Effect Of Clay Addition Research Articles

Mechanical and Thermomechanical Properties of Clay-Cowpea (Vigna Unguiculata Walp.) Husks Polyester Bio-Composite for Building Applications

This study investigates the feasibility of creating a clay polymer-based composite using cowpea husk (CPH) as filler for production of roof tiles. Polymeric composites were fabricated by mixing unsaturated polyester (UPT) resin with cowpea husk at different filler weights and curing. A hybrid composite was produced with the addition of 3 wt.% clay and all samples produced were subjected to flexural, hardness and dynamic mechanical analysis (DMA) tests. The effect of clay addition on the mechanical and thermo-mechanical behaviour of formulated composites was investigated. The morphological analysis of the mono and hybrid system shows a rough and coarse inhomogeneous surface with voids created due to the addition of CPH filler for the mono reinforced and clay uniformly filling the voids that were created by the CPH in the hybrid composite. It is observed that hardness, tensile modulus and flexural modulus of hybrid composites increase with an increase in the CPH contents, while the strength and flexural strength all decrease with filler content. The optimal composition was obtained using Grey relational analysis (GRA) at 18% CPH for both mono and hybrid composite. The results imply that the composite combination can be used in making rooftiles and/or also in applications where low strength is required.

The Effect of Clay Addition on the Mechanical Strength of Unsaturated Polyester Hybrid Composite Reinforced with Woven Agel Leaf Fiber/Glass Fiber

In the field of material technology, natural fiber materials are candidates for reinforcement in the production of lightweight, high-strength, environment-friendly, economical composites. Hybrid composites are comprised of a variety of reinforcement, fillers, and polymers. The objective of this research was to figure out the effect of clay addition on the mechanical properties of hybrid composites reinforced with woven agel leaf fiber/glass fiber. The materials used included woven agel leaf fiber, glass fiber, clay, Yukalac BQTN 157 type unsaturated polyester resin, and methyl-ethyl ketone peroxide catalyst. Firstly, the woven agel leaf fiber was given an alkaline treatment by submersion in a 4% NaOH solution for 1 hour, then rinsed with clean water and dried in the open air for 48 hours. The composite manufacture process employed 3 sheets of woven agel leaf fiber and 4 sheets of glass fiber sized 25 cm × 20 cm with unsaturated polyester matrix. The manufacture method used was the vacuum bagging method with a suction pressure of –70 cmHg. The mechanical tests carried out consisted of tensile test (based on the ASTM D638 standard), bending test (based on the ASTM D790 standard), and impact test (based on the ASTM D5942 standard). The results show that an addition of 1 wt% clay was able to increase the tensile strength, bending strength, and impact strength of the hybrid composite reinforced with woven agel leaf fiber/glass fiber by 7.26%, 30.85%, and 36.25%, respectively.

EFFECTS OF CLAY ON PROPERTIES OF CONCRETE

Concrete is a versatile and most prevalent construction material. Its long-term performance depends on its interactions with the surrounding environment. The standards limit the ratio of the clay in aggregates due to its harmful effect on the concrete properties. This research paper presents the effect of different levels of clay addition on the concrete properties. Various levels of clay addition for different mixes were used in this experimental study. The effect of clay addition on workability, compressive strengths permeability and acid attack of concrete mixes was investigated. It has been seen that workability decreased by increasing the clay content to the mix. A drop in compressive strength of concrete up to 12% was observed by adding clay as compared with that of control samples. An adverse effect on resistance to permeability and acid attack of concrete was noted by increasing the clay content.

Soil Respiration, Microbial Biomass C and N Availability in a Sandy Soil Amended with Clay and Residue Mixtures

Crop yields in sandy soils can be increased by addition of clay-rich soil, but little is known about the effect of clay addition on nutrient availability after addition of plant residues with different C/N ratios. A loamy sandy soil (7% clay) was amended with a clay-rich subsoil (73% clay) at low to high rates to achieve soil mixtures of 12%, 22%, and 30% clay, as compared to a control (sandy soil alone) with no clay addition. The sandy-clay soil mixtures were amended with finely ground plant residues at 10 g kg−1: mature wheat (Triticum aestivum L.) straw with a C/N ratio of 68, mature faba bean (Vicia faba L.) straw with a C/N ratio of 39, or their mixtures with different proportions (0%–100%, weight percentage) of each straw. Soil respiration was measured over days 0–45 and microbial biomass C (MBC), available N, and pH on days 0, 15, 30, and 45. Cumulative respiration was not clearly related to the C/N ratio of the residues or their mixtures, but C use efficiency (cumulative respiration per unit of MBC on day 15) was greater with faba bean than with wheat and the differences among the residue mixtures were smaller at the highest clay addition rate. The MBC concentration was lowest in sole wheat and higher in residue mixtures with 50% of wheat and faba bean in the mixture or more faba bean. Soil N availability and soil pH were lower for the soil mixtures of 22% and 30% clay compared to the sandy soil alone. It could be concluded that soil cumulative respiration and MBC concentration were mainly influenced by residue addition, whereas available N and pH were influenced by clay addition to the sandy soil studied.

