Papers by Keyword: Kaolin

Abstract: This study finds the chemical composition and the fineness of natural cement at different proportion of raw meal at firing temperature of 800°C for 8 hours. The raw mixture is prepared with limestone (calcium carbonate (CaCO)) and kaolin (Al₂O₃·2SiO₂·2H₂O). The ratios of kaolin: limestone are varied from 1:9, 1.5:8.5, 2:8, 2.5:7.5, 3:7 and 4:6. The elements intensities in the samples are determined using x-ray diffraction (XRD) test via EVA software. The elements observed at 2-theta scale are oxides of calcium, silicon, iron, magnesium and aluminum. Reducing the amount of kaolin reduces the intensity of calcium oxide. Iron oxide and silica oxide in combination with other elements intensities increase when amount of kaolin is increased. The magnesium oxide content is also high but comparable with the values from natural cements available. The mixes become finer as more kaolin is added with its specific surface values more than 3000 cm²g^-1. The mixes become finer as more kaolin is added with values more than 3000 cm2g-1. Further tests need to be done to determine suitability of kaolin as replacement of limestone in natural cement.

Abstract: Kaolin, a geopolymer raw material that is rich with aluminosilicate materials is mixed with alkaline activator solution to produce geopolymer based coating material. Geopolymer technology is stil under studied in terms of coating applications especially using kaolin as raw material. Till date, there are no similar work as our effort in this research. Lumber wood is used as our subtrates as it has low grade wood properties such as low resistance to heat, impact or even durability. In this work, optical microscopy data are analysed in support of flexural properties of kaolin coated lumber woods. As discussed in our previous work, flexural properties shows that at solid/liquid ratio of 0.7, silicate/NaOH ratio of 0.40 and 8M of NaOH, kaolin coated lumber is at its best. Our findings on interfacial micrographs of kaolin geopolymer coating and wood substrates are further observed and studied.

Abstract: The object of this work was to use calcined kaolin-based geopolymer as an alternative material to replace ordinary Portland cement (OPCs) by applying geopolymerization processes. Geopolymer slurry was prepared from calcined kaolin and alkali activators, which consisted of 10 M NaOH and Na₂SiO₃ solution. The fresh slurry was cast into plastic molds and then cured at room temperature for 24 h. Reaction temperatures were measured (for 24 hours after casting). Compressive strength of the geopolymer was tested after curing at room temperature and after microwave heating. The mechanical properties increased with added plaster for microwave curing of 5 min. It is believed that this process can increase the efficiency of the production line for geopolymer.

Abstract: Lampang, a province in northern Thailand, is the important source of ceramics raw materials, such as kaolin, pottery stone, and ball clay. This study aims to investigate the new ceramics bodies by using these local raw materials. About 50 samples from 15 sources were collected to analyze the chemical composition, mineral composition, and physical properties. Kaolin samples principally consisted of quartz and kaolinite. Its greyish color after firing at 1200 °C made it suitable for stoneware product that does not require white body. The principal ball clay mineral is kaolinite, associated with illite and quartz. All ball clay samples are high strength, which are suitable for tableware production. Pottery stone which can be found at Kaolin deposit, showed a mixed mineralogy of quartz, albite, and muscovite, while some samples showed the presence of kaolinite. It showed significantly low on shrinkage. Pottery stone are widely used as flux in both ceramics body and glaze. These analyzed characteristics were put into the ceramics raw materials database which can be searched on-line. This data is useful for the researching of ceramics body compositions with mainly contained raw materials from Lampang.

