Microstructural properties and pozzolanic activity of calcined kaolins as supplementary cementing materials

2012 ◽  
Vol 39 (12) ◽  
pp. 1274-1284 ◽  
Author(s):  
Erhan Güneyisi ◽  
Mehmet Gesoǧlu ◽  
Turan Özturan ◽  
Kasım Mermerdaş
Keyword(s):  
Particle Size ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Thermo Gravimetric Analysis ◽  
Particle Size Analysis ◽  
Pozzolanic Activity ◽  
Area Measurement ◽  
Size Analysis ◽  
Gravimetric Analysis

In this study, the utilization of unprocessed kaolins calcined at various temperatures as supplementary cementing material was investigated experimentally. The current work deals with four kaolin deposits existing in the western region of Turkey that have not yet been investigated for this purpose. Thermal properties of the unprocessed kaolins were examined by means of differential thermal and thermo gravimetric analysis. After determination of the thermal behavior, pozzolanic activity indices of the kaolins were determined according to ASTM C311. Based on the pozzolanic activity test results, calcination temperatures were assigned for kaolins and the changes in the mineralogical composition and the formation of amorphous structures were examined by X-ray diffraction analysis. The changes in particle size and specific surface area of the calcined kaolin minerals were observed through, particle size analysis with laser diffractometer, Scanning electron microscopy image analysis, and Brunauer-Emmett-Teller specific surface area measurement. The results showed that a complete kaolinite to metakaolinite conversion was achieved by the calcination procedure adopted.

Structure and Catalytic Soot Combustion of Perovskite La-Mn-O Hollow Microfibers via Gel-Precursor Transformation Process

2012 ◽  
Vol 538-541 ◽  
pp. 2289-2292
Author(s):  
Xiao Xiao Meng ◽  
Feng Lin He ◽  
Jiang Ying Shen ◽  
Xiang Qian Shen
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
High Surface ◽  
Thermo Gravimetric Analysis ◽  
Transformation Process ◽  
High Catalytic Activity ◽  
Gravimetric Analysis ◽  
Soot Combustion ◽  
Aspect Ratios

The nanocrystalline perovskite La-Mn-O hollow microfibers were prepared by the gel-precursor transformation process from reagents of metal salts and citric acid. The gel precursor and resultant products were characterized by Fourier transform infrared spectroscopy, X-ray diffraction and scanning electron microscopy. The specific surface area was measured by the Brunauere-Emmette-Teller method. The catalytic performance of soot combustion was evaluated by thermo-gravimetric analysis under model conditions. The nanocrystalline La-Mn-O hollow microfibers calcined at 650 °C for 6 h are characterized with diameters of 2-8 µm, aspect ratios (length/diameter) about 5-15, a micro-tunnel with an estimated ratio 1/3 of the hollow diameter to fiber diameter, and a high specific surface area of 36.7 m2/g that is 1.9 times higher than the counterpart nanosized powder. This nanocrystalline La-Mn-O hollow microfibers catalyst exhibit a high catalytic activity for the soot combustion, with a low T50 of 397°C, which is largely owing to the high surface area and the micro-tunnel structure.

scholarly journals PHYSICOCHEMICAL PROPERTIES AND POZZOLANIC PERFORMANCE OF ULTRAFINE TREATED RICE HUSK ASH (UFTRHA) AS ADDITIVE IN CONCRETE

2018 ◽  
Vol 16 ◽  
Author(s):  
Siti Asmahani Saad ◽  
Nasir Shafiq ◽  
Maisarah Ali
Keyword(s):  
Particle Size ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Rice Husk ◽  
Amorphous Silica ◽  
Rice Husk Ash ◽  
High Energy ◽  
Size Analysis ◽  
Pre Treatment

Rice husk ash (RHA) contains high amount of amorphous silica that is ubiquitous in the pozzolanic reaction of SCM in concrete. However, usage of conventional RHA is currently unfavourable in concrete industry due to its properties inconsistency. In this regard, improvement on the RHA properties by introduction of thermochemical pre-treatment prior to burning procedure is seen as an excellent way to reach the goal. In this paper, raw rice husk was pre-treated using 0.1N hydrochloric acid (HCl) and heated at 80oC. It was then mechanically activated by high energy planetary ball mill for 15 minutes at speed of 300rpmand ball-to-powder ratio (BPR) of 15:1. The chemical composition, mineralogical properties, particle size analysis, specific surface area as well as microstructure properties of ultrafine treated rice husk ash (UFTRHA) were determined accordingly. As for amorphous silica content of the optimum sample was recorded as 98.60% incinerated at 600oC with four hours of pre-treatment soaking duration. In terms of particle size and specific surface, it was also observed that, burning temperature of 600oC, pre-treated at four hours were recorded to produce finest size of UFTRHA where d(0.1), d(0.5) and d(0.9) were obtained as 1.416?m, 4.364 ?m and 14.043 ?m respectively. Largest specific surface area value was obtained at 219.58 m2/g with the similar pre-treatment conditions. Meanwhile, the strength activity of UFTRHA from the optimum pre-treatment process was measured by testing the compressive strength of mortars. The highest compression value obtained was 50.17MPa with 3% UFTRHA replacement at 28 days.