Permeability of Clay Concretes

This paper presents an investigation on the effect of clay addition on water permeability and air permeability of concretes. Clay concrete mixes consisted of 0 to 40% clay content incorporated as cement replacement. Flow methods using triaxial cells and air permeameters were used for measuring the injected water and air flows under pressure. It was found that the higher the clay content in the mixture, the greater the permeability. At higher water-cement ratios (w/c), the paste matrix is less dense and easily allows water to ingress into concrete. But at high clay contents of 30 to 40% clay, the variation in permeability was significantly diminished among different concrete mixtures. It was confirmed that air permeability results were higher than the corresponding water permeability values when all permeability coefficients were converted to intrinsic permeability values.

Effect of Clay Addition on the Properties of Carbon Nanotubes-Filled Immiscible Polyethylene/Polypropylene Blends

The effects of organically modified clay (OMC) incorporation on the microstructure and the electrical and mechanical properties of polypropylene (PP)/polyethylene (PE) blends filled with carbon nanotubes (CNT) were investigated. All blends were prepared by melt mixing in a batch mixer. The microstructures were characterized by scanning electron microscopy. In the OMC:CNT filled blends, the CNT were found to selectively localize within the PE phase, while the clay particles were observed in the PP phase. The electrical resistivity of OMC:CNT filled blends did not show any significant change as a result of the clay addition since it was localized in the CNT-free phase. On the other hand, the addition of clay degraded the blends' mechanical properties due to the poor adhesion between the OMC and the PP matrix.

Investigation of corrosion protection performance of epoxy coatings modified by polyaniline/clay nanocomposites on steel surfaces

In this study, polyaniline (PANI) and polyaniline/clay nanocomposites were prepared via in situ oxidative polymerization. The morphology of nanocomposites structures was investigated by X-ray diffraction (XRD). The chemical structures of PANI and PANI/clay nanocomposites were examined via Fourier transform infrared (FT-IR) spectroscopy. Polyaniline-based pigments were introduced into epoxy paint and applied on steel substrates. The effect of clay addition and the type of clay cation, including Na+ in natural clay (MMT) and alkyl ammonium ions in organo-modified montmorillonite (OMMT), on the anticorrosion performance of epoxy-based coatings was investigated through electrochemical Tafel test, electrochemical impedance spectroscopy and immersion measurements in NaCl solution. The stability of the adhesion of the neat and modified epoxy coatings to the steel surface was also examined. The results indicated that introduction of PANI/OMMT nanocomposite into epoxy paint results in improved anticorrosion properties in comparison with PANI/MMT and neat PANI.

Phosphate sludge: Thermal transformation and use as lightweight aggregate material

Phosphate sludge generated from beneficiation plants of Moroccan phosphate rocks was investigated at 900–1200 °C by X-ray diffraction, scanning electron microscopy, thermal analysis and Fourier-transform infrared spectroscopy. Mixtures of the phosphate sludge and a swelling clay (up to 30 wt.%) were investigated and their properties (shrinkage, density, water absorption and compressive strength) were measured as a function of temperature and clay addition. The results showed that gehlenite neoformed from lime of decomposed carbonates and breakdown products of clay minerals and that fluorapatite (original mineral) resisted heating until fusion. The measured properties were mainly controlled by temperature, and the effect of clay addition was less regular, except for water absorption. Considering the mixtures densities (1.44–3.02 g/cm3), lightweight agglomerates can be produced at 900 or 1100 °C, but their compressive strengths were relatively low (2–4.5 MPa). Based on SiO2–Al2O3-Fluxes diagram and taking account of the chemical composition of the materials used, the production of expanded aggregates requires clay additions as high as 80 wt.%.

