Feasibility Study on the Potential Replacement of Primary Raw Materials in Traditional Ceramics by Clayey Overburden Sterile from the Prosilio Region (Western Macedonia, Greece)

The objective of this study was to investigate the valorization potential of clayey overburden sterile materials from lignite-mining activities in the manufacturing of traditional ceramics. This study aims to contribute toward the sustainable management and use of such waste materials in line with the environmental objectives of the 2030 agenda. To assess this issue, clayey steriles were incorporated in a white clay-body at 20, 50, and 80 wt%, whereas reference samples were also formed from the individual raw materials. Laboratory processing of the ceramics was performed by dry pressing loose powder into rectangular samples and firing at 1000 °C for 4 h. Characterization of the raw materials included chemical, mineralogical, and thermal analysis. The fired bodies were tested for their total linear shrinkage, apparent porosity, water absorption, bulk density, and bending strength according to the relevant standards. The microstructural evolution of the final bodies was analyzed by scanning electron microscopy, which observed differences related to the addition of the steriles. The results showed that the tested clayey steriles can be utilized up to 50 wt% as a secondary raw material in the production of ceramic materials (e.g., bricks) with comparable properties to the reference clay-bodies. Furthermore, the color of the final samples changed from white-creamy to reddish as the content of clayey sterile materials increased in the raw mix

Production of Lightweight Aggregates from Different Types of Boron Wastes

Four boron wastes (BW), named as Sieve (SBW), Dewatering (DBW), Thickener (TBW) and Mixture (MBW) waste, from Kirka plant (Turkey) were investigated for the formation of Artificial Lightweight Aggregates (LWA). The characterization involved chemical, mineralogical and thermal analyses. The bloating behavior was examined by heating microscopy. SBW and DBW expanded in two stages, at 300°C approximately and subsequently at 550°C with concurrent formation of liquid phase. However, at 650-700°C there is excessive liquid phase formed resulting in large, non uniform porosity of irregular shape. On the contrary, in the case of TBW and MBW no noticeable expansion or glassy surface was formed. An optimization route, involved the formation of a mixture with 20wt% clay, 40wt% SBW, 40wt% DBW and one with 20wt% clay, 35wt% SBW, 35wt% DBW, 10wt% quartz sand. The raw aggregates were fired in a rotating crucible at 650°C, 700°C, 710°C and 760°C for 2-5 min. It was observed that the clay addition leads to better plasticity and cohesion between the particles whereas the quartz addition shifts the softening point 50°C higher. Water absorption was 56.8-60.5%, apparent specific gravity 2.3-2.4g/cm and bulk density 0.9-1.1g/cm3. The analysis of microstructure with electron microscopy revealed a glassy phase matrix and an extended formation of both open and closed pores. The results indicate that SBW and DBW boron wastes can be utilized in LWA production

A Contribution towards a More Sustainable Cement: Synergy of Mill Scales, Greek Wet Fly Ash, Conventional Raw Materials and Clinkering Temperature

Portland cement is the most common type of cement and one of the most important ingredients in concrete. Concrete, on the other hand, is the most used building material worldwide just behind the water with an increasing usage trend in infrastructure for the upcoming years. During the production process of cement, massive CO2 emissions are released into the environment, while large amounts of raw materials and energy are consumed. In the present study, Portland type cement was prepared in laboratory-scale by Greek Wet Fly Ash and Mill Scales, as well as conventional raw materials such as limestone, shale and lava. The experiments were conducted at 1450 °C and 1340 °C. The fired compositions were characterized by XRD, Q–XRD, optical microscopy, SEM/EDS and the concrete specimens were tested for their compressive strength. The results indicated that formation of cement clinker at lower temperatures (1340 °C) is feasible with the combined use of natural raw materials and industrial byproducts following the standard production route of cement industries. Finally, the so-obtained cement presented compressive strength values comparable to the conventional ones fired at 1450 °C

Carbon Footprint of the University of Patras in Greece: Evaluating Environmental Culture and Campus’ Energy Management towards 2030

Climate change has already had observable effects due to greenhouse gases (GHG) produced by human activities. Over the years, this becomes more evident as the concentration of GHG released in the atmosphere is concerningly increased as does the earth’s average temperature too. Hence, all countries and many independent organizations are taking actions to reduce the Global Warming phenomenon by setting targets for carbon dioxide emissions. The energy sector is proved to play the most important role in emissions reduction. Greece’s target for this sector is very ambitious in total transformation of energy mixture in the forthcoming years. Universities are also contributing to GHG emissions through their operations and members’ activities. Energy management at the University of Patras in Greece has already started since 2019 by installing energy meters going from manual calculations to an online system. The reliable records and accurate calculations proved as a very important action and a starting point for performing detailed analysis. In this study, there was an effort to calculate the CO2 emissions of the University of Patras using the Carbon Campus Calculator. The results showed that the students commuting is the main source of GHG emissions at the University of Patras and the purchased electricity comes next. These two factors together comprise 60.2% of the total emissions and priority should be given to reducing their footprint. Specific targets were set up for 2030 in compliance with the National Plan for Energy and Climate of Greece. Moreover, an Action Plan managing carbon and energy more efficiently and creating a strong environmental culture among the community is proposed. In the future, the university’s management team should act proactively in every change at Patras University. An assessment on the environmental impact should take place before any decision making. If necessary, extra actions should be defined in order not to deviate from the targets and new standards set

