Clay Binder Research Articles

Rheology of Extruded Cement-Based Materials

Current research efforts seek to develop extruded high-performance fiber-reinforced cement-based composites (HPFRCC) for use in residential housing applications. Part of this effort focuses on reducing the high material cost that is associated with extrusion processing by replacing costly cellulose ethers with less expensive clay binders. The minimum amount of two different types of cellulose ethers that was needed to achieve extrudability was determined and then the possibility of reducing the ethers with two clay binders was explored. The results show that cellulose ether content can be reduced by using alternate clay binders. In addition, two different extrusion-based rheological characterization methods were used to describe the fresh state properties of the extruded materials: the Benbow-Bridgwater model and capillary rheology. Capillary rheology was shown to be effective at describing extrudability, providing an indication of the fresh state parameters necessary for extrusion.

Influence of clay binder on the liquid phase hydroisomerization of n-octane over palladium-containing zeolite catalysts

The influence of the clay binder on the properties and performance of palladium-containing zeolite catalysts in the liquid phase hydroisomerization of n-octane was studied. Three different framework zeolites with similar Si/Al ratio were used as catalysts: USY, mordenite and beta with or without binder. In all cases, a decrease in the catalytic activity of agglomerated samples, because of the modification of the acidity and the porosity of the zeolites by the binder, was observed. The decrease in the acidity after the agglomeration could be attributed to solid-state ion exchange between zeolite protons and clay sodium during the calcination of the catalyst. Moreover, the aluminium extraframework species (EFAL) created during the agglomeration process could cause a partial blocking of the micro-pore mouths, which would lead to an increase in the length of the effective diffusional pathway. After the agglomeration process, the monobranched isomers selectivity increased for all the samples while the multibranched isomers selectivity decreased. Due to the high pressure in the liquid phase, a significantly higher isomers selectivity was obtained as compared to vapour-phase conditions, and cracking became important only at relatively high average conversions.

Properties and microstructure of lightweight aggregate produced from sintered sewage sludge ash

The properties of lightweight aggregate (LWA) manufactured from the ash produced by fluidised bed incineration of sewage sludge have been investigated. The ash was mixed with a clay binder, formed into approximately spherical pellets and rapidly sintered in a rotary tube furnace at temperatures between 1020 and 1080 °C. Selected physical properties of sintered ash pellets relevant to use as lightweight aggregate have been determined, including density (apparent specific gravity), water absorption and compressive (crushing) strength. These have been compared to the properties of a commercially available lightweight aggregate (Lytag). Sewage sludge ash (SSA) pellets sintered over a range of temperatures were found to have lower densities than Lytag and low water absorption when fired between approximately 1050 and 1080 °C. Individual pellet strengths were comparable to Lytag. Major crystalline phases present in both as-received and sintered sewage sludge ash were quartz (SiO 2), the calcium magnesium phosphate mineral whitlockite (Ca 7Mg 2P 6O 24) and hematite (Fe 2O 3). Manufacturing lightweight aggregate from sewage sludge ash may become increasingly viable as landfill disposal costs continue to increase and the costs of alternative natural aggregates obtained from increasingly distant locations also increase. Sewage sludge incinerators tend to be situated in urban areas, close to where construction activity is occurring. The results indicate the potential for manufacturing high quality lightweight aggregate from the sterile, inert ash produced by sewage sludge incineration, using relatively simple processing and low temperature sintering.

Waste green sands as reactive media for the removal of zinc from water

Waste green sands are industrial byproducts of the gray iron foundry industry. These green sands are composed of fine silica sand, clay binder, organic carbon, and residual iron particles. Because of their potential sorptive and reactive properties, tests were performed to determine the feasibility of using green sands as a low cost reactive medium in permeable reactive barriers (PRBs). Serial batch kinetic tests and conventional batch sorption tests were conducted to determine the removal characteristics for zinc in aqueous solutions. Removal characteristics for zinc in the presence of green sands are comparable to those of Peerless iron, a common reactive medium used in PRBs. High removal capacities for zinc of green sands are attributed to clay, organic carbon, and residual iron particles, which are known sorptive media for heavy metals. Furthermore, high pH values in the presence of clay and residual iron particles enhanced sorption and precipitation of zinc.

