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    Cement mortar composites including 1-tetradecanol@PMMA Pickering emulsion particles for thermal energy management of buildings
    (Elsevier Science Sa, 2023) Alkan, Cemil; Alakara, Erdinc Halis; Aksoy, Sennur Alay; Demir, Ilhami
    In this study, a poly(methyl methacrylate) (PMMA) shell 1-tetradecanol core microencapsulated phase change material (MPCM) was produced using the Pickering emulsion technique. Characterization tests of the produced MPCMs were performed using Fourier transform infrared (FT-IR) spectroscopy, particle size distribution (PSD) analysis, differential scanning calorimetry (DSC), scanning electron microscopy (SEM) and thermogravimetric analysis (TGA) techniques. The latent heat, melting temperature and encapsulation rate of MPCM were determined and they were found as 108.4 J/g, 33 degrees C, and 46.7 % for heating period, respectively. The effect of 1-tetradecanol@PMMA MPCM on the physical, mechanical, and thermal performance properties of cementitious mortars was also investigated in the study. For this reasons 1-tetradecanol@PMMA MPCMs are included in mortar mixes at 5 %, 7.5 %, and 10 % by weight of cement. As the MPCM ratio increased, the water absorption rate and porosity increased, while the workability, unit weight of the mortar, ultrasonic pulse velocity, flexural strength and compressive strength parameters decreased. The compressive strength of the mortar containing 10 % MPCM on the 28th day was measured as 34.74 MPa. The highest thermal storage capacity was found in mortars containing 10 % MPCM. When the thermal performance of the reference and 10 % MPCM-containing mortars were compared, the indoor temperature differences at the end of the heating and cooling periods were measured as 4.7 degrees C and 3.9 degrees C, respectively. The results showed that MPCM produced by the Pickering emulsion technique has the potential to increase thermal comfort in buildings, reduce fuel consumption used for heating purposes and, accordingly, reduce carbon emissions.
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    Effect of magnetic water on properties of slag-based geopolymer composites incorporating ceramic tile waste from construction and demolition waste
    (Springernature, 2023) Sevim, Ozer; Alakara, Erdinc Halis; Demir, Ilhami; Bayer, I. Raci
    This study investigates the effect of magnetic water (MW) on the properties of slag-based geopolymer composites (SGCs) incorporating ceramic tile waste (CTW) from construction and demolition waste (CDW). The presented study consists of two stages. In the first stage, reference mortars without additives were produced, and optimum parameters for molarity, curing temperature and curing time were determined. Tap water (TW) was used as mixing water, and blast furnace slag (BFS) was used as a precursor in SGCs in this stage. SGCs were produced using different alkali activator concentrations (12, 14 and 16 M) and were cured for either 24 or 48 h in an oven at ranging from 60 to 110 degrees C. Ultrasonic pulse velocity (U-pv), flexural strength (f(fs)), and compressive strength (f(cs)) tests were performed on the produced SGCs. The results of these tests indicated that optimum paramaters for molarity, curing temperature and curing time parameters were determined to be 16 M, 100 celcius and 24 h, respectively. Then, TW and MW were used as mixing water, and BFS and CTW were used as precursors in the second stage. At this stage, SGCs were produced using 16 M and cured in an oven at 100 celcius for 24 h. In the mixtures, CTW was used by substituting 10, 20, 30 and 40% by weight of BFS. In the second stage, workability, U-pv, f(fs), and f(cs) tests as well as microstructure analyses, were performed on the produced SGCs. Microstructure analyses were performed with scanning electron microscopy (SEM). According to the results, U-pv, f(fs), and f(cs) increased compared to the reference SGCs when 10% of CTW was used. Additionally, when MW was used as mixing water, there were increases in workability, U-pv, f(fs), and f(cs) results compared to those produced with TW. From SEM analyses, it has been observed that MW accelerates the polymerization process of SGCs containing CTW and reduces the pore size of SGCs. As a result, it has been determined that MW can improve the fresh and hardened state properties and microstructures of SGCs containing CTW.