Mechanisms on formation of hierarchically porous carbon and its adsorption behaviors

2016 ◽  
Vol 74 (1) ◽  
pp. 266-275 ◽  
Author(s):  
Jie Liu ◽  
Lingxia Hao ◽  
Wenzhen Qian ◽  
Yu-Feng He ◽  
Rong-Min Wang
Keyword(s):  
Activated Carbon ◽  
Electron Microscope ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Photoelectron Spectroscopy ◽  
Thermo Gravimetric Analysis ◽  
Gravimetric Analysis ◽  
Hierarchically Porous ◽  
Adsorption Behaviors

Using simple one-step carbonization-activation, the residues of paulownia flowers are employed as a precursor to prepare hierarchically porous activated carbon. After investigating the optimum conditions, the obtained paulownia flowers based activated carbon (PFAC) is characterized by Fourier transform infrared spectroscopy, scanning electron microscope, transmission electron microscope, Brunauer–Emmett–Teller specific surface area analysis (SBET), thermo gravimetric analysis, and X-ray photoelectron spectroscopy. The PFAC owns a high specific surface area of 1,053 m2/g as well as a hierarchically porous structure with a combination of micro-, meso- and macropores. The pore-forming mechanism is discussed according to results of characterization. Using methylene blue as model dye, the adsorption behaviors of PFAC were investigated. We found that the dye could be rapidly adsorbed by hierarchically porous PFAC, and the adsorption capacity of PFAC reached 300 mg/g.

scholarly journals PHYSICOCHEMICAL PROPERTIES AND POZZOLANIC PERFORMANCE OF ULTRAFINE TREATED RICE HUSK ASH (UFTRHA) AS ADDITIVE IN CONCRETE

2018 ◽  
Vol 16 (6) ◽  
Author(s):  
Siti Asmahani Saad ◽  
Nasir Shafiq ◽  
Maisarah Ali
Keyword(s):  
Particle Size ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Rice Husk ◽  
Amorphous Silica ◽  
Rice Husk Ash ◽  
High Energy ◽  
Size Analysis ◽  
Pre Treatment

Rice husk ash (RHA) contains high amount of amorphous silica that is ubiquitous in the pozzolanic reaction of SCM in concrete. However, usage of conventional RHA is currently unfavourable in concrete industry due to its properties inconsistency. In this regard, improvement on the RHA properties by introduction of thermochemical pre-treatment prior to burning procedure is seen as an excellent way to reach the goal. In this paper, raw rice husk was pre-treated using 0.1N hydrochloric acid (HCl) and heated at 80oC. It was then mechanically activated by high energy planetary ball mill for 15 minutes at speed of 300rpmand ball-to-powder ratio (BPR) of 15:1. The chemical composition, mineralogical properties, particle size analysis, specific surface area as well as microstructure properties of ultrafine treated rice husk ash (UFTRHA) were determined accordingly. As for amorphous silica content of the optimum sample was recorded as 98.60% incinerated at 600oC with four hours of pre-treatment soaking duration. In terms of particle size and specific surface, it was also observed that, burning temperature of 600oC, pre-treated at four hours were recorded to produce finest size of UFTRHA where d(0.1), d(0.5) and d(0.9) were obtained as 1.416?m, 4.364 ?m and 14.043 ?m respectively. Largest specific surface area value was obtained at 219.58 m2/g with the similar pre-treatment conditions. Meanwhile, the strength activity of UFTRHA from the optimum pre-treatment process was measured by testing the compressive strength of mortars. The highest compression value obtained was 50.17MPa with 3% UFTRHA replacement at 28 days.

scholarly journals Synthesis and Characterization of Mn–C–CodopedTiO2Nanoparticles and Photocatalytic Degradation of Methyl Orange Dye under Sunlight Irradiation

2012 ◽  
Vol 2012 ◽  
pp. 1-7 ◽  
Author(s):  
Wei Xin ◽  
Duanwei Zhu ◽  
Guanglong Liu ◽  
Yumei Hua ◽  
Wenbing Zhou
Keyword(s):  
Particle Size ◽  
Methyl Orange ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Visible Region ◽  
High Specific Surface Area ◽  
Size Analysis ◽  
Manganese Acetate ◽  
Sunlight Irradiation

Novel visible-light-active Mn–C–TiO2nanoparticles were synthesized by modified sol-gel method based on the self-assembly technique using polyoxyethylenes orbitan monooleate (Tween 80) as template and carbon precursor and manganese acetate as manganese precursor. The samples were characterized by XRD, FTIR, UV-vis diffuse reflectance, XPS, and laser particle size analysis. The XRD results showed that Mn–C–TiO2sample exhibited anatase phase and no other crystal phase was identified. High specific surface area, small crystallite size, and small particle size distribution could be obtained by manganese and carbon codoped and Mn–C–TiO2exhibited greater red shift in absorption edge of samples in visible region than that of C–TiO2and pure TiO2. The photocatalytic activity of synthesized catalyst was evaluated by photocatalytic oxidation of methyl orange (MO) solution under the sunlight irradiation. The results showed that Mn–C–TiO2nanoparticles have higher activity than other samples under sunlight, which could be attributed to the high specific surface area, smaller particle size, and lower band gap energy.