Vapour adsorption capacity of controlled porosity honeycomb monoliths

When large volumes of gas have to be treated pressure drop limitations may arise from the use of conventional adsorption beds. For these applications conformation of the adsorption bed as honeycomb monoliths take advantage of the almost null pressure drop caused by these open channel structures. Commercially available microporous activated carbons, a mesoporous alumina and non-porous titania were conformed as honeycomb monoliths by addition of a silicate clay binder. The textural and mechanical properties of these monoliths were determined. The results were analysed together with the adsorption capacities towards chlorinated and non-chlorinated aromatic and aliphatic probe molecules and water vapour to establish the relationship between their textural properties and their adsorptive behaviours.

Effect of Clay Binder on Sorption and Catalytic Properties of Zeolite Pellets

Sorption of N2 ,O 2, Ar, and CH4 in zeolites X, Y, and mordenite in powder as well as pellets was studied using gas chromatography. Heats of sorption in pellets formed using clay as a binder increased by 34-78% for N2 and 7-18% for CH4 relative to the respective zeolite powder. Surface acidity of zeolites upon pelletization as measured by ammonia temperature-programmed desorption showed that high-strength acid sites completely disappear for both zeolite Y and mordenite when bound with bentonite and attapulgite. Decreases in weaker acid sites upon pelletization for mordenite and HY are 47-52% and 34%, respectively. Fourier transform infrared spectroscopy also showed a decrease in acidity upon pelletization of zeolite powders as observed from the reduction in the intensity of the peaks corresponding to acidic hydroxyl groups. Influence of the decrease in surface acidity upon pelletization was also observed from conversion values for alkylation of toluene with methanol in zeolite pellets. For example, reduction in total xylene formed was by 50%, 87%, and 100% for HY520, HY510, and HM510, respectively. These observations have been interpreted in terms of solid-state migration of cations present in clay interlayer space to zeolite extraframework sites during pelletization. Reexchange of cations in zeolites HY and HM with an aqueous solution of Na + /Ca 2+ salts shows sorption isotherms closer to the respective pelletized samples. X-ray diffraction studies of zeolites in powders as well as pellets confirm migration of clay cations to zeolite extraframework sites.

Hydroisomerization of n-butane over Pd/HZSM-5 and Pd/Hβ with and without binder

The influence of the agglomeration with a clay binder on the activity of two 3D zeolites with medium and large pore size (ZSM-5 and beta) for the hydroisomerization of n-butane has been studied. Temperature-programmed desorption of ammonia (TPDA), atomic absorption (AA) spectroscopy, chemisorption and surface area measurements were used to characterize the catalysts. Catalytic performance is strongly influenced by the binder due to the fact that zeolite hydrogen transfer activity, metal/acid site balance, acid site density, and diffusional limitations are altered after agglomeration. A lower conversion is always obtained for the binded catalysts, due to neutralization of some zeolite acid centers. For the catalysts based on ZSM-5, it is compensated by a higher selectivity to iso-butane, but this positive effect is not observed for the catalysts based on beta zeolite.

