Filtreler
Durability of concrete incorporating non-ground blast furnace slag and bottom ash as fine aggregate

Yüksel I. | Bilir T. | Özkan O.

Article | 2007 | Building and Environment42 ( 7 ) , pp.2651 - 2659

The paper presents investigation of how the usage of bottom ash (BA), granulated blast furnace slag (GBFS), and combination of both of these materials as fine aggregate in concrete affects the concrete durability. To assess durability characteristics of concrete, durability tests were conducted and the results were evaluated comparing with reference concrete. Three series concrete were produced. GBFS, BA and GBFS+BA are replaced the 3-7 mm-sized aggregate. Five test groups were constituted with the replacement percentages as 10%, 20%, 30%, 40% and 50% in each series. These by-products were used as non-ground form in the concrete. Du . . .rability properties of the concretes were compared in order to study the possible advantages of different replacement ratios. According to results, GBFS and BA affects some durability properties of concrete positively in case of it is used as fine aggregate. Resistance to high temperature and surface abrasion are positively affected properties. Capillarity, drying-wetting and freezing-thawing resistance of the concrete can be accepted to some extent. Properties of by-products and its replacement ratio are controlling the influence level and direction. Comparison of the SEM images and test results show that chemical and physical properties of GBFS and BA are the main factors affecting the concrete durability. It is concluded that it is possible to produce durable concrete by using GBFS and BA as fine aggregate. © 2006 Elsevier Ltd. All rights reserved Daha fazlası Daha az

Effects of coal properties on the production rate of combustion solid residue

Durgun D. | Genç, Ayten

Article | 2009 | Energy34 ( 11 ) , pp.1976 - 1979

The production rates of furnace bottom ash in a pulverized coal-fired power plant were monitored for a two-year period and its variations with respect to coal properties were analyzed. The power plant was originally designed to fire the coal sludge generated from a washing process; however, the coal sludge and its mixture with low-rank bituminous coal have been started to be used as the main fuel with time. The results of the hardgrove grindability measurements have shown that the grinding properties of sludge or its mixtures could not be predicted based on proximate analysis (moisture, ash, carbon and volatile contents); it could o . . .nly be determined by experiments. The production rate of bottom ash in this particular power plant remained relatively insensitive to the high ash and moisture contents and could be estimated almost only by knowing the calorific value of the source coal. The evaluated dependency was linear. © 2009 Elsevier Ltd. All rights reserved Daha fazlası Daha az

Prediction of the bottom ash formed in a coal-fired power plant using artificial neural networks

Bekat, Tuğçe | Erdoğan, Muharrem | İnal, Fikret | Genç, Ayten

Article | 2012 | Energy45 ( 1 ) , pp.882 - 887

The amount of bottom ash formed in a pulverized coal-fired power plant was predicted by artificial neural network modeling using one-year operating data of the plant and the properties of the coals processed. The model output was defined as the ratio of amount of bottom ash produced to amount of coal burned (Bottom ash/Coal burned). The input parameters were the moisture contents, ash contents and lower heating values of the coals. The total 653 data were divided into two groups for the training (90% of the data) and the testing (10% of the data) of the network. A three-layer, feed-forward type network architecture with back-propaga . . .tion learning was used in the modeling study. The activation function was sigmoid function. The best prediction performance was obtained for a one hidden layer network with 29 neurons. The learning rate and the tolerance value were 0.2 and 0.05, respectively. R2 (coefficient of determination) values between the actual (Bottom ash/Coal burned) ratios and the model predictions were 0.988 for the training set and 0.984 for the testing set. In addition, the sensitivity analysis indicated that the ash content of coals was the most effective parameter for the prediction of the ratio of bottom ash to coal burned. © 2012 Elsevier Ltd Daha fazlası Daha az

Usage of industrial by-products to produce plain concrete elements

Yüksel I. | Bilir T.