A Contribution towards a More Sustainable Cement: Synergy of Mill Scales, Greek Wet Fly Ash, Conventional Raw Materials and Clinkering Temperature

Portland cement is the most common type of cement and one of the most important ingredients in concrete. Concrete, on the other hand, is the most used building material worldwide just behind the water with an increasing usage trend in infrastructure for the upcoming years. During the production process of cement, massive CO2 emissions are released into the environment, while large amounts of raw materials and energy are consumed. In the present study, Portland type cement was prepared in laboratory-scale by Greek Wet Fly Ash and Mill Scales, as well as conventional raw materials such as limestone, shale and lava. The experiments were conducted at 1450 °C and 1340 °C. The fired compositions were characterized by XRD, Q–XRD, optical microscopy, SEM/EDS and the concrete specimens were tested for their compressive strength. The results indicated that formation of cement clinker at lower temperatures (1340 °C) is feasible with the combined use of natural raw materials and industrial byproducts following the standard production route of cement industries. Finally, the so-obtained cement presented compressive strength values comparable to the conventional ones fired at 1450 °C

Production of Lightweight Aggregates from Different Types of Boron Wastes

Four boron wastes (BW), named as Sieve (SBW), Dewatering (DBW), Thickener (TBW) and Mixture (MBW) waste, from Kirka plant (Turkey) were investigated for the formation of Artificial Lightweight Aggregates (LWA). The characterization involved chemical, mineralogical and thermal analyses. The bloating behavior was examined by heating microscopy. SBW and DBW expanded in two stages, at 300°C approximately and subsequently at 550°C with concurrent formation of liquid phase. However, at 650-700°C there is excessive liquid phase formed resulting in large, non uniform porosity of irregular shape. On the contrary, in the case of TBW and MBW no noticeable expansion or glassy surface was formed. An optimization route, involved the formation of a mixture with 20wt% clay, 40wt% SBW, 40wt% DBW and one with 20wt% clay, 35wt% SBW, 35wt% DBW, 10wt% quartz sand. The raw aggregates were fired in a rotating crucible at 650°C, 700°C, 710°C and 760°C for 2-5 min. It was observed that the clay addition leads to better plasticity and cohesion between the particles whereas the quartz addition shifts the softening point 50°C higher. Water absorption was 56.8-60.5%, apparent specific gravity 2.3-2.4g/cm and bulk density 0.9-1.1g/cm3. The analysis of microstructure with electron microscopy revealed a glassy phase matrix and an extended formation of both open and closed pores. The results indicate that SBW and DBW boron wastes can be utilized in LWA production

Valorization of red mud as raw material in the production of belite cement clinkers

status: publishe

Utilization of Industrial Ferronickel Slags as Recycled Concrete Aggregates

The scope of this study focuses on the use of two different types of industrial byproducts such as slags (FeNi and Electric Arc Furnace slag) combined with natural sand as concrete aggregates as well as the evaluation of their suitability on the final physicomechanical behavior of the produced concrete specimens. For this reason, twelve concrete specimens were prepared using variable concentrations of these slags which were compared to concrete specimens made by natural rocks as aggregates (limestones). The mineralogical, petrographic, chemical and morphological characteristics of these raw materials were related to the physicomechanical characteristics of the produced concrete specimens. Those concrete specimens containing aggregates of higher amount of Electric Arc Furnace slags seems to present better mechanical strength both in 7 and in 28 days of curing regarding the other mixtures and regarding the specimens made by natural rocks as aggregates (limestones). This is due to the mineralogical, textural and morphological characteristics of the tested slags, which lead to a better bonding between them and the cement paste making them at the same time a promising alternative in the production of green concrete for construction applications. The compact texture of slags is responsible for the stronger bonding with the aggregates in relation to the unevenly distributed porosity of the natural aggregates. Wüstite presents negative effect on the final mechanical strength of concrete specimens which is documented both by the microscope images and by the three-dimensional study of the produced concretes

Formation, Characterization and SEM Microanalysis of Yeelimite

Yeelimite is one of the main components of SulfoBelite (SB) and Calcium SulfoAluminate cements which are promising low carbon alternatives to Portland ones. In this study, stoichiometric yeelimite, obtained at different temperatures, was characterized by XRD, Q-XRD and SEM-EDS. Additionally, mortars of the synthetic yeelimite, with and without standard sand, were studied in terms of the development of strength over time. The main result is that high yeelimite content samples were prepared by mixing stoichiometric quantities of analytical-grade raw materials at 1330 °C for 3 h soaking time, followed by rapid cooling. Moreover, an increase in the formed yeelimite results in increased strength values that meet the requirements to be classified at CEM 32.5

Formation, Characterization and SEM Microanalysis of Yeelimite

Yeelimite is one of the main components of SulfoBelite (SB) and Calcium SulfoAluminate cements which are promising low carbon alternatives to Portland ones. In this study, stoichiometric yeelimite, obtained at different temperatures, was characterized by XRD, Q-XRD and SEM-EDS. Additionally, mortars of the synthetic yeelimite, with and without standard sand, were studied in terms of the development of strength over time. The main result is that high yeelimite content samples were prepared by mixing stoichiometric quantities of analytical-grade raw materials at 1330 °C for 3 h soaking time, followed by rapid cooling. Moreover, an increase in the formed yeelimite results in increased strength values that meet the requirements to be classified at CEM 32.5