ated nanocomposite structures were formed up to 3 wt. % nanoclay, whereas, intercalated nanocomposite structures formed above 3 wt. % nanoclay in the PP matrix. Furthermore, the woven fibre reinforced PP composites demonstrated superior crack resistant properties than that of clay filled nanocomposites and chopped fibre PP composites. However, KIC and GIC values for woven fibre composites were lesser than that of chopped fibre composites. Moreover, KIC and GIC values for both nanoclay filled PP composites and woven fibre composites are comparable even though the clay filled PP demonstrated catastrophic failure. Also, the crack propagation rate of PP-nanoclay composites is comparable to that of chopped fibre composites.

Adsorption characteristics of humic acid-immobilized amine modified polyacrylamide/bentonite composite for cationic dyes in aqueous solutions

Humic acid-immobilized amine modified polyacrylamide/bentonite composite （HA-Am-PAA-B） was prepared and used as an adsorbent for the adsorption of cationic dyes （Malachite Green （MG）, Methylene Blue （MB） and Crystal Violet （CV）） from aqueous solutions. The polyacrylamide/bentonite composite （PAA-B） was prepared by intercalative polymerization of acrylamide with Nabentonite in the presence of N,N＇-methylenebisacrylamide as a crosslinking agent and hexamethylenediammine as propagater. PAA-B was subsequently treated with ethylenediammine to increase its loading capacity for HA. The surface characterizations of the adsorbent were investigated. The adsorbent behaved like a cation exchanger and more than 99.0% removal of dyes was detected at pH range 6.0-8.0. The capacity of HA-Am-PAA-B was found to decrease in the following order： MG〉MB〉CV. The kinetic and isotherm data were interpreted by pseudo-second order rate equation and Freundlich isotherm model, respectively. Experiments were carried out using binary solute systems to assess the competitive adsorption phenomenon. The experimental isotherm data for each binary solute combination of MG, MB and CV were analyzed using Sheindrof-Rebhun-Sheintuch （SRS） （multicomponent Freundlich type） equation.

The influence of freeze-thaw cycles on the granulometric composition of Moscow morainic clay

The freeze-thaw cycling process considerably changes the composition, structure, and properties of soils. Since the grain size is the most important factor in determining soil characteristics, our current research primarily aims to investigate dynamic changes of the soil fraction when exposed to freeze-thaw conditions. We observed two series of Moscow morainic clayey specimens （gQⅡm）： （Ⅰ） the original series, and （Ⅱ） the remolded series. We subjected each series of soil specimens to different frequencies of freeze-thaw cycles （3, 6, 20, and 40 cycles）, and we used granulometric tests to analyze both series before and after exposure to freeze-thaw conditions. As a result of our experiments, the granulometric compositions tended to be distributed evenly after 40 freeze-thaw processes （i.e., content of fraction for 0.1-0.05 mm was increased after 40 freeze-thaw cycles） because the division of coarse grains and the aggregation of fine grains were synchronized during the freeze-thaw process. The soil grains in both series changed bi-directionally. In the original series, changes of the sand grains were conjugated with the clay grains, and in the remolded series, changes of the sand grains were conjugated with the silt grains, because potential energy difference caused the division and aggregation processes to relate to the counteraction process. The even distribution of soil grain size indicated the state of equilibrium or balance. The granulometric compositions were altered the most during the sixth freeze-thaw cycle, because the coefficient of the intensity variation of the grain fineness （Kvar） had its maximum value at that time.

Material Composition and Engineering Characteristics of Red Clay in Guigang, Guangxi

There is fine and uniform clay with aluminous and ferrous cementation in the red clay found in Guigang, Guangxi. It has the characteristics of shrinkage outwardly, rigid upper but soft lower and well grown fissure. In addition there are engineering characteristics such as high water content, low compactness and low compressibility, high strength and high contractility but slight expansibility. This paper discusses the red clay's engineering characteristics and its change regulation with depth by analyzing changes in the red clay's grain size composition, mineralogical constitution, and chemical composition.

Synthesis and Characterization of Ibuprofen-Rectorite Composites by Solution Intercalation Method

The ibuprofen-rectorite composites were prepared by the solution intercalation method using ibuprofen and rectorite as raw materials, and were characterized by X-ray diffraction （XRD） analysis, Fourier transform infrared analysis and scanning electron microscopy （SEM）. The experimental results show that the ibuprofen is intercalated into the interlayer spaces of rectorite. The values of the （001） peaks of the ibuprofen-rectorite composite are larger than that of Na-rectorite and reach the largest when the reaction time and ibuprofen amount is 2 h and 0.36 g, respectively. The layered structure of Na-rectorite is destroyed to some extent with the intercalation of ibuprofen into the interlayer space in the structure of Na-rectorite. A part of ibuprofen in the ibuprofen Na-rectorite covers on the surface of Na-rectorite besides some ibuprofen enters into the interlayer space.