Article | 2007 | Construction and Building Materials21 ( 3 ) , pp.686 - 694

This paper describes the results of research aimed at studying the possible usage of bottom ash (BA) and granulated blast-furnace slag (GBFS) in production of plain concrete elements. Sufficient number of briquettes, paving blocks and kerbs specimens containing GBFS and BA as fine aggregate replacement were produced in laboratory. Then, some of tests were conducted for investigating durability and mechanical properties of these specimens. Unit weight, compression strength and freeze-thaw tests were conducted for briquette specimens. Compression strength, freeze-thaw, water absorption and surface abrasion tests were conducted for pav . . .ing blocks. Surface abrasion and flexural tensile strength tests were conducted for kerb specimens. While compression strength was decreased slightly, durability characteristics such as resistance of freeze-thaw and abrasion were improved. The results showed that usage of partially fine aggregate of these industrial by-products has more beneficial effects on durability characteristics of plain concrete elements. © 2006 Elsevier Ltd. All rights reserved Daha fazlası Daha az

Influence of high temperature on the properties of concretes made with industrial by-products as fine aggregate replacement

Yüksel S. | Siddique R. | Özkan O.

Article | 2011 | Construction and Building Materials25 ( 2 ) , pp.967 - 972

Influence of high temperature on the properties of concrete containing non-ground granulated blast-furnace slag (GBFS) and coal bottom ash (BA) as fine aggregate was presented. Six series of concrete mixtures were prepared by partially replacing fine aggregate separately with GBFS and BA. Replacement percentages were between 10 and 50% with an increment of 10% by dry weight of fine aggregate. Then 0.2% polypropylene fibres (PP) were added to last three mixtures that has the same mixture with the first three series. The first series is control concrete, the second series contained GBFS and the third series contained BA. All the concr . . .ete specimens were exposed to 800 °C temperature at the age of 90 days. Tests were conducted to determine loss in weight, compressive strength, and dynamic modulus of elasticity. Also surface crack observations were conducted with microscope. Test results showed that it is possible to partially replace fine aggregate with GBFS or BA even if such concretes were to be subjected to high temperature response. Performance of BA concrete was found to be better than GBFS as replacement material. © 2010 Elsevier Ltd. All rights reserved Daha fazlası Daha az

Production of briquette with bottom ash [Kazanalti külü i·le bri·ket üreti·mi·]

Yüksel I. | Özkan Ö. | Bilir T.

Article | 2006 | Journal of the Faculty of Engineering and Architecture of Gazi University21 ( 3 ) , pp.527 - 532

Bottom ash (BA) is a kind of solid waste from coal-fired thermal power plants. In Turkey, there is not any usage field of this waste and dumping this waste to landfills requires high costs day after day. In this study, a possible usage of bottom ash (BA) as fine aggregate in concrete briquette production was researched. The research is constituted in two stages. The first stage is the experimental investigation of natural sand replaced by BA. Concrete briquettes specimens providing TS406 were produced by replacing natural sand with BA by volume in various percentages. Unit weight, compressive strength and freeze-thaw tests were appl . . .ied on these specimens. In second stage, cost analysis, lightness and some example applications about them were made. Although, in BA-replaced briquettes, compressive strength and freeze-thaw resistance decreases, it is still possible to produce briquettes providing the minimum conditions in the related standard. Furthermore, being low-cost, environmentally friendliness and lightness are positive results Daha fazlası Daha az

Prediction of unburned carbon in bottom ash in terms of moisture content and sieve analysis of coal

Bilen M. | Kizgut S. | Akkaya B.

Article | 2015 | Fuel Processing Technology138 , pp.236 - 242

Pulverized fuel combustion should be efficient in terms of power generation, resulting in less unburned carbon (UBC) in ash. In this study, three types of samples from stockyard, coalfeeders to mills, and bottom ash (BA) were taken from a local thermal power plant for 12 days. Proximate analysis of stockyard coal (sub-bituminous) resulted as 9.57% ash, 37.14% volatile matter, 52.91% fixed carbon, and a gross calorific value of 6640 kcal/kg. Petrographic analysis of coal showed that more than 80% consisted of reactive macerals. Coal from coalfeeders was also analyzed in terms of moisture content and sieve analysis. BA samples were an . . .alyzed and UBC content of BA over a 12 day period changes between 0.49 and 0.71% for Unit 1 and 0.26 to 0.69% for Unit 2. A relationship was seen between the moisture content and size distribution of coal from the mill inlet with UBC in the BA. A modified population model was used to estimate UBC as a function of size distribution, moisture content, mill environment constant, boiler environment constant, and residence time. A population model was used because the grinding and combustion operations are similar in terms of formation of new particles. It is seen that the model proposed is in agreement with the experimental results. In conclusion, in order to lower the amount of UBC in ash, the size distribution and moisture content of feed coal to mills should be stabilized. © 2015 Elsevier B.V. All rights reserved Daha fazlası Daha az

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