The effect of the addition of construction & demolition waste on the properties of clay-based ceramics

Waste glass and reclaimed brick are types of construction and demolition waste (C&DW) that could potentially be used as secondary raw materials in the production of ceramics. Ceramics based on clay, waste demolished brick (5-15 wt.%) and waste glass (5-20 wt.%) were produced by pressing (P = 68 MPa) and subsequently sintered at 900, 950, 1000, and 1050 ° C for one hour. The physical and mechanical properties of the ceramics obtained were evaluated. The addition of demolished brick decreased the density and mechanical properties of the clay specimens and increased the water absorption. The incorporation of waste glass improved the sintering behavior and its mechanical properties. The addition of 20 wt.% waste glass and 10 wt.% waste demolished brick into the clay matrix improved the flexural strength by up to 20.6 % and decreased the water absorption by up to 22 %. The approach presented promotes an opportunity to recycle construction and demolition waste into alternative resource materials, and represents a positive contribution to the environment

Technical and radiological characterisation of fly ash and bottom ash from thermal power plant

Huge quantities of fly ash and bottom ash are generated from thermal power plants and it presents great concern for country, mainly due to the environmental effects. In this study, fly ashes and bottom ash were characterized from technical and radiological aspects. Health effect due to the activity of radionuclides 226Ra, 232Th and 40K was estimated via radium equivalent activity (Raeq), external hazards index (Hex), the external absorbed dose rate (D) and annual effective dose rate (EDR). The specific surface area (40.25 m2 g−1), particle density (1.88 g cm−3) and LOI (23.49%) were typical for bottom ash. Siliceous fly ash contained 32% reactive silica. The annual effective dose rate for all ashes is ≤ 0.2 mSv y−1. Both, fly ash and bottom ash present potential secondary raw materials to be used for building purposes as result of their technological and radiological assessment

Manual for use of Al-containing residues in low-carbon mineral binders

Our society can no longer be imagined without its modern infrastructure, which is inevitably based on the use of various mineral and metallic materials and requires a high energy consumption. Parallel to the production of materials, as well as the production of electricity, huge amounts of various industrial and mining residues (waste/by-product) are generated and many of them are sent to landfill. The European Union (EU) aims to increase resource efficiency and the supply of ”secondary raw materials“ through recycling [1], inventory of waste from extractive industries [2], and waste prevention, waste re-use and material recycling [3]. Much of the industrial and mining waste is enriched with aluminium (Al) and therefore has a potential to replace natural sources of Al in mineral binders with a high Al demand. However, the use of industrial residue in mineral binders requires an extensive knowledge of its chemical composition, including potential hazardous components (e.g. mercury), mineral composition, organic content, radioactivity and physical properties (moisture content, density, etc.). This manual addresses the legislative aspects, governing the use of secondary raw materials in construction products, description of the most common Al-containing industrial and mining residue (bauxite deposits, red mud, ferrous slag, ash and some other by products from industry), potentiality for their reutilisation and its economic aspects, potential requirements/barriers for the use of secondary raw materials in the cement industry and a description of belite-sulfoaluminate cements, which are a promising solution for implementing the circular economy through the use of large amounts of landfilled Al-rich industrial residue and mining waste cement clinker raw mixture. This manual was prepared by partners of the RIS-ALiCE project. It provides a popular content, which targets relevant stakeholders as well as the wider society. Moreover, it offers education material for undergraduate, master and PhD students.Other links: [http://www.zag.si/dl/manual-alice.pdf

Production and Characterization of Porous Ceramics From Coal Fly Ash and Clay

The disposal of coal fly ash obtained in thermal power plants presents the general problem all over the world. Significant research on the utilization of fly ash has been carried out in the area of construction materials. The aim of this study was to develop porous ceramics based on coal fly ash and clay (60wt.%clay and 40wt.% fly ash). Three types of pore creators: two types of wood cutting (Quercus and Facus sylvatica) and C-powder were used for creating of the porous ceramics. The mixtures based on fly ash and clay and different content of pore creators (2, 5, 10 and 20wt.%) were consolidated (P=45 MPa, T = 900, 1000, 1050 and 1100oC/1h) to obtain porous ceramic (PC). The results indicate that the properties of the porous ceramics depend on the type and content of the pore creators. Furthermore, the sintering temperature was found to be main factor affecting the properties of the sintered products. The maximal bending strength (26 MPa) was achieved by using 2wt% P3 (C-powder) and the porous ceramics has the density and porosity of 1.90g/cm3 and 22%, respectively. By using the highest content (20wt.% ) of each pore creator (P1, P2 and P3) the lowest bending strength cca 5 MPa was achieved and the variation of the density and porosity was in the range from 1.22 to 1.32 g/cm3 and 44 to 48%, respectively. Water absorption, durability and the microstructure of the obtained porous ceramics are also reported in this paper

