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    A comparative investigation of eco-friendly fly ash-based geopolymer mortar produced by using electrical and heat curing: Mechanical properties, energy consumption and cost
    (Elsevier Sci Ltd, 2024) Urunveren, Husamettin; Beycioglu, Ahmet; Resulogullari, Emriye Cinar; Disken, Nihal Bayramoglu
    This study investigates the eco-friendly fly ash-based geopolymer mortar (GM) production using electrical curing (EC) and heat curing. Within the scope of the study, GM produced using the EC method was compared with GM produced using the heat curing (HC) method in terms of mechanical properties, energy consumption, and cost. The study consists of a preliminary experiment to determine the parameters to be used, mortar experiments using the limited parameters defined in preliminary experiments, and an energy consumption and cost analysis. In the preliminary experiments, different mix designs produced according to different MS modulus and Na 2 O concentrations were studied to decide an applicable range for temperatures of HC and an applicable range for voltages of EC. In the second stage, EC and HC were compared according to temperature changes in GMs, current changes in GMs, and compressive strength (CS). As a final stage, an energy consumption and cost analysis were performed to compare two curing methods according to the updated dollar-based unit prices for electricity per kWh for industrial uses in various countries in February 2024. Results showed that the MS modulus should be at least 1.2 and the Na 2 O concentration should be 10 % on average to obtain a workable mortar. The compressive strength of all mortars with any MS modulus increased up to 100 degrees C and then decreased HC applied samples. Stress values of 20, 25, 30, and 35 volts are applicable and the highest compressive strength values could be obtained with 25 volts, and 6 h of application is sufficient at 25 volts EC. MS module is a key parameter in current and temperature change. In EC application, 30 volts is the threshold value, and when an electrical voltage above 30 volts is applied, the mortar 's internal temperature suddenly reaches the peak value and the desired compressive strength results cannot be achieved. According to the cost analysis, it is seen that the HC electricity cost is 6.78 times more than the EC cost. A comprehensive efficiency calculation is strongly recommended for future studies. It has also been concluded that geopolymers could gain strength at much lower voltage values, so they have the potential to consume less electrical energy in comparison to conventional concrete.
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    Influence of Rock Dust Additives as Fine Aggregate Replacement on Properties of Cement Composites-A Review
    (Mdpi, 2022) Dobiszewska, Magdalena; Bagcal, Orlando; Beycioglu, Ahmet; Goulias, Dimitrios; Koksal, Fuat; Niedostatkiewicz, Maciej; Urunveren, Husamettin
    Concrete production consumes enormous amounts of fossil fuels, raw materials, and is energy intensive. Therefore, scientific research is being conducted worldwide regarding the possibility of using by-products in the production of concrete. The objective is not only to identify substitutes for cement clinker, but also to identify materials that can be used as aggregate in mortar and concrete productions. Among the potential alternative materials that can be used in cement composite production is rock dust of different geological origin. However, some adversarial effects may be encountered when using rock dust regarding the properties and durability of mortars and concrete. Therefore, comprehensive research is needed to evaluate the adequacy of rock dust use in cementitious composite production. This paper presents a comprehensive review of the scientific findings from past studies concerning the use of various geological origins of rock dust in the production of mortars and concrete. The influence of rock dust as a replacement of fine aggregates on cementitious composites was analyzed and evaluated. In this assessment and review, fresh concrete and mortar properties, i.e., workability, segregation, and bleeding, mechanical properties, and the durability of hardened concrete and mortar were considered.
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    Utilization of rock dust as cement replacement in cement composites: An alternative approach to sustainable mortar and concrete productions
    (Elsevier, 2023) Dobiszewska, Magdalena; Bagcal, Orlando; Beycioglu, Ahmet; Goulias, Dimitrios; Koksal, Fuat; Plominski, Blazej; Urunveren, Husamettin
    Production of concrete is consuming significant amounts of raw materials, high level of energy, and is heavily dependent on fossil fuels. This induces significant harmful impact on the environment. Scientific research is being conducted worldwide on the possibility of using different waste by-products in the production of concrete, particularly as a substitute for cement clinker. Rock dust of different geological origin can be considered as potential alternative material that can be used in cement composites production. However, there are some conflicting findings concerning the effect of rock dusts as partial cement replacement on the physical and mechanical properties and durability of cement composites as reported in the literature. Thus, a comprehensive assessment and analysis are needed to evaluate the value of rock dust application as cement replacement in concrete production. This paper presents a comprehensive review of the findings from scientific articles concerning the use of rock dust of different geological origins in mortar and concrete productions. The effect of rock dusts as partial cement substitution on cementitious composites properties were analyzed particularly on the cement hydration, the concrete and mortar mixture properties, mechanical properties and durability. The impact of rock dust is mainly related to the filler effect i.e., due to modification of particle size distribution, heterogenious nucleation, and cement dilution. This effect is more significant when cement is substituted with a rock dust of greater fineness than cement. Partial replacement of cement with up to about 10-15% of rock powder does not deteriorate cement composite properties. However higher substitution leads to reduction of mechanical properties and cement composite durability decline.