Aggregates and Binders for Expendable Molds

Emissions generated when molten steel was poured into sand molds fabricated with eight different binder systems were collected separately and tested for mutagenic activity using the Ames Salmonella assay. The sampling device consisted of an initial 8 X 10 in. glass fiber filter in a custom fabricated apparatus through which air was drawn using a Hi-Vol motor and fan. A portion of the airstream, which passed this filter, was in turn passed through a smaller glass fiber filter and then into two glass impingers filled with ice-cold methanol. All the binder systems generated material, which induced mutations in the absence of added S-9 extract, and in all emissions a higher level of activity was found when S-9 was added. In the presence of S-9, the shell-core system produced by far the most mutagenic activity followed by the oil-clay-cereal system. The green sand, furan and Kold Set systems produced much lower levels while the two reclaimed sand systems and sodium silicate system were intermediate.

100% cotton plain-weaved woven fabric has been treated with inorganic effect pigment-binder system in water following solgel process. Thickener has been added to maintain the viscosity of the sol. Dispersing agent has been included where necessary to even distribution of sol on textile. Complete process was done ensuring inorganic chemicals such as pigment, binder, thickener and dispersing agent. After drying, the reflection and transmission characteristics were measured using spectrophotometry. It gives the quantitative measurements (wavelength 220 nm to 1400 nm) of the reflection and transmission properties of the coating as a function of wavelength. These values are then used to discuss the developed optical protection (against IR, visual and UV light) of coated cotton textile by inorganic effect pigment and binder system.

The ever-increasing need of infrastructure around the globe gave rise to consumption of concrete ingredients at faster pace and generates huge quantum of the construction and demolishing waste. Both factors are serious problem to environment and waste management. Therefore, this research article presents the laboratory investigation on the effect of type of fine aggregates in recycled aggregate concrete prepared with recycled aggregates from demolished concrete. It will not only reduce the waste management to some extent, help in preserving the environment, avoid health problems of inhabitants, but also help in preserving the conventional sources of aggregates. Three types of fine aggregates, i.e. river sand, pit sand and hill sand are used. The concrete using 1:2:4 mix and 0.5 water cement ratio is designed in two groups. First group used only conventional aggregates whereas, in second group 50% recycled aggregates from demolished concrete are used. In each group three batches using river sand, pit sand and hill sand are used. Slump test of each batch is conducted. In each batch 5 cylinders of standard size are prepared, cured for 28-days and tested for compressive strength. Obtained results showed better performance of conventional concrete with river sand but the induction of recycled aggregates affected both workability and compressive strength. The workability of recycled aggregate concrete with river sand was better (-14%) compared to concrete with hill sand (-20%). However, slump values for all batches remained within limits specified for normal concrete. Use of hill sand in recycled aggregate concrete showed better performance in terms of compressive strength as the residual compressive strength was recorded equal to 86% in comparison to conventional concrete with river sand. Keywords: Recycled aggregate concrete, workability, compressive strength, type of sand, fine aggregates, demolishing waste, green concrete..

Green sand reclamation using a fluidized bed with an attrition nozzle

Development of inorganic binder systems to minimise emissions in ferrous foundries

Associated with every programming language is a style of programming which is encouraged by the semantic and syntactic features of this language. We are all familiar with the phenomenon of a FORTRAN programmer approaching APL for the first time and writing correct APL programs which are nevertheless emphatically criticized for not displaying the proper APL style. Indeed we may consider this 'APL style' to be the most important contribution of the language to the art of programming, rather than the specific language features out of which this style emerges. Controversies about the value of APL (and other programming languages) focus precisely around this issue of style. It is also around this issue that we want to center our presentation of SETL.Briefly stated, SETL is a very-high level programming language whose basic semantic constructs are those of the mathematical theory of sets. Primitive operations in SETL include set membership, union, intersection, power set construction, etc. SETL provides two basic aggregate data types : unordered sets, and sequences, or tuples. The elements of sets and the components of tuples can themselves be of arbitrary type, including sets and tuples. In particular, sets of pairs (i.e. tuples of length 2) can be used as maps with perfectly general domain and range types.