Adsorption properties and porous structure of sulfuric acid treated bentonites determined - SHORT COMMUNICATION

In a previous paper adsorption isotherms of benzene vapor on natural bentonite from Ginovci, Macedonia, and forms acid activated with 10 % and 15 % solutions of hydrochloric were interpreted by means of the DubininRadushkevichStoeckli and DubininAstakhov equations; the investigation has been continued with bentonites acid activated with 10 % and 15 % solutions of sulfuric acid where X-ray analysis indicates smaller structural changes. Using the above equations, the heterogeneity of the micropores and the energetic heterogeneity of the bentonites were determined from the differential distribution of the micropore volume with respect to the structural parameter of the equations characterizing the microporous structure and to the molar free energy of adsorption. Activated bentonites obtain bigger pores but also a certain quantity of new small pores appear during acid activation with the higher concentration of acid. The micropore volumes, determined from the adsorption of benzene vapor, of bentonites activated with 10 % and 15 % solution of hydrochloric acid (144.60 cm3 kg-1 and 110.06 cm3 kg-1, respectively), decrease in comparison with that of natural bentonite (162.55 cm3 kgv).1 In contrast, the values of the micropore volume for bentonities treated with 10 % and 15 % solutions of sulfuric acids increase (169.19 cm3 kg-1 and 227.74 cm3 kg-1). That is due to the difference in the structural changes occurring during activation with hydrochloric and sulfuric acids. The values of the free energy of adsorption of benzene vapor for natural bentonite are higher than those of the acid acitivated bentonities, what is in accordance with the structural and porosity changes

Influence of the Main Process Parameters on the Physical and Mechanical Properties of the Bottom Ash Ceramics

Bottom ash has been presented as a major problem of disposal throughout the world, since it is produced from the process of coal combustion in thermal power plants. However, its physical and chemical properties make the bottom ash an adequate potential construction material in variety of applications.The aim of the study was to investigate the possibility of utilization of bottom ash for production of ceramics compacts and to analyse the influence of the main process parameters and their interaction on the physical and mechanical properties of the final product. Consolidation of the powders was conducted on two bottom ash samples with particle size (S) -0.250+0.125 mm and -0.500+0.250 mm, pressing pressure (P) of 100 and 150 MPa and sintering temperature (T) of 1100 and 1150 oC. The density (r) and bending strength (s) of the dense bottom ash compacts were the response function. The optimization was performed through implementation of main effect plots, Pareto charts and 3D surface method using “Statgraphics Centurion” software package. The obtained model equations of the density and bending strength dependence from the main process parameters are solid basic data for modeling the process of ceramic production

PRODUCTION OF GLASS-CERAMICS FROM WASTE MATERIALS AND OPTIMIZATION OF THE MAIN PROCESS PARAMETERS

In this study the 3D surface model was successfully applied in investigating the influence of theprocess parameters on the physical and mechanical properties of the glass-ceramics. Glassceramicswas produced from coal fly ash and waste glass through the sintering method. The rawmaterial was taken from “REK Bitola”, a thermal power plant in the Republic of Macedonia.Glass-ceramics was obtained through the process of consolidation. Compacts with different ratio offly ash and waste glass were pressed at 45 MPa, sintered in the temperature interval from 1000 to1100oC, and isothermal time at the final temperature from 1h to 5h. The process of optimizationwas conducted on the process parameters such as quantity of glass, sintering temperature andisothermal time. According to the results of the process of optimization presented by the softwarepackage, a final model equations of the density and bending strength dependence were obtained

Optimization of the Process of Production of Ceramics From Waste Coal Ash Case Study: The Influence of the Mechanical Activation

Abstract: Fly ash, a waste by-product obtained in a thermal power plant has been a generated problem of the disposal all over the world. Morphological characteristics, physicochemical properties and pozzolanic activity make this waste potential material for production of ceramics. In this study high density ceramics compacts were produced by using fly ash from the power plant REK Bitola, Republic of Macedonia. In order to increase geometrical factor of activity, the mechanical activation of the fly ash was applied. The process of optimization of the main process parameters is conducted, such as time of mechanical activation, sintering temperature and heating rate and their interactions on the properties of obtained dense ceramic porosity and bending strength as a response function. The optimization was performed through application of 3D surface method and the obtained results are presented in the graphical and analytical form using “Statgraphics Centurion” software package