Papers by Keyword: Slag

Abstract: Production of Ordinary Portland Cement (OPC) requires huge quantity of natural resources and energy and it releases large amount of carbon - di - oxide to the environment. Therefore, enormous studies have been carried out throughout the world to establish geopolymer as an alternative binder material for the replacement of OPC to protect the environment. This study intends to explore the effects of alkaline solution on the properties of geopolymer produced with ground granulated blast furnace slag. Properties such as Standard consistency, setting time of slag based geopolymer paste has been determined using Vicat’s apparatus (according to the guidelines given by Indian Standards for OPC). In order to determine the effects of alkaline solution on the properties of geopolymers, the concentration of sodium hydroxide solution has been varied from 6M to 16M and the ratio of sodium silicate solution to sodium hydroxide solution is also varied from 1.0 to 2.0. Results indicate higher standard consistency and significant less setting time for slag based geopolymer paste than that of OPC paste. Compressive strength of the geopolymer paste and mortar cube samples, cured in ambient conditions till the day of testing, is increasing with the increase of the concentration of sodium hydroxide solution. Highest compressive strength is obtained for the samples prepared with alkaline solution having the ratio of sodium silicate solution to sodium hydroxide solution as 1.5. But when the concentration of sodium hydroxide solution is beyond 14M, decreasing trend in compressive strength is observed.

Abstract: The alkali-activated slag is an alternative building material to ordinary Portland cement based materials. This type of material is effective in reducing CO₂ emissions and energy consumption. Addition of graphite powder increases its electric conductivity, hence, introducing new functionality to building materials such as self-sensing and self-heating properties. In this study, the effect of graphite filler on the crack initiation of alkali-activated slag composite is investigated. The graphite powder was added in the amount of 5, 10 and 15% with respect to the slag mass. Beam specimens with an initial stress concentrator were tested in three-point bending at the age of 28 days. The load versus crack mouth crack opening displacement (F–CMOD) diagrams were recorded during the fracture tests and subsequently evaluated using the Double-K fracture model. This model allows the quantification of two different levels of crack propagation: initiation, which corresponds to the beginning of stable crack growth, and the level of unstable crack propagation. The course of fracture tests was also monitored by acoustic emission (AE) method.

Abstract: Building materials with enhanced electrical properties gain the importance in the new field of applications such as self-sensing or self-heating materials. In this paper, 3 mm long carbon fibres were used as a conductive admixture to alkali-activated slag mortar in order to reduce its resistivity. The amount of carbon fibres was ranging from 0.5 to 4.0% of the slag mass and the effect of the conductive admixture on the mechanical properties, electrical impedance, specific conductivity, and microstructure of alkali-activated slag composite was investigated. Only 0.5% of carbon fibres caused a significant decrease in impedance of alkali-activated slag composite and the addition of 4% reduced the impedance by one order of magnitude for low AC frequencies. However, due to problematic dispersion and higher demand of mixing water, the mechanical properties were deteriorated, especially at higher content of carbon fibres.

Abstract: Three tasks have been consistently solved in this paper. A thermodynamic analysis of the high-carbon ferromanganese smelting was carried out. The associated solutions theory was used to describe a thermodynamic activity of components in the metal and slag. Comparison of the calculated and technological data shows that the melting ends in conditions close to chemical equilibrium. The mineral phases in the slag, the relative amount and chemical composition of the phases are determined by X-ray diffraction analysis and X-ray spectral microanalysis. The method of converting the phase volume fraction to phase mass fraction (without using weight density) was suggested. It is established that there is no unambiguous relationship between the total content of MnO by chemical analysis and the MnO content in slag oxide phases. Also, there is no correspondence between the total content of MnO by chemical analysis and the amount of ferromanganese inclusions in the slag. A calculation-experimental method for description of manganese losses in the slag has been created. Correlation equations allow calculating the manganese distribution between the ferromanganese inclusions and slag phases by chemical analysis data only, without microscopic analysis of the structure.

Abstract: Studied the effect of the introduction of vanadium and cobalt into the charge powder fused wire system Fe-C-Si-Mn-Cr-Ni-Mo-V, used in cladding assemblies and equipment parts and mechanisms operating under abrasive and abrasive shock loads. the cored wires samples were manufactured in the laboratory conditions and using appropriate powder materials and as a carbonfluoride contained material were used the dust from gas purification of aluminum production.

