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This paper studies the effect of adding bottom ash from the combustion process of biomass plants to calcium-silicate samples for use as construction material with thermal insulating properties. After a process of physical, chemical and mineralogical characterization of the raw materials, calcium-silicate samples were manufactured by mixing bottom ash (CF) with different sources of lime (calcium oxide-OC and calcium hydroxide-HC) and Portland cement (CM). The amount of bottom ash added ranged from 10% to 90% of the dry weight of the mixtures. The experimental program included a wide range of testing methods of the developed material such as water absorption, mechanical strength, porosity, microstructure, freeze–thaw and thermal conductivity. The optimal values are those containing a 1:1 ratio of SiO2/CaO, with compressive strength ranging from 25.21 MPa (CF/HC) to 61.11 MPa (CF/CM) and thermal conductivity from 0.564 W/m K (CF/OC) to 0.773 W/m K (CF/HC). The initial results obtained make it possible in principle to obtain calcium-silicate samples with low thermal conductivity according EN standard 771-2:2011.

In Mediterranean greenhouses, wood is the most widespread structural element, although it is currently being replaced by galvanized steel. This substitution is not compatible with the change of a productive-constructive model, which seeks to leave a viable environment for the future generations by not exceeding the Earth’s carrying capacity, which is one of the fundamental worries of the humanity. In this sense, the present work examines the possibilities of material application of the bamboo species guadua (Guadua angustifolia), considered as a valid and sustainable alternative for greenhouse design. This initiative consists of analysing the possibilities of guadua as structural material for the “parral” type greenhouse of Almeria. For this characterization, it has been necessary to review the works related to the use of the above-mentioned bamboo species as a building material.

In this study, use of waste produced in biodiesel production plants, as spent earth from biodiesel filtration and the by-product of glycerine, in producing lightweight structural bricks have been investigated. XRD, XRF and TGA–DTA analysis of the waste and clay were performed. Samples containing up to 20 mass% spent earth from biodiesel filtration and up to 15 mass% glycerine have been fired at 1050 °C to produce pores and contribute to auto-thermal combustion due to its high heating power, which involves lower fuel consumption during firing step. Loss on ignition, linear shrinkage, bulk density, apparent porosity, water absorption, water suction, compressive strength, microstructural properties and thermal conductivity values of the fired samples were investigated. The results obtained showed that the use of waste decreased bulk density and increased apparent porosity of sintered samples. Values on mechanical properties decreased, due to the increase in water absorption and water suction, but were higher than those required by the standards. Thermal conductivity of the mixture brick decreased by 20% when spent earth from biodiesel filtration was incorporated, and up to a 40% when glycerine was added. Therefore, biodiesel waste is suitable as secondary raw materials in ceramic brick production.

The main goal of this study is to manufacture ceramic materials by adding the highly hazardous waste “red mud” to a ceramic matrix and neutralizing this waste in the matrix. The optimal proportion of mud to clay was found to be 50%. The samples manufactured were analyzed using XRD to determine the crystalline phases generated, and the microstructure was analyzed using a scanning electron microscope (SEM). Adding this industrial waste to the ceramic structure modifies and improves the physical and mechanical properties due to the great amount of vitreous phase that the waste produces.

This paper studies the application of a variety of waste materials in the production of lightweight bricks: sawdust, spent earth from oil filtration, compost and marble. First, the mineralogical and chemical composition and thermal behaviour of the wastes and clay were determined. Next, ceramic bricks were fabricated with different quantities of waste (0–10 wt.% for sawdust, 0–20 wt.% for marble, and 0–30 wt.% for compost and spent earth from oil filtration). These bricks were fired at 950 and 1050 °C. The effect of adding these wastes on the technological behaviour of the brick was assessed by linear shrinkage, water absorption, bulk density, suction absorption, compressive strength and scanning electron microscopy (SEM). The results have shown that the optimum sintering temperature is 1050 °C. Below this temperature, at 950 °C, increased open porosity was observed, which decreased the compressive strength of the bricks. Based on the results obtained, the optimum amounts of waste were 5 wt.% sawdust, 10 wt.% compost and 15 wt.% spent earth from oil filtration and marble. These percentages produced bricks whose mechanical properties were suitable for use as secondary raw materials in ceramic brick production.

AbstractThis present study has been conducted to assess the viability of mixing increasing amounts of coffee ground as a solid waste material (1–5 wt-%) with raw clay. Samples have been compressed, dried and fired at 950°C for 24 h to laboratory scale. Using coffee grounds as organic residue has been proven to be effective for pore formation in clay body, increasing its insulating properties yet maintaining acceptable mechanical properties. Small amounts of waste (1–2 wt-%) were found to be effective at forming open cell porosity in clay bricks, which results in worse mechanical and thermal insulating properties. However, bricks with higher amounts of coffee grounds (3–5 wt-%) showed lower density levels and, therefore, higher porosity, which is mainly closed cell porosity, which shows higher insulating capacity and suitable mechanical resistance. Optimal results have been found in bricks with 3 wt-% coffee grounds, showing good mechanical, physical and thermal properties.