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    Effect of magnetized water on alkali-activated slag mortars incorporating raw and calcined marble powder
    (Elsevier Sci Ltd, 2024) Demir, Ilhami; Alakara, Erdinc Halis; Sevim, Ozer; Kartal, Saruhan
    This study investigates the impact of magnetized water (MW) on the fresh and hardened properties of alkaliactivated slag (AAS) mortars incorporating raw marble powder (RMP) and calcined marble powder (CMP). In the initial stage of the study, control specimens were manufactured to ascertain the optimal parameters for molarity, curing temperature, and curing time. The optimal parameters were determined based on the highest strength results: a molarity of 10, curing time of 24 hours, and curing temperature of 110 degree celsius. In the second stage of the study, while maintaining these optimal parameters, RMP and CMP were substituted in place of blast furnace slag (BFS) at rates of 10%, 20%, 30%, and 40%. In this study stage, tap water (TW) and MW were employed as the mixing water. A mini -slump test was conducted to assess the fresh state properties of the prepared AAS mortars. Subsequently, ultrasonic pulse velocity ( U p v ), flexural strength ( f f ), and compressive strength ( f c ) tests were carried out to evaluate the hardened state properties of the specimens. Finally, scanning electron microscopy (SEM) analysis was performed to examine microstructural properties. According to the results, the f f and f c values of the mortars produced with CMP substitution using TW showed an increase of up to 20.6% compared to the mortars based on RMP and produced withTW. Additionally, utilizing MW as the mixing water enhanced the workability of AAS mortars. Consequently, incorporating CMP and MW in AAS mortars further improved fresh and hardened state properties compared to RMP and TW.
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    Experimental Evaluation of New Geopolymer Composite with Inclusion of Slag and Construction Waste Firebrick at Elevated Temperatures
    (Mdpi, 2023) Sevim, Ozer; Demir, Ilhami; Alakara, Erdinc Halis; Bayer, Ismail Raci
    This study investigates the effect of elevated temperatures on slag-based geopolymer composites (SGC) with the inclusion of firebrick powder (FBP). There is a limited understanding of the properties of SGC with the inclusion of FBP when exposed to elevated temperatures and the effects of cooling processes in air and water. In this regard, in the preliminary trials performed, optimum molarity, curing temperature, and curing time conditions were determined as 16 molarity, 100 degrees C, and 24 h, respectively, for SGCs. Then, FBP from construction and demolition waste (CDW) was substituted in different replacement ratios (10%, 20%, 30%, and 40% by slag weight) into the SGC, with optimum molarity, curing temperature, and curing time. The produced SGC samples were exposed to elevated temperature effects at 300, 600, and 800 degrees C and then subjected to air- and water-cooling regimes. The ultrasonic pulse velocity, flexural strength, compressive strength, and mass loss of the SGCs with the inclusion of FBP were determined. In addition, scanning electron microscopy (SEM) analyses were carried out for control (without FBP) and 20% FBP-based SGC cooled in air and water after elevated temperatures of 300 degrees C and 600 degrees C. The results show that the compressive and flexural strength of the SGC samples are higher than the control samples when the FBP replacement ratio is used of up to 30% for the samples after the elevated temperatures of 300 degrees C and 600 degrees C. The lowest compressive and flexural strength results were obtained for the control samples after a temperature of 800 degrees C. As a result, the elevated temperature resistance can be significantly improved if FBP is used in SGC by up to 30%.
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    Experimental study on firebrick powder-based cementitious composites under the effect of elevated temperature
    (Elsevier, 2022) Alakara, Erdinc Halis; Sevim, Ozer; Demir, Ilhami; Simsek, Osman
    This study investigates the effect of elevated temperature on cementitious composites with 5, 10, 15, 20, and 25% firebrick powder (FBP). In this regard, cementitious composite mortars with di-mensions of 40 x 40 x 160 mm, which were water-cured at 20 +/- 2 degrees C for 56 days, were pro-duced. Produced samples were exposed to 300, 600, 750, and 900 degrees C, then air-and water-cooling processes were applied. Cooling processes were continued until the samples reached the labora-tory temperature. Unit weight, ultrasonic pulse velocity, compressive strength, and mass loss of the FBP-based cementitious composite samples were measured after both air-and water-cooling regimes. Finally, microstructural analysis was performed for reference samples and samples with 20% FBP. As a result, the compressive strengths of the samples exposed to 600, 750, and 900 degrees C showed that up to 15% of FBP-based cementitious composite samples had better results com-pared to the reference samples. The compressive strengths of the water-cooled samples were lower than those of the air-cooled samples. The mass loss results of FBP-based samples decreased with the increase in temperature. The mass loss of the air-cooled samples was higher than that of the water-cooled samples.