Kedsarin Pimraksa

Workability and strength of lignite bottom ash geopolymer mortar.

In this paper, the waste lignite bottom ash from power station was used as a source material for making geopolymer. Sodium silicate and sodium hydroxide (NaOH) were used as liquid for the mixture and heat curing was used to activate the geopolymerization. The fineness of bottom ash, the liquid alkaline/ash ratio, the sodium silicate/NaOH ratio and the NaOH concentration were studied. The effects of the additions of water, NaOH and napthalene-based superplasticizer on the workability and strength of the geopolymer mortar were also studied. Relatively high strength geopolymer mortars of 24.0-58.0 MPa were obtained with the use of ground bottom ash with 3% retained on sieve no. 325 and mean particle size of 15.7 microm, using liquid alkaline/ash ratios of 0.429-0.709, the sodium silicate/NaOH ratios of 0.67-1.5 and 7.5-12.5M NaOH. The incorporation of water improved the workability of geopolymer mortar more effectively than the use of napthalene-based superplasticizer with similar slight reduction in strengths. The addition of NaOH solution slightly improves the workability of the mix while maintaining the strength of the geopolymer mortars.

Synthesis of zeolite phases from combustion by-products

Synthesis of zeolites from combustion by-products, including fly ash, bottom ash and rice husk ash, was studied. A molar ratio of SiO2/Al2O3 of 1.5 was used for the syntheses. Refluxing and hydrothermal methods were also used for synthesis for comparison. The reaction temperatures of refluxing and hydrothermal methods were 100°C and 130°C, respectively. Sodalite, phillipsite-K, and zeolite P1 with analcime were obtained when fly ash, bottom ash and rice husk ash were used as starting materials, respectively. With rice husk ash as a starting material, zeolite P1 was produced. This result had advantages over previous studies as there was no prior activation required for the synthesis. The concentrations and types of alkaline used in the synthesis also determined the zeolite type. The different zeolites obtained from three systems were measured for specific surface area and pore size by using BET and Hg-porosimetry, respectively. Ammonium exchange capacities of the synthesised powders containing zeolites, sodalite, zeolite P1 and phillipsite-K were 38.5, 65.0 and 154.7 meq 100 g -1, respectively.

Investigation on the Dielectric Properties of 0–3 Lead Zirconate Titanate-Geopolymer Composites

Lead zirconate titanate (PZT)-fly ash geopolymer pastes composites of 0–3 connectivity were fabricated using 30–50% by volume. The mineralogical compositions of fly ash geopolymer materials were investigated using X-ray diffraction (XRD). The 10 mol sodium hydroxide solution and sodium silicate solution at a sodium silicate-to-sodium hydroxide ratio of 0.67 were used to prepare geopolymer pastes. The pastes were cured at 60°C for 2 days. The results showed that the dielectric constant of PZT-fly ash geopolymer pastes composites decreased with increasing PZT content at 1 KHz. The dielectric properties of PZT-fly ash geopolymer pastes composites were also found to depend on the frequency.

Preparation of Zeolite Nanocrystals via Hydrothermal and Solvothermal Synthesis Using of Rice Husk Ash and Metakaolin

Synthesis of zeolite nanocrystals from rice husk ash and metakaolin was studied. Hydrothermal and solvothermal methods at 120 °C for 6 h were used as comparative study. Starting mixes were prepared with SiO2/Al2O3 molar ratio of 4. Two factors; stirring time before hydrothermal and solvothermal treatments and solvent types were studied. The synthesized products were characterized in terms of mineralogy using X-ray diffraction, specific surface area using N2 adsorption and desorption isotherm, morphology and composition using scanning electron microscopy and electron dispersion X-ray analysis. The results showed that faujasite and zeolite P1 were obtained from both of hydrothermal and solvothermal methods. However, crystals sizes of the synthesized zeolites from solvothermal method were smaller than that of hydrothermal method in that 100-300 nm and 100-1500 nm for solvothermal and hydrothermal methods, respectively. Specific surface area of the zeolites obtained from hydrothermal and solvothermal methods were 418 and 487 m2/g, respectively.