The coefficient of thermal expansion (CTE) is one of the most critical parameters for concrete pavement design. Concrete paving mixtures with high CTEs are generally subjected to temperature-related stresses and deterioration. In this study, a 2k design of experiment was applied to evaluate the effects of concrete mix design variables on the CTE of resultant concrete mixtures. Laboratory experiments were conducted by controlling six mix design variables, each at two levels, including aggregate type (granite or dolomite), fine sand type (manufactured or natural), fly ash type (Class C or Class F), cement content (314 or 273 kg/m 3), coarse aggregate content (1246 or 682 kg/m 3), and air content (3% or 6%). The respective and collective effects of these factors on the CTE were analysed. It showed that the type of coarse aggregate, fine sand, fly ash, and their respective contents are significant in explaining the variance of the lab-measured CTEs. The minimum CTE is a result of the concrete mixture consisting of low content of granite and cement in combination with high content of manufactured sand and Class F fly ash. To generalise the results, a parsimonious model was formulated and is capable of explaining over 92% of the total variance of the CTE and predicting it in a reasonably accurate manner.

On the basis of the calculated Gibbs energy change for the standard state, the possibility of carbon tetrafluoride, silicon tetraftuoride, dichlorodifluoromethane and sulfur hexafluoride reacting with a number of elements and their compounds was evaluated. The reactions were studied by differential thermal analysis. Fluorination reactions of metals and oxides with dichlorodifluoride were investigated, and the temperature conditions of the syntheses were determined by measuring the "temperature at the start of interaction" (t~i.). The existence of a correlation between ts.i. and AHformatio n for the fluorinating agents was assumed, and a sequence of the fluorinating power of the non-metal fluorides was established. The perspectives of using non metal fluorides in the synthesis of inorganic fluorides are discussed. One of the most important problems in inorganic synthesis is the correct choice of the reagent. This problem is particularly important when choosing the fluorinating agent for the synthesis of inorganic fluorides, compounds finding broad fields of application in widely differing braches of technology. At present a large number of fluorinating agents used in inorganic synthesis are known [1 - 13], among them elemental fluorine [1 - 3], halogen fluorides [4- 6] and hydrogen fluoride [8], the latter in the gaseous and liquid states, as well as in the form of aqueous solutions, being the most widespread in application. The major advantage of these fluorinating agents consists in their extraordinary chemical activity, allowing them to convert practically ally compound into fluoride. However, this high chemical activity causes great difficulties in the carrying out of the process in practice. On the other hand, the use of fluorine or halogen fluorides leads to exhaustive fluorination, and hence does not allow one to obtain fluorides with lower oxidation stages. It therefore appears desirable to use as fluorinating agents fluorides of nonmetals, such as boron trifluoride, carbon tetrafluoride (and its derivatives), silicon tetrafluoride, nitrogen trifluoride, sulfur tetrafluoride and sulfur hexafluoride. Their use would substantially simplify equipment requirements for the synthesis, since the fluorides of boron, carbon (and its derivatives, freons), silicon, nitrogen and sulfur are inert under normal conditions. In addition, the fluorides of carbon, nitrogen and sulfur (the hexafluoride) are non-toxic, while the fluorides of boron,

Despite local and national road authorities striving to provide motorists with a durable and safe infrastructure environment, one in six UK roads are currently classed as being in poor condition. In terms of safety, Department for Transport statistics report high numbers of road incidents; 29,711 killed or seriously injured in 2023, representing little change compared to 2022. As such, reported in this paper is research aimed at developing artificial geopolymer cement mortar-based aggregate as a cost/environmentally attractive alternative to calcined bauxite for high friction surfacing applications. Work was undertaken in two distinct phases. In the first, the performance of alkali silicate-based geopolymers comprising a range of industrial wastes as binder materials was assessed using modified versions of standardized polished stone value and micro-Deval tests. In phase two, selected mixes were assessed for resistance to simulated wear by exposing test specimens to 20,000-wheel passes on an accelerated road test machine. Performance was further investigated using a dynamic friction test method developed by the Indiana Department of Transportation. Despite commercially sourced calcined bauxite aggregates exhibiting the highest performance levels, the findings from this preliminary research were generally positive, with acceptable levels of performance noted for manufactured geopolymer-based aggregates. For instance, in accordance with recommended levels of performance prescribed in BBA/HAPPAS standards, this included attainment of polished stone values higher than 65 and, following accelerated road testing, average texture depths greater than 1.1 mm. It is recognized that further research is needed to investigate geopolymer binder systems and blends of aggregate types, as well as artificial aggregate manufacturing procedures.

