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[en] Linear attenuation coefficients of regular as well as irregular shaped archaeological samples of FaLG (flyash-lime-gypsum) of unknown thickness have been measured employing 'simplified two media' method. Seven different liquid materials plus air have been used as media to measure attenuation coefficient of these samples. Obtained results have been compared with those for regular shaped samples. Experimental values have also been compared with theoretical values calculated from FFAST and XCOM. A good agreement has been observed between experimental and theoretical values. Present measurements employing 'simplified two media' method have been reported for the first time for checking its validation and reliability. - Highlights: → Linear attenuation coefficients were measured. → Irregular shaped FaLG archaeological samples were of unknown thickness. → Use of FaLG bricks as an eco-friendly construction material. → Simplified two media method was used and experimentally tested.
[en] The present report, drawn up at the request of the former Minister of Public Health and Environmental Affairs of the Netherlands, discusses the potential radiological consequences for the population of the Netherlands of using waste materials as building materials in housing construction. (Auth.)
[en] This paper presents some of the engineering properties of Malaysian fly ash concrete. Workability, compressive, flexural, tensile splitting, drying shrinkage, elastic modulus and non destructive tests were performed on fly ash and control OPC concrete specimens. Data show that concrete containing 25% fly ash replacement of cement exhibit superior or similar engineering properties to that normal concrete without fly ash. These encouraging results demonstrated the technical merits of incorporating fly ash in concrete and should pave the way for wide scale use of this versatile material in the Malaysian construction industry. (author)
[en] Recent results obtained by instrumental neutron activation analysis (INAA) at UJV and the techniques used in analyzing coal fly ash and aerosols are summed up. A complex INAA procedure including both long-term and short-term irradiation allows determining more than 30 elements in such samples. Thus, fly ash can be distinguished emitted by brown coal-fired power plants from that emitted by large sources firing mazout; fly ash can even be differentiated from power plants burning brown coal of different origin. In analyzing aerosols, thanks to their reliability the INAA results for background aerosols are very important for the definition of pollution of large territorial areas in Czechoslovakia. (author)
[en] Coal as the fossil fuel contains naturally occurring radionuclides and belongs to NORM (Naturally Occurring Radioactive Materials). On the other hand, slag and fly-ash belong to TENORM (Technically Enhanced Naturally Occurring Radioactive Material), and if they are released into the environment an increase and/or redistribution of natural radionuclide content can occur. For the purposes of this study, six sets of samples (18 in total) of TPP Kolubara, slag and fly-ash were collected during the periodical emission tests in May 2012th at steam boilers K3 and K4 of TPP Kolubara, Serbia. Coal, slag and fly-ash samples were prepared for analysis (milled, dried, sieved and weighed) by appropriate standard methods. Prepared samples were placed in 125 mL PVC cylindrical boxes, weighted and sealed with natural wax. Sealed samples were measured with a semiconductor HPGe spectrometer (37 percent relative efficiency) after the radioactive equilibrium was reached. The obtained values of specific activity for coal (Ac), slag (As) and fly - ash (Af) do not differ significantly compared to the values available in the literature. Analysis of determined mutual ratios As/Ac and Af/Ac are consistent, taking into account uncertainties of activity concentrations, with values of approximately 2 and 4, for K3, and 1.5 and 4, for K4. Discrepancies were noted only for 40K (both steam boilers) of As/Ac. Results indicate that further investigation with more samples should be undertaken, and also correlation between radiological and proximate analysis should be determined. (author).
[en] This study is principally concerned with characterizing the organic part of coal combustion fly ashes. High carbon fly ashes are becoming more common as by-products of low-NOx combustion technology, and there is need to learn more about this fraction of the fly ash. The project team consists of two universities, Brown and Princeton, and an electrical utility, New England Power. A sample suite of over fifty fly ashes has been gathered from utilities across the United States, and includes ashes from a coals ranging in rank from bituminous to lignite. The characterizations of these ashes include standard tests (LOI, Foam Index), as well as more detailed characterizations of their surface areas, porosity, extractability and adsorption behavior. The ultimate goal is, by better characterizing the material, to enable broadening the range of applications for coal fly ash re-use beyond the current main market as a pozzolanic agent for concretes. The potential for high carbon-content fly ashes to substitute for activated carbons is receiving particular attention. The work performed to date has already revealed how very different the surfaces of different ashes produced by the same utility can be, with respect to polarity of the residual carbon. This can help explain the large variations in acceptability of these ashes as concrete additives
[en] The mini-slump test is a fast, inexpensive and widely adopted method for evaluating the workability of fresh cementitious pastes. However, this method lacks a standardised procedure for its experimental implementation, which is crucial to guarantee reproducibility and reliability of the test results. This study investigates and proposes a guideline procedure for mini-slump testing, focusing on the influence of key experimental (mixing and testing) parameters on the statistical performance of the results. The importance of preparation of always testing at the same time after mixing, testing each batch once rather than conducting multiple tests on a single batch of material, is highlighted. A set of alkali-activated fly ash-slag pastes, spanning from 1 to 75 Pa yield stresses, were used to validate the test method, by comparison of calculated yield stresses with the results obtained using a conventional vane viscometer. The proposed experimental procedure for mini-slump testing produces highly reproducible results, and the yield stress calculated from mini-slump values correlate very well with those measured by viscometer, in the case of fresh paste of pure shear flow. Mini-slump testing is a reliable method that can be utilised for the assessment of workability of cements.
[en] Highlights: • The mullitization increased with increasing the boehmite addition. • The mullite phase firstly increased and then decreased above 1200 °C. • The optimal mullitization was achieved at 1200 °C with 12% boehmite. • The mullite powder consisted of prismatic and isotropic crystallites. • The evolution of different crystal phases was analyzed in detail.