In this study, various industrial wastes such as urban sewage sludge, bagasse, and sludge from the brewing industry, olive mill wastewater, and coffee ground residue were blended with clay to produce bricks. The clay and waste were characterized by X-ray diffraction, X-ray fluorescence, and thermogravimetric, differential thermal, and chemical elemental analysis. The bricks were manufactured from clay and the optimal proportion of waste. The influence of the waste addition on the linear shrinkage, bulk density, water absorption, and mechanical and thermal properties was investigated. Water absorption increased to above 35% when urban sewage sludge, brewing industry sludge and bagasse were incorporated into the body, but the compressive strength decreased by a maximum of 19% and the thermal insulation increased by at least 8%. The incorporation of coffee grounds and olive mill wastewater of clay was more beneficial, with compressive strength values similar to bricks without waste and a 19% improvement in thermal conductivity. Water absorption and the SEM micrographs indicated that the changes in the results were due to the type of porosity formed by the quantity and the type of waste.

Mullite precursors were prepared using kaolin waste, sericite clay containing kaolinite and industrial kaolin with addition of alumina in a wet medium to synthesize mullite (72 wt% Al2O3 and 28 wt% SiO2). Uniaxial pressed bars of the powdered mullite precursors were fired in the range 1400–1600 °C with soaking times 30–120 min. The resultant materials were studied by XRD and SEM-EDX. Bulk densities, apparent porosities and flexural strengths in four points were determined in the fired bars at 1500, 1550 and 1600 °C. It was concluded that the thermal behaviour of these mullite precursors was influenced by the presence of impurities in the raw materials. These impurities originate a liquid phase forming a glassy phase which produces a progressive and enhanced densification of the mullite materials by reaction sintering at 1500–1600 °C. The technical properties were also influenced by the relative proportion of vitreous phase. The microstructure of characteristic mullite crystals was revealed by SEM. It was emphasized the use of kaolin waste by-products of mining and sericite clays as valuable raw materials for mullite preparation., The present research was supported by Junta de Andalucía through Research Groups TEP 204 and AGR 107.

Galvanic sludge wastes (GSW) are produced by the physico-chemical treatments of wastewater generated by electroplating plants. These materials have a significant potential for the production of clay ceramic bricks. This paper focuses on the viability of the inertization of heavy metals from GSW mixed with clays. The original materials were obtained by mixing three types of raw clay (red, yellow and black) in equal parts with GSW. These mixtures were characterized by XRD, XRF, and chemical elemental analysis CHNS. The dosage of GSW in the clay–GSW bricks was up to 5 wt.%. The bricks were then manufactured using conventional processes. The influence of the amount of GSW was evaluated after firing the clay–GSW composites at 950 °C for 1 h. The engineering properties of the fired samples, such as density, water absorption, open porosity, water suction and compressive strength, with and without the GSW, were determined. The incorporation of GSW into the clay mix clearly decreased the linear shrinkage and bulk density of the bricks in comparison with the fired clay used as a control. These GSW–clay composites also showed lower open porosity. According to the results obtained for the bulk density of the bricks, samples with GSW addition showed slightly lower values of open porosity than clay bodies, indicating that the GSW–clay samples had slightly higher closed porosity values. This was also shown by SEM. The open porosity, SEM and pore size distribution tests indicated that the porosity generated by the addition of GSW was mainly closed and, therefore, GSW bricks had excellent mechanical properties. The environmental risks of the incorporation of GSW, rich in heavy metals (Cr, Zn, Ni and others), to a clay matrix were evaluated by leaching tests of the fired products. The results indicated a successful inertization of the pollutants.

The objective of this study is to investigate the effect of incorporation of ash from biomass incinerator as raw material on the production of ceramic bricks for their application in construction. So, for the fabrication of bricks, compositions were prepared with addition of increasing amounts of waste ash (0%, 10%, 20%, 30%, 40% and 50% in wt.) in the clay body. The mixed samples were sintered using conventional powder processing based on powder compaction at 54.5 MPa and firing them at 950 °C without the addition of additives. Effect on apparent density, water absorption and mechanical properties were investigated. The results showed that water absorption increased and apparent density and compressive strength decreased with higher amounts of ash. Bricks with an ash content up to 20% meet the UNE standards compressive strength. As a result, since interesting performances were observed, the potential use of ashes from biomass incinerator up to 20 wt.% in ceramic formulations of industrial interest was confirmed. In this sense, incorporating ashes into clay body reduces environmental problems and total cost of raw material disposition.

Near infrared (NIR) reflectance and Raman spectrometry were compared for determination of the oil and water content of olive pomace, a by-product in olive oil production. To enable comparison of the spectral techniques the same sample sets were used for calibration (1.74-3.93% oil, 48.3-67.0% water) and for validation (1.77-3.74% oil, 50.0-64.5% water). Several partial least squares (PLS) regression models were optimized by cross-validation with cancellation groups, including different spectral pretreatments for each technique. Best models were achieved with first-derivative spectra for both oil and water content. Prediction results for an independent validation set were similar for both techniques. The values of root mean square error of prediction (RMSEP) were 0.19 and 0.20-0.21 for oil content and 2.0 and 1.8 for water content, using Raman and NIR, respectively. The possibility of improving these results by combining the information of both techniques was also tested. The best models constructed using the appended spectra resulted in slightly better performance for oil content (RMSEP 0.17) but no improvement for water content.