In this paper an attempt has been made for linear and non linear modeling of resin bonded sand mould system using full factorial design of experiments and response surface methodology, respectively. It is important to note that the quality of castings produced using the resin bonded sand mould system depends largely on properties of moulds, which are influenced by the characteristics of sand, like type of sand, grain fineness number, grain size distribution and quantity and type of resin, catalyst, curing time etc. In the present study, percentage of resin, percentage of hardener, number of strokes and curing time are considered as input parameters and the mould properties, such as compression strength, shear strength, tensile strength and permeability are treated as responses. In the present work, phenol formaldehyde is used as the resin whereas tetrahydrophthalic anhydride as the hardener. A two level full factorial and three level central composite designs are utilized to develop input-output relationships. Surface plots and main effects plots are used to study the effects of amount of resign, amount of hardener, number of strokes and curing time on the responses, namely, compression strength, tensile strength, shear strength and permeability. Moreover, the adequacies of the developed models have been tested using analysis of variance. The prediction accuracy of the developed models have been tested with the help of twenty test cases and found reasonably good accuracy.

Magnesium alloys, due to their low density and excellent specific strength, are known as advanced materials for ultra light and low energy consumption purposes. The present study is to investigate the effect of using different covering flux compositions on mould-metal reaction during in-situ melting of AZ91D magnesium alloy. In this study the alloy in the form of granules was charged into a ceramic shell mould and heated up under argon atmosphere and the covering fluxes to different temperatures until it was melted and filled the mould at the possible lowest temperature. Thermal analysis was used to explore the melting behavior of the granules during using in-situ melting technique. Results showed that employing covering flux is necessary to approach to a lower temperature for melting. In addition, it diminished the mould metal reaction which led to a higher quality casting surface. Moreover, the granules showed the characteristic temperatures similar to the bulk material melting. Post publication note (26 July 2012): The order of the authors has been updated and an affiliation has been added.

Towuti Lake, one of the ancient lakes in Indonesia, is the second largest freshwater lake after Lake Toba. One of the endemic fish that live in Lake Towuti is the Matano Medaka fish (Oryzias matanensis Aurich, 1935). Due to land change, Lake Towuti's indicate is in threat of declining, which potentially have an impact on the endemic fish's habitat. The aim of this study is to identify the habitat characteristics of Lake Towuti. The data collected in this study includes temperature, pH, dissolved oxygen, and aquatic plants. Sampling was carried out in the morning, starting at 8:00 WITA and ending at 11:00 WITA at two different stations. Station selection was carried out based on differences in habitat, the presence of aquatic plants, and the presence of fish samples. Habitat characteristics at station one are marked by the number of water plants with the basic substrate types of sand, mud, and stones. In contrast, at station two, it is characterized by the absence of water plants and the basic substrate types of sand, rock, and gravel. Ecological aspects, including water physics and chemistry parameters, did not experience large fluctuations during the study period. The water conditions at each research station were not significantly different, so the water conditions were still good and supported the fish life in Lake Towuti.

Depletion of high-quality natural sand deposits and sustainability concerns are popularizing manufactured sand use in cementitious composites. Meanwhile, palm fruit bunch fiber (PFBF) improves the properties of cementitious composites, but it is unclear how PFBF interacts with different fine aggregates to affect mortar strength. This study investigated the impact of PFBF on the compressive strength of cement mortars containing manufactured sand (granite quar- ry dust) and natural sands (river and pit). The aggregates were used with Portland cement to fabricate mortar cubes, which were tested after 28 days. The control mortars (0% PFBF) of quarry dust, river sand, and pit sand recorded strength of 24.2 MPa, 21.5 MPa, and 10.4 MPa, respectively. At the optimum fiber content, the strength of the quarry dust and pit sand mor- tars increased marginally to 24.7 MPa and 12.2 MPa, respectively. However, river sand mortar strength considerably increased to 26.1 MPa. Interestingly, the quarry dust and pit sand mortars generally experienced strength loss before reaching their peak at 2.0% and 2.5% fiber content, respectively. In comparison, river sand mortar consistently gained strength before peaking at 2.5% PFBF. Hence, pre-optimum fiber contents could enhance river sand mortar strength but hinder quarry dust and pit sand mortar strengths. By standardizing the PFBF-reinforced mortar strengths against the control strengths, PFBF enhanced pit sand mortar strength the most, fol- lowed by river sand mortar, but it mainly reduced quarry dust mortar strength. Mortar design must, therefore, optimize PFBF dosage considering the unique characteristics of each sand type.