Abstract: Mullite-cordierite ceramics was prepared by the three composition of talc, kaolin (kaolin from Naratiwas in Thailand) (NT) and alumina. The different amounts of alumina (5, 10, 15 and 20 wt%) were added to produce various mullite-cordierite alumina mixtures which are denoted as NA, NB, NC and ND, respectively. The mixtures were pressed into rectangular shapes by hydraulic press with the pressure of 150 kg/cm² then sintered at temperature of 1300 °C and 1350 °C for 2 hours. The morphology of the synthesized mullite-cordierite samples were characterized by x-ray diffraction spectroscopy (XRD), and physical-mechanical properties were investigated. Mullite-cordierite was successfully synthesized. The XRD result was represented phases of mullite and cordierite. The NA samples sintered at temperature of 1300 °C indicated the best physical-mechanical properties including bulk density (2.23 g/cm³), flexural strength (44.4 MPa) and thermal expansion coefficients (5.00x10^-6). The other NA samples sintered at temperature of 1350 °C exhibited the bulk density, flexural strength and thermal expansion coefficients are 2.21 g/cm³, 47.8 MPa and 4.99 x10^-6, respectively. The thermal expansion coefficient of the NT sintered samples have been plotted the length change relative to measuring temperature ranging of 30-1200 °C. The suitable condition of the synthesized mullite-cordierite ceramics is finally obtained the NA samples with 5 percent weight of alumina composition sintered at the temperature of 1350 °C.

Abstract: The thesis deals with the study of influence of the foaming agent Schäumungsmittel W 53 addition on the specific weight and mechanical characteristics of mullite based heat insulating refractory castables. The effect of dosing and mixing time was observed in this work. The influence of partial substitution of mullite matrix by kaolin was also studied. Kaolin was added in dry matter or in the foamed state. Optimal dosage of the agent was 0,25 % and the optimal mixing time was 10 min. The addition of kaolin was the most effective in the foamed state.

Abstract: A series of (x) paper ash- (80-x) cullet – 20 Kaolin clay where 10 ≤x≤30 weight % has successfully been prepared using solid state reaction method. The ceramic density and hardness has been determined using Archimedes and Vickers hardness method respectively. The dielectric constant and dielectric loss has been determined using impedance analyzer. The obtained density is descending from 2.18 gcm^-3 to 1.90 gcm^-3 and hardness is increased up to 871.8 Mpa. The decrement of density and hardness as the cullet content increases is due to the non uniform vitreous areas formed in between ceramic particle. The variation of the dielectric constant and dielectric loss tangent are found to decrease with increasing of frequency which suggest the dipolar polarizability properties. It is found that the maximum value of dielectric constant is 3000 and minimum dielectric loss tangent is 0.166.

Abstract: This research use metakaolin and clay containing amorphous silica and alumina after calcination at 700°C. Mechanical properties and fire resistance of geopolymer paste increase as the ratio of silica to alumina. Mix design composition on this research based on the ratio of silica to alumina. The ratio of silica to alumina for metakaolin paste are 1.4 and 1.8. While for clay paste the ratio that used are 2.8 and 3.2. Na₂SiO₃ and NaOH with 10 M and 8 M were used as alkali activator at this research. Based on analysis the effect of increasing the ratio of silica to alumina increase fire resistance ability for both metakaolin and clay. However initial compressive strength is effected not only by ratio of silica to alumina but also the ratio of water to solid and SiO₂/Na₂O. The compressive strength decrease as the ratio of water to solid increases. Meanwhile compressive strength increase as the ratio of SiO₂/Na₂O increase.

Abstract: Kaolin, an abundantly available material that mainly contains alumina and silica is now being used in geopolymer system. Kaolin based geopolymer has been proven to acquire remarkable thermal resistance, chemical resistance, and mechanical properties. Geopolymer materials have become the new favorite, especially for the carbon conscious end users as a potential replacement for widely used Ordinary Portland Cement (OPC). This works shares the effect of various mix designs, especially in terms of altering the solid/liquid ratio, sodium silicate/sodium chloride ratio and sodium chloride molarity on the flexural properties of kaolin coated lumber woods via geopolymer technology.

Abstract: Properties of geopolymer coating on nonmetallic substrates, especially glass fiber-reinforced epoxy (GRE) have been considered based on the effect of Si/Al ratio and surface treatment at a determined proportion of solid to liquid (S/L) and curing temperature.Kaolin and white clay have been used as geopolymer raw material in study of adhesive strength in geopolymer coating. Effect Si/Al ratio and surface treatment on adhesive strength has been tested from 0.40-0.60using Elcometer 106 Pull Off. The answer shows that Si/Al ratio and surface treatment were effecting the adhesive strength of geopolymer coating. The highest adhesive strength 6.0 MPa was found ina Si / Al ratio of 3.5 with surface treatment.