Preparation and Properties of Clay-Reinforced Epoxy Nanocomposites

The clay-reinforced epoxy nanocomposite was prepared by the polymerization method. The effect of clay addition on the mechanical properties of epoxy/clay nanocomposites was studied through tensile, flexural, impact strength, and fracture toughness tests. The morphology and tribology behavior of epoxy/clay nanocomposites were determined by X-ray diffraction (XRD) and wear test, respectively. The wear test was performed to determine the specific abrasion of the nanocomposites. In addition, the water absorption characteristic of the nanocomposites was also investigated in this study. XRD analysis indicated that the exfoliation structure was observed in the epoxy nanocomposites with 3 wt% of clay, while the intercalated structure was shown at 6 wt% of clay. It was found that the addition of clay up to 3 wt% increased the tensile strength, flexural strength, impact strength, and the fracture toughness. On the contrary, the presence of above 3 wt% of clay produced a reverse effect. It could be concluded that the best properties in mechanical, wear resistance, and water resistance were obtained for the epoxy nanocomposites containing 3 wt% of clay.

Effect of Clay Addition on Mechanical Properties of Unsaturated Polyester/Glass Fiber Composites

Unsaturated polyester (UP)/glass fiber/clay composites were prepared by hand layup method. The effect of clay loading on the morphological and mechanical properties of UP/glass fiber composites was investigated in this study. X-ray diffraction (XRD) was used to characterize the structure of the composites. The mechanical properties of the composites were determined by tensile, flexural, unnotched Charpy impact and fracture toughness tests. XRD results indicated that the exfoliated structure was found in the composite containing 2 wt% of clay while the intercalated structure was obtained in the composite with 6 wt% of clay. The tensile strength, flexural strength, and flexural modulus of the composites were increased in the presence of clay. The optimum loading of clay in the UP/glass fiber composites was attained at 2 wt%, where the improvement in in tensile strength, flexural strength, and flexural modulus was approximately 13, 21, and 11%, respectively. On the other hand, the highest values in impact toughness and fracture toughness were observed in the composites with 4 wt% of clay.

Effect of clay addition on service properties of a developed OPF–CNSL–formaldehyde roofing material

In this study, the properties of locally developed composites for roofing purposes were investigated. With the addition of varying compositions of clay, cashew nut shell liquid (CNSL)–formaldehyde was reinforced with oil palm fiber (OPF) to produce six experimental mixes. The composites were fabricated from each mix with 0.25wt.% OPF by hand lay-up approach followed by compression molding. The overall service properties were optimum when the clay content was in the ranges of 30–35wt.%. It was established that within this range of clay content, the composites can be suitable for the production of roofing material.

Ceramic clay reduces the load of organic matter and bacteria in marine fish larval culture tanks

Ceramic clay has been increasingly used to improve contrast and prey detection in tanks for rearing of fish larvae. In contrast to live microalgae or algae pastes, clay increases turbidity without contributing to the organic matter load. In addition, clay may aggregate and sediment organic matter and bacteria, facilitating its removal. Marine larvae are sensitive to infections by opportunistic bacteria. Fish, algae, and live feed increase the microbial carrying capacity of the rearing water which allow exponential growth of bacteria and favor fast-growing opportunists. Reducing substrate levels by replacing microalgae with clay may reduce bacteria proliferation and benefit larvae. We compared the effects of three rearing regimes including live Isochrysis galbana, Nannochloropsis oculata paste, and ceramic clay on the bacterial community, concentration of organic matter, and growth and survival of Atlantic cod larvae (Gadus morhua L.). The application of clay resulted in reduced substrate levels for bacteria in the rearing water compared to the addition of live algae or algae paste. To some extent, clay aggregated and transported organic matter to the bottom of the larval fish tanks, where it could be effectively removed. Fish tanks receiving clay showed a lower abundance of bacteria in the water than tanks added algae paste or live algae. Fish tanks with algae paste showed a higher abundance of bacteria and a higher share of cultivable bacteria and TCBS counts than the other two treatments. Tanks with live algae showed low relative abundances of opportunistic bacteria and TCBS counts in both water and rotifers. Cod larvae in tanks with clay or live algae initiated exponential growth earlier than larvae in tanks with algae paste. Larvae in tanks receiving clay had significantly higher dry weight than larvae in tanks receiving algae paste at day 5 and 20 post hatching. The survival of larvae in the tanks added clay was variable. Two of the three tanks with clay had significantly higher larval survival than the tanks with live algae or algae paste. However, one tank with clay underwent 100% mortality. It is not possible to conclude whether this was related to the use of clay or an incidental development of a harmful microbial community in this tank. The effects of clay addition on larval performance should be studied further. Clay addition appears to be an easy way to reduce bacterial load during early first feeding of marine larvae without compromising the beneficial effects of turbidity.