Thermal Activation on Phase Formation of Alkaline Activated Kaolin Based System

The research aim was to investigate phase development after pozzolanic reaction between metakaolin (MK) and calcium hydroxide (CH) with alkaline and thermal activations. The CH to MK ratio (C/M) of 0.4 generating CaO/SiO2 of 1.18 was selected in this study. Various concentrations of NaOH solutions (0.01, 0.1, 1, 3, 5 and 10 M) were used. The alkali activated samples were thermally activated at 25 °C, 70 °C, 90 °C and 130 °C for 4 h. Phase development under thermal activation of alkali activated metakaolin based system were investigated. At every temperature, C/M mixtures with 0.01 and 0.1 M NaOH promoted the formations of poorly crystalline calcium silicate hydrate (C-S-H(I)) and calcium aluminosilicate hydrate (CASH) compounds. With 3 and 5 M NaOH activations, sodium aluminosilicate hydrate (NASH) and sodium calcium silicate hydrate (NCSH) was formed. 1 M NaOH was found to be a boundary of phase transformation from C-S-H(I) and CASH to NASH and NCSH. In addition, zeolite X and sodalite appeared when NaOH solution reached 10 M. Thermal activation significantly affected phase development at high concentration of alkaline activation (1-10 M). At 1 M NaOH, NASH compounds in a form of gmelinite and zeolite ZK-14 were found at 70-90 °C. At 3-5 M, katoite was found at 70-130 °C. At 10 M, zeolite X was found at 70-90 °C. Sodalite was also found at 130 °C with 10 M NaOH.

Synthesis of Faujasite and Analcime Using of Rice Husk Ash and Metakaolin

Faujasite and analcime were synthesized by two-step process via hydrothermal method using the rice husk ash and metakaolin as starting materials. In the first step, the raw materials were prepared using the SiO2/Al2O3 molar ratio of 4 and pretreatment with NaOH solution under various stirring conditions. The suspension was subjected to hydrothermal treatment at various reacting time and temperature in second step. The mineralogy, morphology, specific surface area and cation exchange capacity of the synthesized products were investigated using X-ray diffraction, Scanning electron microscopy, N2 adsorption and desorption isotherm and ammonium acetate method, respectively. Faujasite was obtained using low temperature and short-time synthesis, while the analcime was obtained at high temperature and long-time synthesis. The stirring time did not affect zeolite types but the specific surface area. The cation exchange capacity of the synthetic faujasite and analcime were 263-280 and 280-302 meq/100 g, respectively.

Sulfoaluminate cement-based concrete

Abstract Sulfoaluminate cement (SAC) has been known as a low carbon and energy cementitious material as it can be produced at lower temperature, lower lime content, and improved grindability compared to ordinary Portland cement (OPC). The benefits are not limited to energy savings and low carbon emissions. In fact, SAC has promising properties that can overcome certain limitations of OPC. For example, shrinkage leading to cracks can be overcome using calcium sulfoaluminate (4CaO·3Al 2 O 3 ·SO 3 ). A ternary system of SAC with other cement phases such as dicalcium silicate and calcium aluminoferrite is more practical. Fast setting and early strength development can be accomplished rapidly due to ettringite (6CaO·Al 2 O 3 ·3SO 3 ·32H 2 O) formation. Such quick setting is one of the important properties for repair works. However, the cost of SAC is still unattractive for the construction industry due to the unavailability of raw materials. Understanding its behavior when applied to reinforced concrete is also a big issue, due to its low alkalinity that favors corrosion of steel. The replacement of OPC by SAC is, therefore, hindered in some circumstances. In order to approach sustainability for the future of the construction industry, this chapter discusses the synthesis of SAC using primary and alternative raw materials, its hydration reaction with the presences of admixtures and OPC, its durability, and its usages for concrete repair.

Alternative Cementitious Materials and Their Composites

Department of Industrial Chemistry, Faculty of Science, Chiang Mai University, Chiang Mai 50200, !ailand Sustainable Infrastructure Research and Development Center, Khon Kaen University, Khon Kaen 40002, !ailand Center for Sustainable Infrastructure, Faculty of Science Engineering and Technology, Swinburne University of Technology, Hawthorn, VIC 3122, Australia College of Civil Engineering, Hunan University, Hunan 410082, China

Development of Engobe Samples for Dan Kwian Ceramic Body

This paper developed engobe samples for Dan Kwian ceramic body. Kaolinite clay, zirconium silicate, sodium feldspar and quartz were used as raw materials which were varied to obtain various samples. Mix proportion was designed by the square sampling method to obtain 16 samples. All samples were milled and fired at 1200°C under oxidation and reduction atmospheres. The results showed that the suitable engobe composition of kaolinite clay 10 wt%, zirconium silicate 10 wt%, sodium feldspar 40 wt% and quartz 40 wt% to produce good surface appearance for Dan Kwian ceramics. Engobe surfaces and the body had no defect both in the oxidation and reduction atmospheres. The color and engobe surface were opaque white and glossy, respectively.