Influence of Clay Binders on the Performance of Pd/HZSM-5 Catalysts for the Hydroisomerization of n-Butane

The influence of the amount of two clay binders (montmorillonite and bentonite) on the acid properties and performance of Pd/HZSM-5 zeolite with different Si/Al ratios for the hydroisomerization of n-butane has been studied. Temperature-programmed desorption of ammonia, atomic absorption spectroscopy, chemisorption, and surface area measurements were used to characterize the catalysts. After agglomeration, some zeolite protons are neutralized by clay sodium and, consequently, a lower n-butane conversion is obtained. The product selectivity is also strongly influenced by the binder due to the fact that zeolite hydrogen transfer activity, metal/acid site balance, and diffusion of products are modified. If the appropriate binder is selected, the decrease in conversion will be compensated by a much higher isobutane selectivity. Thus, a catalyst based on Pd/HZSM-5, with a zeolite Si/Al ratio of 25, and agglomerated with bentonite in a zeolite/clay ratio of 35/65 wt/wt, showed not only an adequate mechanical resistance but also high isobutane selectivity and isobutane yield (87.1 and 23.9 mol %, respectively). It should be remarked that, under the same reaction conditions, the parent catalyst without binder showed worse isomerization activity (18.5 mol % isobutane yield with 47.3% isobutane selectivity).

Preparation of Firing Bodies from Mesoporous Materials by Selective Leaching Method and Its Water Vapor Adsorption. (Part 2).

To investigate the possibility of developing a humidity self-control material, mesoporous-powder prepared by selective leaching method was pressed and fired with adding organic binders. A comparison was carried out with a material fired with clay binder. The specific surface area, total pore volume, pore size distribution, and water vapor adsorption of the fired bodies were measured for samples prepared at various firing temperatures, to evaluate the humidity controlling properties. The amount of water vapor adsorbed by the fired bodies decreased with increasing the firing temperature of the bodies. The amount of water adsorption on the body fired at 900°C (GK33-900) at a relative humidity between 30 and 60%, and between 60 and 90% was, however, similar to that of the original powder. It was found that the dry pressing process with organic binders was more suitable than that with clay binders and it was possible to manufacture the fired body preserving the humidity self-control property.

Determination of live clay in foundry greensand by sodium-selective electrode

The rapid determination of ‘live’ clay in greensand is an essential procedure for the efficient running of a foundry production line, since progressive calcination of the clay binder during casting affects mould competence and quality of finish. A new method for assessing the active fraction of clay in foundry sand is described that is based on the response of an ion-selective electrode (ISE) to sodium ions liberated from the clay by ammonium ions. The method possesses advantages of speed and objectivity over the Methylene Blue titration method presently employed in foundries. Results appear to be unaffected by the presence of coal dust in greensand.

The influence of clay binder material on the physical properties of the CaNaA molecular sieve used in a hydrocarbon separation process

For various zeolite-binder mixtures, the mechanical properties and the sorption ability of the extruded products have been analyzed. We established an optimal composition of the binders amounting to 80% two-layer and 20% three-layer clay materials. The calcination temperature should be between 823 and 923 K. Acidic media are to be avoided in the manufacturing process.

Vacuum Sorption Pumping Studies of Argon and Oxygen on 4A Molecular Sieves

Cryosorption pumping is a method of evacuating enclosed volumes by adsorbing gas on a deep bed of sorbent, such as Davison 4A zeolite, at cryogenic temperatures. Modeling the dynamic behavior of these systems for air pumping requires information on two major constituents of air: oxygen and argon. Particle size variation was the major variable in determining the mechanism of the process. The model comprises a fluid-phase mass balance representing the dynamics of gas in the bed and a spherical, one-dimensional diffusion equation describing adsorption in pellets of 4A zeolite. The present model calculates effective pore diffusivity taking into account Knudsen diffusion, ordinary diffusion, and Poiseuille flow. The primary diffusional resistance appears to occur in the macropores formed by the pelletizing clay binder, rather than in the bed interstices or microporous zeolite crystals.

Application of differential thermal analysis in the investigation of moulding sands

On the basis of the DTA curve of clay binders it has been proved that it is possible to predict certain technological properties of quartz-clay moulding sands. Among these properties there are compression strengths, thermal durability and determining the maximum temperature of the treatment process.

