Key Engineering Materials Vol. 663

Abstract: The final destination of the wastes generated in the manufacture of pulp paper is one of the growing concerns in this sector, since the European regulations are becoming stricter in regard to their landfill. So it is urgent to seek ways for their valorization through incorporation in other product as, although not usually dangerous, they are generated in substantial quantities.In this work the following residues were used: (i) calcareous sludge generated in the chemical recovery circuit of the production process; (ii) biological sludge generated in the secondary wastewater treatment step and (iii) fly ash from the combustion of biomass in cogeneration operation. The first stage of work was the waste characterization. Then different blends were prepared and submitted to distinct firing cycles to obtain Portland clinker, the main component of the ordinary cement. Using only wastes in adjusted proportions and under tuned firing cycle, it was possible to obtain ecological Portland clinker. Moreover, it was possible to reduce, by about 50 °C, the clinkering temperature in relation to the value used in cement industry, which results in economical and procedural benefits.

Abstract: Since last decades both processes for the production of glass and ceramic materials (known by the generic name of "vitrification") and the processing of the usual ceramic materials ("sintering") are being investigated as a possible way to isolate, inmobilize and even recycling of industrial wastes as a source of "secondary raw materials". Starting from this point of view, the basis for the processing of some of wastes investigated by the author in the last decades are exposed, namely: metallurgy (muds or sludges...), residues from the production of energy (generation power plants, incinerators, nuclear power plants ...) wastes coming from the treatment of minerals and rocks (dumps, mine tailings, muds and machining of natural stone ...), as well as electrical wastes, demolition wastes and finally biomass residues which have been investigated in the recent years. This type of waste and mixtures give rise to synthetic materials with wide uses in construction and public works. Indeed, these are the only industries able to management of high volumes which may be suitable for absorbing a new range of glass, ceramic and glass-ceramic materials from all type of wastes. Experimental results obtained in last decades allow to conclude that both sintering processes as well as vitrification can be considered as an actual and useful, at least partially, for solving the environmental problems generated by all type of wastes.

Abstract: The manufacturing of ceramic tiles in EU generates wastes at different stages of the production process. A significant percentage of these wastes are recycled into the current ceramic products and processes, however nowadays it is not possible to recycle all the waste generated. As a result, an important amount of waste is destined to landfills or used as very low add-valued fillers. LIFECERAM project's main objective is to achieve zero-waste in the manufacture of ceramic tiles through the development of tiles for urban paving with high content of ceramic wastes. The tiles will be manufactured with a highly sustainable body preparation process, based on dry milling and granulation technologies.Although the project is still ongoing, body compositions with 100% of ceramic wastes (fired scraps, green scraps and glaze sludge) have been developed at laboratory scale using the manufacturing process proposed. The recycling of the rest of ceramic wastes (dust from kiln filters and polishing sludge) in the body composition will be investigated at the next phase of the project, in which leaching tests and gaseous emissions during firing will be tested.

Abstract: Virgin raw materials can be partially replaced by glass waste in order to reduce the environmental impact being its recycling a significant problem for municipalities worldwide. In Italy in 2013, approximately 1,600,000 tons of container glass have been collected but it was not possible to recycle all of them in the glass melting process.This work is focused on the valorization of glass waste as raw material in new cement and ceramic products, to convert it from an environmental and economic burden to a profitable, added-value resource in the formulation of new mixes. Several parameters, such as grinding, forming, firing, etc. have been studied.It has been optimized the grinding and the reclaiming step of waste to obtain an alternative raw material for hot and cold consolidation processes. Chemical, physical and mechanical properties of products were carried out. The results show new real possibilities to use high amounts of glass waste as an alternative raw material in products consolidated either by hot or cold techniques, reducing the management problems of the glass waste.