Effects of clay addition on soil protease activities in Andosols in the presence of cadmium

Pollution by heavy metals such as cadmium (Cd) is hazardous to soil microbial function, including enzyme activities. However, the addition of clay to soils may control the negative effect of Cd by both adsorption of the metal ion onto the clay and stabilization of the soil enzymes. We investigated the effects of clay addition on the activities of soil proteases in the presence of Cd using a short-term laboratory incubation experiment. The clays were separated from the soil samples used in the study. Our experiment was done at three levels of clay and Cd addition (0, +5 and +10% of original clay content, and 0, 10 and 50 mg Cd kg−1 soil, respectively) to two surface soil samples of Andosols obtained from a forest and a cultivated field in an upland area of Japan’s Kanto district. We determined the protease activities, protein content, soil pH and exchangeable Cd in both soil samples after 0, 2, 10 and 40 days of incubation. Mineralogical analysis by dissolution with acid ammonium oxalate solution on the clay fractions from both the forest and the cultivated field soil samples showed that they were largely composed of allophane (probably including imogolite) and ferrihydrite. Allophanic clay had a significant positive effect on proteases activities even in the presence of Cd, although the addition of Cd decreased protease activities, protein contents and soil pH in both soil samples in all clay treatments during incubation. Protease activities were negatively correlated with the amounts of exchangeable Cd, but the addition of clay did not have a significant recovery effect on inhibition by Cd. These results indicate that allophanic clay enhances the activity of proteases owing to stabilization of the enzyme, and that allophanic clay has little capacity to adsorb Cd2+.

Influence of Clay Addition on Physical Properties and Wettability of Peat-growing Media

The role of clay incorporation on the physical properties and wettability of peat-growing media was assessed from water retention curves and from contact angle and water drop penetration time measurements, respectively. Two peat substrates presenting different degrees of decomposition (weakly and highly decomposed Sphagnum peat) were used and mixed with clay in the form of powder with a peat:clay ratio of 90:10 (by vol.). Results indicated relatively little change in water retention resulting from clay incorporation in the peat-growing media tested. On the other hand, they showed a significant improvement of the wettability of both substrates in the driest conditions when peat-growing media presented a pronounced hydrophobic character, whereas the wettability of materials was not changed in the wettest conditions when they were largely hydrophilic. The influence of the degree of peat decomposition was also observed with somewhat higher wettability for the weakly decomposed peat:clay mixture than for the highly decomposed peat:clay mixture. Because the hydrophobic character of highly decomposed peat is more pronounced and appears at a higher water content than weakly decomposed peat, the effect of clay addition also appears at higher water contents for highly decomposed peat. Incorporating clay into peat-growing media should be considered for its ability to improve the wettability of growing media with a hydrophobic character (i.e., to improve the ability of the growing media to be rewetted) rather than only its ability to influence the water retention characteristics of the growing media.

Epoxy-Clay Nanocomposites and Hybrids: Synthesis and Characterization

This paper deals with the effect of clay addition on improving the mechanical properties of epoxy polymer and glass fiber-reinforced epoxy-clay hybrid composites. The clays used in the present system were alkyl ammonium treated montmorillonite (MMT) based organoclay (OC) and unmodified MMT clay (UC). The OC and UC were added individually to epoxy polymer and glass fiber-reinforced epoxy composites. Structure and morphology of epoxy filled with OC and UC were examined by X-ray diffraction (XRD) and transmission electron microscope (TEM) techniques. It is observed that the clay nanolayer dispersion takes place in a polymer matrix filled with OC particles. However, the UC filled composites show the formation of micro-composites. The effects of clay addition (1—3%, 5% and 10% by weight) in epoxy polymer shows that OC filled composites possess enhanced tensile strength over UC filled composites. A similar result is observed in the OC filled glass fiber-reinforced epoxy composites. Dynamic mechanical analysis (DMA) and thermogravimetry analysis (TGA) of hybrids show that the addition of OC increases the thermal properties of epoxy-glass fiber more than that of UC filled hybrids.

Effect of Shear on Phase-Separation in Polystyrene/Poly(vinyl methyl ether)/Organoclay Nanocomposites

Blends of polystyrene (PS)/poly(vinyl methyl ether) (PVME) modified with two types of organoclay were prepared by solution casting from toluene. The effect of clay addition on the phase separating morphology of PS/PVME blend with critical composition (25/75) was examined both under quiescent conditions and under shear flow. The variation in critical temperature of phase separation was assessed by rheology, small angle laser light scattering (SALLS) and by on-line laser light transmission during shearing at fixed shear rate during heating. Transmission electron microscopy and X-ray diffraction analyses were used to examine the state of delamination and distribution of clay nanoparticles with the blend matrix.

