Raw sewage sludge was characterized by XRD, FTIR, SEM, and TGA techniques and incinerated in temperature range 650–950°C for 2 h. The effect of incineration temperature on the microstructure and pozzolanic activity of the resultant ash was investigated by techniques mentioned above as well as Chapelle test. It was concluded that incineration of sewage sludge affects the microstructure and pozzolanic activity of the resultant ash. During incineration at temperatures lower than 800°C, amorphous silica captures fixed carbon resulting from incomplete combustion conditions whereas at higher temperatures crystallization of amorphous silica was enhanced. Hydration products formed from hydrothermal treatment of silica fume with lime is amorphous whereas that of sewage sludge ash is fibrous. Hence, incineration of sewage sludge ash must be optimized at 800°C to preserve the pozzolanic activity of the resultant ash.

This paper investigated the production of alumina from Nawan kaolin by acid leaching with sulfuric and hydrochloric acids. Kaolin was calcined at 850°C and was leached with 6 M acid at 90°C, 5M NaOH followed by HCl solutions were added to the leaching liquor, and the precipitated aluminum hydroxide was converted to alumina by calcination at 900°C. Materials were characterized by FTIR, XRD, and SEM techniques. The alumina extraction percent was determined at different leaching times (30-180 min) and solid/liquid ratios (0.05-0.15 g/ml). The purity of kaolin is about 95%. The percent of extraction of alumina rapidly increases with the solid/liquid ratio up to 0.1 g/ml then decreases thereafter. The percent of extraction of alumina is higher for HCl than H2SO4. The size of the chloride and sulfate ions is the key factor that controls the percent of extraction of alumina from calcined kaolin under the studied conditions.

This paper describes the low temperature synthesis of belite (β-C₂S) from silica fume. Mixtures of lime, BaCl₂, and silica fume with the ratio of (Ca + Ba)/Si = 2 were hydrothermally treated in stainless steel capsule at 110–150°C for 2–5 hours, calcined at 600–700°C for 3 hours, and analyzed by FTIR, XRD, TGA/DTA, and SEM techniques. Dicalcium silicate hydrate (hillebrandite) was prepared by hydrothermal treatment of lime/silica fume mixtures with (Ca + Ba)/Si = 2 at 110°C for 5 hours. Hillebrandite partially dehydrates in two steps at 422 and 508°C and transforms toγ-C₂S at 734°C which in turn transforms toα′-C₂S at 955°C which in turn transforms toβ-C₂S when cooled. In presence of Ba²⁺ions,β-C₂S could be stabilized with minor transformation toγ-C₂S. Mixture of silica fume, lime, and BaCl₂with the ratio of (Ca + Ba)/Si = 2 was successfully utilized for synthesis ofβ-C₂S by hydrothermal treatment at 110°C for 5 hours followed by calcination of the product at 700°C for 3 hours.

The aim of the present study is to investigate the hydration characteristics and the fire resistance of sewage sludge ash blended cement pastes by the determination of compressive strength, bulk density, and total porosity in addition to XRD and SEM techniques. Sewage sludge ash modifies the hydration of cement because of its pozzolanic reaction with portlandite favoring the formation of crosslinked fibrous calcium silicate of low Ca/Si ratio. Hence, it was concluded that thermal damage of cement pastes after the exposure to high treatment temperatures (i.e., crack formation and loss of mechanical properties) was effectively reduced with sewage sludge as content up to 20 wt% because of that the presence of crosslinked fibrous calcium silicate strengthens the cement matrix.

This research aims to beneficiate the clay deposits abundant in the Al Baha district to produce ceramic filters for “point-of-use” household water treatment technology to remove dissolved solids from water that is no longer valid for drinking purposes to meet the needs of the community through a safe household and industrial water supply after further treatment purposes. In addition, it helps to reduce the expenses of citizens earmarked to buy drinking water. A sample of laterite, clay, and kaolin from Al Baha district was thermally treated at 800 °C, acid treated with HCl, analyzed by XRD, FTIR, and SEM, and tested for treatment of household water. The temperature, pH, electrical conductivity (EC), and total dissolved solids (TDS) were measured. In the application step for point-of-use water treatment of household water, the treated materials were introduced in calcined kaolin filters and commercial polypropylene filters. Based on the results of household water treatment with raw and treated clay materials, the raw clay materials, has poor adsorption capacity. The thermal treatment of clay samples dehydrates the clay minerals into sintered aluminosilicates and enhances the conversion of poorly crystallized iron oxide to α-Fe₂O₃ without improving the adsorption capacity of clay materials. However, the acid treatment of the clay samples removes iron-bearing minerals leaving behind amorphous aluminosilicate matter characterized with improved adsorption capacity. It was concluded that the acid treatment of clay material by concentrated HCl acid completely leaches iron oxide phases and broke down and disintegrated the clay minerals into the amorphous matter with enhanced the adsorption capacity. The combination of selected acid-treated laterite, clay, and charcoal for the household water treatment filter at the point of use in the calcined kaolin filter and the polypropylene filter reduced the TDS content by 40–42%.