Abstract: This researching work explores the development of new materials and procedures to tackle the configuration of our built environment through the implementation of low-cost biotechnological processes. Particularly, it focuses on two different researching lines: bacterial induced cementation processes and mycelium panel growth from agricultural waste.The first researching line explores the possibilities that MICP (Microbially Induced Calcite Precipitation) shows to improve the engineering properties of granular structures. MICP uses populations of non-harmful bacteria, such as Sporosarcina pasteurii, able to cement sand, silt, or calcarenite, in a growth medium, amended with urea and dissolved calcium source. This researching is mainly grounded on laboratory work. Its main aim is to find out the best conditions to cultivate populations of cementing bacteria and to achieve suitable proportions of urea, bacteria and calcium chloride, in relation to the weight of sand-like granular samples; to come out with effective cementing solutions. These solutions could be used to improve soil stability, to heal concrete cracks, to build roads and paths, to restore monuments, to transform sand into sandstone, etc.The second researching line consists of obtaining 100% organic and biodegradable thermal insulating structures, growing fungi mycelium on agricultural waste. In order to do that, several fungi species were grown on different kinds of agricultural substrates to find out which combination worked better. Therefore, several mycelium growth tests were carried out inside molds that were previously fabricated using CNC machines, such as laser cutters and digital milling machines. Hence, we grew Lentinula edodes (Shiitake) on wood shavings, Pleurotus ostreatus on pasteurized straw, and Ganoderma lucidum (Rehisi) on dried leaves. Several molds with different shapes and sizes were designed and fabricated to grow mycelium inside them, in order to get different outcomes that might be used for different purposes. Hence, we grew insulating panels to be placed in the core of a wall, membrane-like components to cover inside walls, and even structural components that could be assembled to shape 3D complex structures to divide spaces.The whole project, including both researching lines, means a remarkably innovative proposal since the weaving together of biotechnology and design has been hardly explored for all these purposes. Within that logic, its main goal was to achieve sustainable and eco-friendly operational strategies and materials, which take advantage of living forms of intelligence to generate outcomes that meet our needs, without consuming energy and harming the environment.

Abstract: This paper analyzes the influence of an extra calcium source (added as blast furnace slag) on certain properties of fly ash based geopolymers using sodium silicate as activating solution. Geopolymers were manufactured with different fly ash/blast furnace slag (FA/BFS) ratios: 100/0, 80/20, 60/40, 40/60, and 20/80. The properties studied in the geopolymers were their compressive strength and acid attack resistance. The addition of BFS improves geopolymer compressive strength at early stages. Compressive strength increases as the proportion of BFS in the mixture increases. However, maximum compressive strength was found for a determined BFS content value in the geopolymers, so that a clear reduction of this parameter was appreciated when the BFS content increased above this value. The resistance to acid attack improves in the presence of BFS possibly due to the formation of a calcium sulphate precipitate layer that increases the compressive strength and also operates as a protective coating that hinders geopolymer deterioration.

Abstract: From a selection of inorganic industrial waste (screen glass, steelworks ashes, coal power plant ashes, biomass power plant ash and sludge from cutting marble industry) and a waste with organic fraction (diatomaceous earth from oil filtration) it is expected to obtain ceramic materials with properties similar to those of ceramic materials used in construction and porous materials with thermal insulating capability. The ternary phase equilibrium diagram SiO₂-Al₂O₃-CaO has been used as the main tool for the formulation of these materials. The dynamic sintering study was carried out using dilatometry techniques (DIL), thermo gravimetric analysis and differential scanning calorimetry (TG-DSC). Characterization of the manufactured material allows determining a set of basic technological properties such as fired bulk density, water absorption capacity and bending strength, in addition to thermal conductivity and microstructure by SEM-EDX, in order to obtain the necessary data to determine technical feasibility.

Abstract: The main objective of this paper is focused in the use of waste generated by the TiO₂ pigment industry, ilmenite mud (MUD), on the production of ceramic bodies. These ceramic bodies were produced from mixtures of a commercial red stoneware mixture (RSM) with different concentrations of mud (3, 5, 7, 10, 30 and 50 wt%). The samples were sintered to simulate a fast-firing process. The sintering behaviour of the fired samples was evaluated according to ISO rules by linear shrinkage, water absorption and porosity measurements. Both green powder and fired samples were characterised by means of X-ray diffraction (XRD), differential scanning calorimetry (DSC/TG), field emission scanning electron microscopy (FESEM) and bending strength measurements. Moreover, the activity concentrations of radionuclides were measured by high-resolution low-background gamma spectrometry, because this mud is a NORM (Naturally Occurring Radioactive Material) waste. Finally, the TCLP leaching test (Toxicity Characteristic Leaching Procedure, USEPA) was performed to assess the risks of use tiles from an environmental perspective. The results demonstrated that MUD can be successfully valorisated in the manufacture of red stoneware ceramic bodies with similar, or even better technological properties than commercial materials used currently.

Abstract: The properties of ceramic materials are intimately related to a variety of factors, among them shaping procedure and sintering time. These factors condition, the microstructure and properties of the materials developed. Our study has formed materials from clays commonly used in the area of Bailén (Jaén) and wet pomace proceeding from the extraction of olive oil. The materials were shaped through extrusion. In this study, raw materials have been characterized and studied interesting properties of sintered materials, such as compressive strength, water absorption, open porosity or bulk density. The study concluded that the addition of wet pomace from olive oil industry into traditional brick entails a saving of raw materials and reducing the environmental impact generated by their manufacture. The best results are obtained for the samples with waste content of 3 wt %.