Effect of clay addition on the morphology and thermal behavior of polyamide 6

AbstractThe nanostructure, morphology, and thermal properties of polyamide 6 (PA6)/clay nanocomposites were studied with X‐ray scattering, differential scanning calorimetry (DSC), and transmission electron microscopy (TEM). The wide‐angle X‐ray diffraction (WAXD) and TEM results indicate that the nanoclay platelets were exfoliated throughout the PA6 matrix. The crystallization behavior of PA6 was significantly influenced by the addition of clay to the polymer matrix. A clay‐induced crystal transformation from the α phase to the γ phase for PA6 was confirmed by WAXD and DSC; that is, the formation of γ‐form crystals was strongly enhanced by the presence of clay. With various clay concentrations, the degree of crystallinity and crystalline morphology (e.g., spherulite size, lamellar thickness, and long period) of PA6 and the nanocomposites changed dramatically, as evidenced by TEM and small‐angle X‐ray scattering results. The thermal behavior of the nanocomposites was investigated with DSC and compared with that of neat PA6. The possible origins of a new clay‐induced endothermic peak at high temperature are discussed, and a model is proposed to explain the complex melting behavior of the PA6/clay nanocomposites. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 1191–1199, 2007

Treatment of pulping effluents by using alum and clay - colour removal and sludge characteristics

The effect of clay addition during alum coagulation, on the removal of colour from pulp-and-paper industry wastewaters, was investigated. Four types of clay, namely beige-and brown-sepiolites, calcium- and sodium-bentonites of different mesh sizes were used. Different quantities of alum and clay were applied, either singly or in combination, to the effluents of the wood-based pulp-and-paper mill. Colour of the treated wastewater, the sludge volume index (SVI) and sludge cake resistance (SCR) of the sludge produced were monitored. It was observed that the clays tested were not efficient in colour removal when they were applied on their own. When clay was added along with alum, a certain increase in colour removal efficiency was obtained as compared to alum alone. When alum was used in conjunction with clay, settling characteristics of the sludge produced improved substantially, in terms of both SVI and SCR. Acid activation of the clays did not improve the colour removal efficiency further. However, acid activation of sodium bentonite caused the SVI and SCR values to improve considerably compared to virgin sodium bentonite. Use of different mesh sizes of clays did not exert any significant effect on the colour removal. However, it did exert significant effects on SVI and SCR values as such that the increase in mesh size caused the SVI values to decrease and the SCR values to increase. WaterSA Vol.27(3) 2001: 361-366

The effect of clay addition and gypsum application on the physical properties of a hardsetting red-brown earth, and the response of irrigated cotton

The growth of furrow-irrigated cotton on red-brown earths (Alfisols) of the lower Macquarie Valley in New South Wales (Australia) is often restricted by slow water penetration and poor seedling emergence, associated with structural instability and hardsetting of the soil surface. However, local landholders have overcome the problem to some extent by increasing clay content at the soil surface by using deep mouldboard ploughing (to 0.45 m) and subsequent gypsum applications. A study was carried out to determine how mouldboarding had changed the physical condition of a red-brown earth near Narromine, why the water relations had been improved, and why the effect of this operation does not appear to be permanent. Cotton growth was measured at two sites, one ploughed and treated with gypsum (PG) and the other without these treatments (C). Both sites were also deep ripped just before planting. Field studies were complemented with laboratory experiments in an attempt to separate the effects of texture modification and gypsum application. The hydraulic conductivities of surface soil and a surface-subsoil mix, each with and without gypsum, were measured. The time for columns of these soils 0.05 and 0.2 m in height to wet to the surface, and their degree of expansion or slumping on wetting, were also determined. Cotton growth was over 100% greater where the PG treatment had been applied. This improvement was associated with greater, and more uniform, water penetration into the furrows and ridges. Despite a reduction in organic matter content and exchangeable Ca: Mg ratio, and an increase in exchangeable sodium percentage, soil from the PG site had a lower dispersion index and strength, and higher hydraulic conductivity and electrical conductivity near the surface. It also had more clay in the surface, and a higher content of smectite. The hydraulic conductivity experiment suggested that gypsum may have a similar beneficial effect on both sites. In contrast, the rate of wetting experiment, which gave a better simulation of soil physical processes in the field, showed that even with gypsum the C treatment could not maintain a favourable structure. The need for further experimentation is discussed.