Development and Characterization of Ceramic Matrix Composite (CMC) from Nigerian Kankara Kaolin and Gray Cast Iron Filling

This study developed a ceramic composite material (CMC) for use as a refractory material from “Kankara” clay (kaolin) as a matrix material mixed with gray cast iron (GCI) as reinforcement. The CMCs were prepared by varying the percentage by weight of the gray cast iron using 5, 10, 15, 20, 25, 30, 35, 40 and 45 wt%. Tests were conducted on the developed CMC, using standard test techniques, to determine physical and the mechanical properties of the produced composites. The results for mechanical properties showed improvement in the hardness value from 47% at 5% GCI content to 94% at 45% GCI content;the compressive strength improved from 3.11% at 5% GCI to a peak of 7.15% at 25% GCI and then descended down to 3.74% at 45% GCI content while the ultimate tensile strength improved from 0.75% at 5% GCI to a peak of 1.87% at 25% GCI down to 1.34% at 45% GCI content. Equally, there is an increase in bulk density from 1.74% for 5% GCI content to 2.09% for 45% GCI contentment. The linear shrinkage reduced from 11.57% to 1.15%;water absorption also reduced from 33.68% to 15.20%;apparent porosity too reduced from 42.2% to 16.02%. However, cold crushing strength initially increased with increase in GCI content from 3.89 to a peak of 13.32 V for 25% GCI content and progressively dropped to a value of 5.25 V at 45% GCI content. All the values obtained from the blends are within the recommended values for kiln shelves. However, the CMC developed on 25% GCI content showed the best combination of both mechanical and physical properties required of a good material for the production of kiln shelves.

Microstructure Evolution of Organic Matter and Clay Minerals in Shales with Increasing Thermal Maturity

As the two important components of shale, organic matter(OM) and clay minerals are usually thought to strongly influence the hydrocarbon generation, enrichment and exploitation. The evolution process of OM and clay minerals as well as their interrelationship over a wide range of thermal maturities are not completely clear. Taking Yanchang(T3y), Longmaxi(S1l) and Niutitang(?1n) shales as examples, we have studied the microstructure characteristics of OM and clay minerals in shales with different thermal maturities. The effects of clay minerals and OM on pores were reinforced through sedimentation experiments. Using a combination of field emission scanning electron microscopy(FESEM) and low-pressure N2 adsorption, we investigated the microstructure differences among the three shales. The results showed that both OM and clay minerals have strong effects on pores, and small mesopore(2–20 nm) is the dominant pore component for all three samples. However, the differences between the three samples are embodied in the distribution of pore size and the location. For the T3y shale, clay minerals are loosely arranged and develop large amounts of pores, and fine OM grains often fill in intergranular minerals or fractures. Widespread OM pores distribute irregularly in S1l shale, and most of the pores are elliptical and nondirectional. The ?1n shale is characterized by the preferred orientational OM-clay aggregates, and lots of pores in the composites are in the mesopore range, suggesting that over maturity lead to the collapse and compaction of pores under huge pressure of strata. The results of the current research imply that with increasing thermal maturity, OM pores are absent at low maturity(T3y), are maximized at high maturity(S1l) and are destroyed or compacted at over-mature stage(?1n). Meanwhile, clay minerals have gone through mineral transformation and orientational evolution. The interaction of the two processes makes a significant difference to the microstructure evolution of OM and clay minerals in shale, and the findings provide scientific foundation in better understanding diagenetic evolution and hydrocarbon generation of shale.

Clay minerals and geochemistry of the bottom sediments in the northwestern East China Sea

Clay minerals of 34 sediments collected from the northwestern continental shelf of the East China Sea have been determined by X-ray diffraction analysis. The clay mineral distribution is mainly controlled by the sediment source and the dominant circulation pattern. The predominant clay mineral in our study area is illite comprising more than 67% of the whole clay fraction. The highest concentration of illite （〉68%） is found in the southeastern offshore parts beyond the reach of terrigenous input from the Jeju Island. It means that these illites are largely transported by the Kuroshio Current from the South China Sea （SCS）. Smectite is highly concentrated in the northwest middle part and in the outer-shelf mud patch. It seems to be due to the high supply of smectite transported from China where fine-grained sediments are discharged from modern and ancient Huanghe （Yellow） River. The relatively high abundant kaolinite is likely derived from the Changjiang （Yangtze） River via the Taiwan Warm Current. In contrast, large amounts of chlorite and high chlorite/kaolinite ratios occur in the northwestern area, reflecting the transportation by the Yellow Sea Coastal Current from the southern Yellow Sea. The discrimination diagrams clearly show that the sediments in the northwestern East China Sea are ultimately sourced from Chinese rivers, especially from the Huanghe River, whereas the sediment in the northeast part might come from the Jeju Island. The muddy sediments of the Changjiang River＇s submerged delta have much lower 87Sr/S6Sr ratios （0.716 2-0.718 0） than those of the Shandong Peninsular mud wedge （0.721 6-0.724 9）, which are supposed to be originated from the Huanghe River, suggesting the distribution pattern of 87Sr/86Sr ratios as a new tracer to discriminate the provenance of shelf sediments in the study area. The 87Sr/86Sr ratios of the outer-shelf muddy sediments ranged from 0.7169 to 0.7216 in a wide range and was between those of the Huanghe River and Changjiang River sediments, suggesting multiple sources of the sediment in the area.