Internal surface area and porosity of kaolinitic glaebules

Soil Research ◽  
1975 ◽  
Vol 13 (2) ◽  
pp. 235
Author(s):  
ID Sills
Keyword(s):  
Particle Size ◽  
Specific Surface ◽  
Pore Size ◽  
Surface Area ◽  
Sandy Loam ◽  
Average Pore Size ◽  
Particle Size Analysis ◽  
Size Analysis ◽  
Internal Surface Area ◽  
Pore Size Distributions

Specific surface areas, cation exchange capacities and pore size distributions have been determined on sieved fractions of a sandy loam from Merredin, W.A., certain horizons of which contain significant proportions of kaolinitic glaebules. The sand-sized glaebules are resistant to breakdown by normal dispersion techniques, and so remain in the sand fraction during particle size analysis. However, certain of their physicochemical characteristics are consistent with those of soil colloids. For instance, the 250-500 �m fraction of the 155-190 cm horizon has a specific surface area of 16.3 m2/g, an average pore size of some 6 nm plate separation and a surface charge density of 3.8 x 104 esu/cm2. In soils containing significant proportions of such glaebules, the physicochemical properties will differ markedly from those inferred from particle size analysis.

The Synthesis of Pseudoboehmite Using Factorial Experimental Design

2015 ◽  
Vol 365 ◽  
pp. 226-231 ◽  
Author(s):  
Antonio Hortêncio Munhoz ◽  
T.J. Masson ◽  
Leila Figueiredo de Miranda ◽  
A. Cabral Neto ◽  
Raphael Cons Andrades ◽  
...  
Keyword(s):  
Thermal Analysis ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Ageing Time ◽  
Sol Gel ◽  
Thermo Gravimetric Analysis ◽  
Precursor Solution ◽  
High Specific Surface Area ◽  
Gravimetric Analysis

Different samples of pseudoboehmite were synthesized through the sol-gel process, using aluminum nitrate as precursor. The influence of variables on the product of the synthesis of pseudoboehmite was studied. The variables were the ageing temperature (25 and 130°C), addition or not of polyvinyl alcohol to the precursor solution and the ageing time of the PB. The pH adjustment of the precursor solution was made by using ammonium carbonate. The pseudoboehmites, which were obtained on different conditions, were then characterized by X-ray diffraction, thermal analysis (Differential Thermal Analysis and Thermo Gravimetric Analysis) and the desorption-absorption curves were obtained as well, in order to measure the pore volume of the samples and the specific surface area measurements through the BET method. Finally, the results were analyzed through an experimental factorial planning, which showed that high specific surface area pseudoboehmite was obtained.

Influence of particle size and specific surface area on the pozzolanic activity of residual rice husk ash

2011 ◽  
Vol 33 (5) ◽  
pp. 529-534 ◽  
Author(s):  
Guilherme Chagas Cordeiro ◽  
Romildo Dias Toledo Filho ◽  
Luis Marcelo Tavares ◽  
Eduardo de Moraes Rego Fairbairn ◽  
Simone Hempel
Keyword(s):  
Particle Size ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Rice Husk ◽  
Rice Husk Ash ◽  
Pozzolanic Activity

Physical Properties Variability of Zinc Powders Obtained by Electrochemical Method

2021 ◽  
Vol 316 ◽  
pp. 689-693
Author(s):  
K.D. Naumov ◽  
V.G. Lobanov
Keyword(s):  
Particle Size ◽  
Specific Surface ◽  
Bulk Density ◽  
Surface Area ◽  
Specific Surface Area ◽  
Current Density ◽  
Zinc Concentration ◽  
Regulatory Change ◽  
Average Particle ◽  
Zinc Powders

The aim of this paper is to establish a regulatory change of zinc powders key physicochemical properties with varying electroextraction conditions. It was studied influence zinc concentration, alkali concentration and current density. Quantitative dependencies of zinc powders particle size and specific surface area from mentioned electroextraction parameters are shown. At increasing of zinc concentration, decreasing of NaOH concentration and decreasing of current density of powders particle size growth, correspondingly specific surface area is declined. It is indicated, that electrolytic zinc powders bulk density varies from 0.61 g/cm3 to 0.75 g/cm3 with a decrease of average particle size from 121 μm to 68 μm. In comparison, spherical powders bulk density used in various industries is currently 2.45-2.6 g/cm3. In all experiments, metal zinc content varied in the range of 91.1-92.5%, the rest - ZnO. To a greater extent, this indicator depends on powder washing quality from alkali and storage conditions.

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