Effect of Synthetic and Natural Zeolite on ASR Expansion

The cation exchange capability (CEC), pozzolanic reaction, and filling effects are important keys of natural zeolite for mitigation of Alkali Silica Reaction (ASR), but variation of the zeolite's composition is a major problem when it is utilized. This may not be the case for synthetic zeolite. This paper presents the effects of natural and synthetic zeolite on Alkali Silica Reaction's expansion control. The percentage cement replacement of synthetic and ground natural zeolite-clinotilolite type (SZ and NZ) varied from 0 to 10 and 0 to 20, respectively. It was found that the large percentage replacement (10-20%) changed behaviors of fresh and hardened mixtures significantly. Large replacements of SZ (i.e., 7.5%and 10%) significantly reduced workability and compressive strength, and increased expansion. Slight reductions in expansion were even found for the use of small percentage replacement (SZThe cation exchange capability (CEC), pozzolanic reaction, and filling effects are important keys of natural zeolite for mitigation of Alkali Silica Reaction (ASR), but variation of the zeolite's composition is a major problem when it is utilized. This may not be the case for synthetic zeolite. This paper presents the effects of natural and synthetic zeolite on Alkali Silica Reaction's expansion control. The percentage cement replacement of synthetic and ground natural zeolite-clinotilolite type (SZ and NZ) varied from 0 to 10 and 0 to 20, respectively. It was found that the large percentage replacement (10 - 20%) changed behaviors of fresh and hardened mixtures significantly. Large replacements of SZ (i.e., 7.5% and 10%) significantly reduced workability and compressive strength, and increased expansion. Slight reductions in expansion were even found for the use of small percentage replacement (SZ < 5.0%). Chemical analysis and strength reactivity index tests revealed the non-pozzolanic properties of synthetic zeolite, but not the ground natural zeolite (NZ). The NZ exhibited both pozzolanic reactivity and the capability to significantly reduce expansion. At 20% replacement of NZ, the expansion significantly reduced to none at 14 days of acceleration and less than 0.02% at the longer duration of 28 days. It was confirmed that the high CEC of the studied synthetic zeolite is not the key factor for the effective mitigation for ASR

Synthesis and Evaluation of Zeolite Surface-Modified Perlite

Perlite is volcanic glass mainly composed of amorphous aluminum silicate, mainly composed SiO2 and Al2O3 with less impurities such as heavy metals. Amorphous (glassy) perlite is used in lightweight aggregate and insulation. In addition, it has also been used as a filter aid by grinding the expanded perlite. However, it has not been used as environmental cleanup materials, because the ion exchange capacity of the perlite is very low. In this study, we tried to synthesize the hybrid filter aid with chemical adsorption capacity by synthesizing the zeolite on the surface of the perlite. As a result, by using the hydrothermal synthesis method, zeolite surface modified perlite was synthesized in which the LTA type zeolites were generated on the surface of the perlite

Preparation of Ceria Fibers Via Electrospinning Process

Electrospinning is an interesting technique with various potential applications. CeO2 fibers production was achieved via this technique.Electrospinning is an interesting technique with various potential applications. CeO2 fibers production was achieved via this technique. In this work, the prepared condition and the fiber morphology were investigated and described. The optimum condition was 15 kV, 7 cm in distance between needle tip and ground collector, 50 wt% of i-propanol in the co-solvent. The obtained fibers were continuous with a diameter of 900 nm. The smooth electrospun fibers produced were dried for one hour, and then calcined at 450 OC for 3 hours. The calcined fibers were reduced to 600 nm and cracked on the fibers. They were ceria fibers, what verified by EDX, and XRD pattern. They had high specific surface area to volume ratio, and monolith fibers, which is applied for catalytic applications

Development of Thai Style Handmade Paper from Sugar Cane Leaves for Handicraft and Package

The objectives of this work were to develop the technique to make paper from sugar cane leaves and to make prototype handicraft and packaging products using the obtained paper. Consequently, the developed technique was transferred to the selected groups, especially the sugar cane farmers.The objectives of this work are to develop the technique of making paper from sugar cane leaves, to make the prototype products made from the developed paper, and then transfer the technology to the selected groups. The study included 5 steps: (1) select the target group of 60 people from sugar cane farmers, community enterprise group, and general public in Lopburi province, (2) make the prototype products and present to public, (3) prepare the tools for transferring the technology, (4) transfer the developed technology, and (5) evaluation and statistical analysis including frequency, percentage, mean, and standard deviation. The general information of the 60 trained people can be summarized as follows: 80.00 % is female, 26.67 % is 31-40 years old, and 40.00 % is sugar cane farmer. The objectives, content, activities, and training method were evaluated to be the best suitable. The structure of the course was found to be the most suitable. More over, the materials, training documents, and place were rated to be the most suitable to the best suitable

Tuning interactions of surface‐adsorbed species over Fe−Co/K−Al2O3 catalyst by different K contents: selective CO2 hydrogenation to light olefins

Selective CO2 hydrogenation to light olefins over Fe−Co/K−Al2O3 catalysts was enhanced by tuning bonding strengths of adsorbed species by varying the content of the K promotor. Increasing the K/Fe atomic ratio from 0 to 0.5 increased the olefins/paraffins (O/P) ratio by 25.4 times, but then slightly raised upon ascending K/Fe to 2.5. The positive effect of K addition is attributed to the strong interaction of H adsorbed with the catalyst surface caused by the electron donor from K to Fe species. Although the Fe−Co/K−Al2O3 catalyst with K/Fe=2.5 reached the highest O/P ratio of 7.6, the maximum yield of light olefins of 16.4 % was achieved by the catalyst promoted with K/Fe of 0.5. This is explained by the considerable reduction of amount of H2 adsorbed on the catalyst surface with K/Fe=2.5

Techniques for processing composites of SiC-Al2O3 and Si3N4-Al2O3

Vita.Composites of SiC - AI2O3 and SiC - mullite are unstable at high temperatures. The reactions occurring within the composites above 1700°C in stagnant inert atmospheres were characterized. Gaseous products cause excessive w eight losses which cannot be attributed to active oxidation. These losses can be successfully retarded by processing under high pressures. Compatible phases were determined by X -ray analysis and used to construct the tie tetrahedra existing at high temperatures in the Si - C - Al - O system. The reactions produced condensed phases of Al2OC and AI4O4C as well as gaseous SiO and CO. The condensed phases have high vapor pressures above 1700°C. The effect of these reactions on densification of composites by firing at different temperatures for various periods under different pressures was studied. Formed composites prepared under high pressures a t 1825°C were fired at 1700°C under normal pressure in argon, where active oxidation is expected, and in spite of the low loss in weight, deterioration in microstructure was observed. In Si3N4 - Al2O3 composites, α - Si3N4 transforms to β - Si3N4 over the investigated temperatures (above 1800°C), and β' - SiAlON and X -SiAlON were formed. Wet mixing different grain sizes, precipitating AI2O3 using different methods on dispersed SiC or Si3N4 particles, and precipitating AI2O3 on these particles and filling the voids were among the techniques studied for processing. The optimum conditions and techniques for preparing dense composites rich in alumina were established and the best microstructure and fracture toughness were obtained by coating Si3N4 particles filling the voids with AI2O3