Search Results
. Fly Ash (FA) characteristically contains small carbon-burned fragments and has many practices. In several countries, FA, which is produced when coal is burned in power plants, is a major environmental and economic problem. It is an extremely popular
utilizes alkali activators and supplementary materials like fly ash, silica fume, steel slag, and GGBS [ 6–9 ]. The hardened paste has been generated and improves the strength and durability in AAC, by the chemical reaction between a solid alumina silicate
United Nations report, the term “sustainable development” is a development that can meet the needs of the present so that the ability of future generations to meet their needs cannot be compromised [ 19 ]. Spherical particles of fly ash, due to the ball
) based admixtures. A common procedure was followed in the majority of these studies where beams prepared with SCC, frequently comprising fly ash or silica fume powders, were compared with control beams cast using vibrated concrete mixes made with
Abstract
The paper presents research results on dehydration properties and thermal behaviour of zeolites synthesized from fly ash, applying TG (thermogravimetry), DTG (derivative thermogravimetry) and SDTA (simultaneous differential thermal analysis) methods. In result of the analysis conducted water contents in zeolite samples were defined. On the basis of the data obtained from the thermogravimetric analysis, thermal behaviour of zeolites was assessed.
(Gr), silica (SiO2), E-glass fibre, boron carbide (B4C), tungsten carbide (WC), granite dust, and fly ash have all been described as reinforcement materials for Al6061-based hybrid metal matrix composites, according to the literature. In comparison to
Abstract
This paper analyzes the effect of fly ash chemical character on early Portland cement hydration and the possible adverse effects generated by the addition of gypsum. Behaviour was analyzed for pure Portland cements with varying mineralogical compositions and two types of fly ash, likewise differing in chemical composition, which were previously characterized under sulphate attack as: silicic-ferric-aluminic or aluminic-silicic ash in chemical character, irrespective if they are in nature, siliceous or siliceous and aluminous materials according to the ASTM C 618-94a. The experimental results showed that water demand for paste with a normal consistency increased with the replacement ratio in fly ash with a more aluminic than silicic chemical character, whereas it declined when silicic-ferric-aluminic ash was used. On the other hand, the differences between the total heat of hydration released at the first valley and the second peak also clearly differentiated the two types of ash. While the relative differences increased in the more aluminic than silicic ash, they declined in the more silicic than aluminic. In another vein, the findings indicate that within a comparable Blaine fineness range, the reactive alumina (Al2O3 r−) content in pozzolanic additions has a greater effect on mortar strength than the reactive silica (SiO2 r−) content, at least in early ages up to 28 days. Finally, the adverse effect generated in the presence of excess gypsum is due primarily to the chemical interaction between the gypsum and the C3A in the Portland cement and the reactive alumina (Al2O3 r−) in the fly ash.
1 Introduction Research studies are carried out by utilizing waste materials and industrial by-products such as fly ash, waste water sludge ash, municipal solid waste, etc., in the manufacturing of bricks [ 1
Abstract
Fly ash is the ash precipitated from the exhaust fumes of coal-fired power stations. It consists mainly of active silica and alumina, with large amounts of glass. The aim of this work was to study the pozzolanic activity of fly ash with lime by means of DTA as a function of the lime content and the curing time. The curves revealed that the rate of hydration, as indicated by the residual lime and hydrated compounds, increases with increasing lime content and curing time. It is concluded that fly ash can be used as a blending material in pozzolanic cement.
Abstract
Improved thermoanalytical methods have been developed that are capable of quantitative identification of various components of fly ash from a laboratory-scale fluidized bed combustion system. The thermogravimetric procedure developed can determine quantities of H2O, Ca(OH)2, CaCO3, CaSO4 and carbonaceous matter in fly ash with accuracy comparable to more time-consuming ASTM methods. This procedure is a modification of the Mikhail-Turcotte methods that can accurately analyze bed ash, with higher accuracy regarding the greater amount of carbonaceous matter in fly ash. In addition, in conjunction with FTIR and SEM/EDS analyses, the reduction mechanism of CaSO4 as CaSO4+4H2 ↔ CaS + 4H2O has been confirmed in this study. This mechanism is important in analyzing and evaluating sulfur capture in fluidized-bed combustion systems.