Physical properties of southeastern Washington loess related to cut slope design: Beard, L D; Higgins, J D; Fragaszy, R J; Kilian, A P; Peters, A J Trans Res RecN1089, 1986, P29–38

Loess is an aeolian soil consisting primarily of silt. The silt particles along with a lesser percentage of sand are coated by a clay binder, giving loess its unique structure. Because of the lack of development in the loessial soils of southeastern Washington, little is known about their engineerng characterisics. However, recent highway construction requiring large cut slopes has prompted interest. The results of a literature review of engineering characteristics of loess and an evaluation of the physical properties of southeastern Washington loess related to design of cut slopes are presented. A map shows the general distribution of clayey, silty, and sandy loess. Results to date indicate that the basic physical properties of southeastern Washington loess are quite similar to those from deposits in the central United States. Water content tends to increase from west to east because of increasing clay content and precipitation to the east. Washigton loess has a slightly lower plasticity than midwestern deposits, possibly because of greater illite and lower montmorillinite content. Based on experience in the midwestern United States and observations of existing cut slopes in southeastern Washington, design recommendations are presented. Near-vertical cuts are recommended in silty loess with low water content, and flatter cuts (approximately 2.5:1 H:V) are recommended in clayey loess and silty loess with high water content. Adequate surface drainage is a key factor of slope design. erest.

Process design for the production of a ceramic-like body from recycled waste glass

The influence of fabrication variables on the sintering behaviour of a ceramic-like body containing 90% recycled waste glass was inferred from measurements of some of the fired properties (moduli of rupture and elasticity, firing shrinkage, bulk density and porosity). Interpretation of these results in terms of viscous sintering theory indicates the relative influence on the sintering behaviour of factors such as particle size and distribution, clay binder content and plasticity, pressing pressure, heating/cooling rate, firing temperature and time, thus enabling the fabrication variables to be optimized. Comparison of the physical properties of the resulting glass-based bodies with those of commercial ceramic tile bodies indicates that the glass-based bodies are very comparable with the best ceramic tiles tested, and considerably better than several commercially-produced clay-based bodies.

Binders Used in Ceramic Industry

Plastic clay has been a natural binder material for ceramic manufacture from the beginning of making pottery and it continues to find extensive usage even to-date. The conventional clay binder, however, is found to be inadequate in various fields of application, particularly when material other than clay is used for ceramic fabrications.A survey of the alternate binder materials has been made in this paper and their impact on the ceramic fabrications of the modern day is discussed. Mechanism causing setting and strength development in the binders is briefly elucidated.

Temperature dependence of gas conductance through porous silicon carbide plugs

Abstract A simple technique for gas flow stabilization in vacuum systems is described. The gas conductance through porous silicon carbide plugs is shown to fall by a factor of 2.5 for the gases He and Ne as the plug temperature is increased from 77K to 800 K. The conductance falls by a factor of 2 for Ar, Kr, N 2 and CO 2 between room temperature and 800 K. The negative temperature coefficient of gas conductance through the plugs is satisfactorily explained by a simple analytical expression. It is suggested that the presence of clay binder material used in the manufacture of the plugs is a major factor in determining the conductance variations.

On the Retained Strength in Various Sand Molds with Bentonite and Kibushi Clay Binders

On the Retained Strength in Various Sand Molds with Bentonite and Kibushi Clay Binders

Effect of binder material on hydrocracking activity of platinized zeolite catalysts

1. It has been shown that platinized catalysts prepared from zeolites with a high silicate modulus have considerably higher hydrocracking activities than do catalysts prepared from low-silica zeolites. 2. It has been established that the type of binder has a substantial influence on the activity of high-silica catalysts, governed by the transport-diffusional pore structure of granulated catalysts. 3. It has been shown that the best catalytic, diffusional, and mechanical properties are shown by catalysts prepared by high-silica zeolites with a kaolinite (Glukhov clay) binder.

The use of protective glass coatings during heat treatment of machine parts

A glass coating consisting of frit with water-fire clay binder and 25% Al2O3 prevents oxidation and decarburization of structural and tool steels during heat treatment.