Key Engineering Materials Vol. 663

Abstract: The industrial activities are responsible for the production of large amounts of solid wastes, which, so far, have found scarce reuse alternative. Clay-based materials show a natural forgiveness towards the incorporation of a wide variety of wastes. This study reported the changes in technological properties of clay-based mixture normally used in the production of bricks, due to the additions of a spent diatomite earth (SDE) discarded by the beer filtration process in the brewing industry. Samples containing 0-10 wt % SDE were extruded and sintered in air in an electric furnace (950 °C, for 3 h). SDE thanks to their organic substances content, during their combustion, act as pore forming agent and providing an energy support in the brick firing process. Also, the waste, because of its high silica content can act as a silica carrier. The results obtained showed that SDE, added in a percentage of 3 wt % to a brick formulation, had better influence with respect to control bricks containing only clay, improves the mechanical properties (compressive strength around 45 MPa) with a bulk density reduction of about of 2%. However, the incorporation of waste in percentage of 7 and 10 wt % had a negative effect due to increased porosity fundamentally open pores generated in the clay body by the combustion of SDE waste, leading to water suction, water absorption and compressive strength values that do not fall within the range specified by bricks UNE standards. Therefore, SDE can thus advantageously used in lower amounts (3 wt %) as silica carrier and in lower proportion as pore agent in clay bricks, with the potential to reduce fuel and natural ceramic raw material consumption, as well as, landfill costs.

Abstract: This work evaluates some preliminary results of adding two kinds of wastes in two characteristics clay mixtures with the aim of producing lighter structural ceramic products. The selected wastes are marble cutting dust and a packaging waste mainly composed by paperboard and polyethylene. In the case of clay mixtures, they are focused to the manufacture of both common and facing bricks. New waste based formulations are proposed on the basis of chemical and mineralogical compositions of clays and wastes and previous experiences in literature. Especial attention is paid to initial carbonate content in the selected clays, since marble waste is almost exclusively formed by calcite. Dynamic sintering tests and technological properties characterization were performed to analyse the feasibility of waste incorporation. Sintering behaviour shows a larger influence of marble dust waste and it is radically changed in the case of clay mixtures for facing products. Technology properties of unfired specimens are in general adequate for the industrial practice. Final technological properties of sintered specimens shows lower density for the new waste bearing products but not unique trends with sintering temperature for another properties as bending strength or water absorption capacity. These properties are mainly conditioned by the sintering behaviour associated to marble dust addition and, thus additional microstructure and mineralogy test would be necessary for a better knowledge of these materials and their optimised formulation.

Abstract: Fiber concretes have been revolutionizing the market, as well as lower operating costs, structurally act. The total or partial replacement of steel with natural fiber reinforced concrete could be an economical way to provide an alternative method to achieve greater security in concrete structures, as well as a way to use materials that are energy efficient, economic and ecological.Sisal fiber reinforcement is promising for use in composite materials, due to their low cost, low density, high strength and specific modulus, without risk to health, readily available in some countries and renewal.We studied four different dosages of concrete: without fiber, with two different types of polypropylene (PP) fibers and with sisal fiber. Consistency of fresh concrete, bulk density, water absorption, capillary absorption, compressive strength and microstructural properties values of the samples were investigated.Regarding the consistency of fresh concrete, measured by testing Abrams cone, as the results show a substantial difference between the flowability of the concrete without addition of fibers and other dosages with different types of fibers studied. The compressive strength test at 7 and 21 days also shows resistance as early ages performed fiber, while with increasing days of curing, the resistance becomes a reaction product of cement and pozzolanic water have no effect added fiber. Absorption tests and capillary absorption of water, like the above, consistent with the results shown bibliographic polled, the results being higher in both assays for dosages comprised of PP and sisal fibers.

Abstract: This lecture will outline the past, present and future of research in ceramics. The concept of “ceramic material” has evolved along the time and it hás broadened remarkably for the last decades from traditional clay-based materials to new systems: the term includes now high-performant capacitors, superconductors, highly-efficient oxides, carbides and nitrides of transition metals. The search of new materials has made that their processing and characterization become more technically sophisticated and it has encouraged the development of new techniques and more accurate scientific instruments, altogether providing a wider updated database. The landscape for ceramics research has changed dramatically for the past 15 years, and research in this field is now in a crossroad: in this lecture the emerging areas in ceramic science will be discussed, based upon a workshop held in March 2012 in USA on this regard.

Abstract: To design an energy reduction strategy is necessary to determine the state of the consumer by analyzing companies’ energy indicators. This document presents the energy assessment of the beehive kilns in ​​forty-four (44) companies, and the energy features of the average beehive kiln are described based on 205 analyzed kilns. The diagnosis was made ​​on the following items: information for energy service supplies, information on energy management, energy culture, process facilities, industry basics and environmental management of their waste and emissions. Based on the data gathered from the assessment is shown a summary that involves the energy indicators associated with the management of thermal and electric power on the companies assessed, these were classified into three segments: micro, small, medium and large. High consumption is associated with using low energy efficiency kilns, lack of maintenance practices and the absence of management of energy consumption indicators. Most of the visited companies (71%) have neither maintenance department nor maintenance plans, besides this, the 97.73% of the population surveyed had no knowledge of ISO 50001: Standard Energy Management Systems and the advantages of their application. As for waste recovery, only the use of waste burning (grog) as aggregate in the dough looked up to 5% and rice husk was used as initiator fuel burning beehive kilns.

Abstract: In this work, a waste form olive industry was characterized in terms of its physical–chemical properties, which can be useful for its use in biosorption processes or in pyrolysis units. The characterization results showed that the solid presents a good size distribution to be use as biosorbent or as fuel, although it can be improve with a milled step. The initial moisture content is very high (around 40%), being one of the main characteristics of the solid that makes its direct use as a fuel difficult. However, the low sulfur value (< 0.1%) is very suitable from the environmental point of view, reducing SO₂ emissions. The results of the proximate analysis showed a high content of ashes and the gross calorific value within the range of most biomass waste, was 5100 kcal/kg.

Abstract: The discovery of translucent concrete some years ago, opened a new horizon in Civil Engineering. Many researchers have looked for applications in matter of structural mechanics in order to replace classical concrete by this new and challenging material. However, the scientific and technical communities working in Civil Engineering seem to be still far away from clear ideas and strategies to take profit of one of the main properties of this material: its possibility to transmit light. The reason is complex: on one hand, most of the researchers are mainly interested in the mechanical properties and other researchers, more interested on lighting, maybe find it as a decorative element, but not as a functional one from the point of view of lighting. In this work, two lines concerning its optical characterization (which must be always the first step) and some applications to road tunnels are presented. We will see that more active and multidisciplinary research is still needed before fully understanding and accurately use this material for lighting purposes.

Abstract: This paper presents a review of the environmental possibilities of using carbon nanotubes (CNTs) for extracting metals, taken into account the characteristics of carbon nanotubes to be used as adsorbents and the influence of different factors on the adsorption processes, among them: kind of carbon nanotubes used as adsorbent, particle size, pH of solutions and diameter and length of carbon nanotubes. Also, some images of transmission electron microscopy (TEM), atomic force microscopy (AFM) and molecular modeling (Materials Studio Software) obtained by our research group are presented.