Abstract: In recent years, sustainability and environmental effect of concrete became the main concern. Substituting cement with the other cementitious material without decreasing mechanical properties of a mixture could save energy, reduce greenhouse effect due to mining, calcination and limestone refining. Therefore, some industrial by-products such as fly ash, silica fume, and Ground Iron Blast Furnace Slag (GIBFS) would be used in this study to substitute cement and aggregate. This substitution would be applied on the porous concrete mixture to minimize the environmental effect. Slag performance will be optimized by trying out variations of fly ash, silica fume, and slag as cement substitution material in mortar mixture. The result is narrowed into two types of substitution. First, reviewed from the fly ash substitution effect on binder material, highest compressive strength 16.2 MPa was obtained from mixture composition 6% fly ash, 3% silica fume and 17% grinding granular blast-furnace slag. Second, reviewed from slag types as cement substitution and silica fume substitution, highest compressive strength 15.2 MPa was obtained from mortar specimens with air-cooled blast furnace slag. It composed with binder material 56% Portland composite cement, 15% fly ash, 3% silica fume and 26% air-cooled blast furnace slag. Considering the cement substitution, the latter mixture was chosen.

Abstract: Hybrid cements represent a relatively new type of binders which combines some of the advantages of Ordinary Portland Cement and an application of mineral admixtures and alkali activation. Hybrid cements form then blends containing a low portion of OPC and a high proportion of mineral additions (such as blast furnace flag, fly ash, metakaoline, ...). This paper discusses the properties of mortars based on carbonate based activators. Mixtures composed from Ordinary Portland Cement, ground granulated blast furnace slag, fly ash and mechanically pre-activated fly ash were optimised with the target to achieve sufficient compressive strength. The influence of ratios between powder compounds, the dosage of activator and water to binder ratios are presented.

Abstract: During the Bronze Age intensive mining and smelting activities for copper production took place in the Eastern Alps. To get information about the copper smelting process, the elemental compositions of slags are marked in equilibrium phase diagrams (e.g. FeO-CaO-SiO₂) and so the melting properties can be estimated. Doing so you have to keep in mind that slags have complex compositions and phase diagrams are available for three compounds only. For the analytical measurements it has to be ensured that only molten parts of the slag are measured and not contamination of other ambient material. Spot and area measurements by SEM-EDX are useful to get realistic data. In this case a complete correlation between the image of the analyzed area, the microstructure and the chemical composition of the sample is necessary. For marking spots in the phase diagram the calculation method has to be described exactly. For our results we calculated the ratio FeO-SiO₂-CaO(+MgO+Al₂O₃). From the morphology of the observed phases, their chemical composition and the data from the phase diagram a solidification sequence can be suggested. We recommend this method because measurements by e.g. XRF provide rather general composition values. If the slag samples are inhomogeneous, unrealistic melting points are read from the phase diagram. Inhomogeneities can be caused by soil contaminations, which are not part of the molten slag, or by corrosion, when some phases were attacked and changed during storage in soil.

Abstract: Carbon dioxide (CO₂) is one of the greenhouse gases (GHG) and the concentration is much more higher than other GHG gases. Based on the prediction, about 285.73 million tonnes will be emitted in year 2020 with the main contributors are from power generation, manufacturing industries, transportation and residential sector [1]. This research focused to study the effect of pressure on the CO₂ absorption with Malaysia steel slag using mechanical stirrer. The steel slag is collected from one of steel industry located in Pasir Gudang Johor Malaysia and characterized to investigated the chemical composition. The reaction between CO₂ absorption and the slag was investigated by using different speed and weight. The initial pressure was set at 101.3 kPa which equivalent with 1 atmospheric pressure. The behavior of the reaction between CO_2, and ground sample was investigated by measuring the change in the CO₂ pressure inside the mechanical stirrer. It was found that the CO₂ pressure decreased as soon as the stirrer started and continuously decreased till bout 270 t/min stirring time.

Abstract: The geopolymeric materials present a viable alternative as concretes, the durability of these materials is associated to expected environmental conditions and one of the problems is their corrosion. The objective of this study was to assess the durability of geopolymeric materials through the chemical attack by sulfuric and hydrochloric acids with 5% concentration. After synthesis of the geopolymeric materials, followed by curing at room temperature for 28 days and then the geopolymeric materials were subjected to cycles of chemical attacks, which consisted of periods of seven days of immersion and seven days of drying at room temperature, four cycles were provided. The geopolymeric materials were characterized and it was found that they exhibit adequate resistance to chemical attack, the adequate strength consisted of determining the mass loss in each cycle attack.