Person: MARDANİ, ALİ
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MARDANİ
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ALİ
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Publication Recycling of sewage sludge incineration ashes as construction material(Gazi Üniversitesi Mühendislik Mimarlık Fakültesi, 2020-01-01) Yiğit, Berna; Salihoğlu, Güray; Mardani-Aghabaglou, Ali; Salihoğlu, Nezih Kamil; Özen, Süleyman; Yiğit, Berna; SALİHOĞLU, GÜRAY; MARDANİ, ALİ; SALİHOĞLU, NEZİH KAMİL; Bursa Uludağ Üniversitesi/Mühendislik Fakültesi/Çevre Mühendisliği Bölümü; Bursa Uludağ Üniversitesi/Mühendislik Fakültesi/İnşaat Mühendisliği Bölümü; 0000-0003-0714-048X; 0000-0003-0326-5015; AAG-9399-2021; AAG-9413-2021; AAJ-6415-2021; C-7860-2015; EHO-7411-2022Sewage sludges that are originating from the municipal wastewater treatment plants of Bursa city have been incinerated with a fluidized bed reactor of 400 tons/day capacity since 2017. Each month, on an average, 615 tons of ash is generated as a waste of the incineration process, which needs disposal. The purpose of this study was to investigate if the sludge incinerator ash can be recycled as a construction material. Stabilization/solidification (S/S) and geopolymerization technologies were applied to the sludge ash with this aim. Portland cement, fly ash from a coal-fired power plant, and marble sludge were used as binders. S/S samples were activated with water, while geopolymer samples were activated with 8MNaOH and NaSilNaOH solutions. The prepared paste samples were air-cured for 28 days and analyzed for compressive strength and heavy metals leaching. S/S samples containing sludge ash yielded a compressive strength level of 21.8 MPa, while geopolymer samples resulted in a compressive strength level of 50.0 MPa. Higher compressive strength levels of several samples containing waste sludge ash than that of the control samples without waste were noticed. Leaching tests showed that heavy metals leaching from the samples prepared with sludge ash were much lower than the legal limit values for toxicity. Both leaching tests and compressive strength tests showed that sludge ash has the potential to be considered as a construction material.Publication Effect of polycarboxylate-based water-reducing admixture chains length on portland cement-admixture compatibility(Taylor & Francis Ltd, 2023-08-31) Felekoğlu, Burak; Ramyar, Kambiz; Kobya, Veysel; Karakuzu, Kemal; Mardani, Ali; MARDANİ, ALİ; Bursa Uludağ Üniversitesi/Mühendislik Fakültesi/İnşaat Mühendisliği Bölümü.; 0000-0002-1023-3962; 0000-0003-0326-5015; 0000-0003-2200-2691; C-7860-2015This study investigated, the effect of polycarboxylate-based water-reducing admixture (PCE) molecule chain length modification on the cementadmixture compatibility. Seven PCEs with varying chain lengths were synthesized for this aim. Paste and mortar mixtures were prepared by combining a high C3A (9.1%) CEM I-42.5 R-type cement with PCEs. The Marsh-funnel flow time, mini-flow, dynamic yield shear stress, final viscosity and setting times of the paste mixtures were analyzed. The PCE requirement for target flow, the time-dependent flow performance, and compressive strength of mortar mixtures were studied. In this way, effects of the change in only the main chain length, only the side chain length, and both main and side chain lengths of PCE molecule on the Portland cement-admixture compatibility were comparatively researched. Consequently, the PCE with medium main and side chain lengths exhibited the best performance and was the most compatible with high C3A cement in terms of the examined properties.Publication Improving the mechanical and durability performance of recycled concrete aggregate-bearing mortar mixtures by using binary and ternary cementitious systems(Elsevier Sci Ltd, 2019-02-05) Yüksel, Cihat; Beglarigale, Ahsanollah; Ramyar, Kambiz; Mardani-Aghabaglou, Ali; MARDANİ, ALİ; Bursa Uludağ Üniversitesi/Mühendislik Fakültesi/İnşaat Mühendisliği Bölümü.; 0000-0003-0326-5015; C-7860-2015Environmental concerns arising from the generation of huge amount of construction and demolition waste requires recycling this material, which would otherwise be sent to landfill. The mechanical and durability performance of mortar mixtures containing recycled concrete (RC) aggregate was investigated in this study. Although it is known that the adhered mortar creates a porous and a weak additional interfacial transition zone in recycled aggregate-bearing mixture, the dependence of the behavior on the type of new matrix should be searched in detail. For this purpose, compressive strength, ultrasound pulse velocity, water absorption, chloride ion penetration, freeze-thaw and sulfate resistance as well as drying shrinkage tests were conducted on mortar mixtures containing either natural aggregate (sand) or recycled concrete aggregate. Scanning electron micrographs and optical microscope images were obtained on specimens exposed to sulfate attack. The mineral admixtures used in the study included silica fume (SF), metakaolin (MK) and a Class C fly ash (FA). In addition to the control mixture including no mineral admixture (PC), silica fume- and metakaolin-incorporating binary systems (PC-SF and PC-MK) were prepared. Besides, two ternary systems, i.e., PC-SF-FA and PC-MK-FA were also designed. The results indicated a gradual strength gain beyond 28 days and reduction in initial shrinkage values in RC-bearing mixtures, compared to those of the sand-bearing mixtures. Besides, the porous character of RC helped reducing the internal pressure and resultant damage related with expanding water and swelling ettringite crystals in freeze-thaw and sulfate attack tests, respectively. The exact effect of recycled aggregate on mortar properties was found to be greatly dependent on the type of the cementitious system of the new mix.Publication Effect of chain characteristics of polycarboxylate-based water-reducing admixtures on behavior of cementitious systems: A review(Asce-amer Soc Civil Engineers, 2023-08-01) Felekoğlu, Burak; Ramyar, Kambiz; Kobya, Veysel; Karakuzu, Kemal; Mardani, Ali; MARDANİ, ALİ; Bursa Uludağ Üniversitesi/Mühendislik Fakültesi/İnşaat Mühendisliği Bölümü.; Bursa Uludağ Üniversitesi/Mühendislik Fakültesi/İnşaat Mühendisliği Bölümü.; 0000-0002-1023-3962; 0000-0003-0326-5015; 0000-0002-7426-1698; C-7860-2015Polycarboxylate ether-based water-reducing admixtures (PCEs) have a significant impact on the workability of cementitious systems. The modifications of the chemical structures of the main and side chains can lead to the improvement of electrostatic repulsion and steric hindrance effect of PCEs, resulting in the superior performance of cementitious systems. In this study, the impact of main- and side-chain properties of PCEs on various characteristics, especially the rheology of cementitious systems, was examined in detail via prior studies in the literature. In addition, pH, adsorption conformation, and intercalation state, which affect the aforementioned properties of PCEs, also were studied. It was concluded that the geometric equilibrium between the main and side chains has a vital place in designing optimum molecular structures.Publication How does rheological behaviour affect the interlayer-bonding strength of 3dpc mixtures?(Taylor & Francis Ltd, 2023-10-06) Şahin, Hatice Gizem; Mardani, Ali; MARDANİ, ALİ; Bursa Uludağ Üniversitesi/Mühendislik Fakültesi/İnşaat Mühendisliği Bölümü.; 0000-0002-8915-879X; 0000-0003-0326-5015; C-7860-2015; IAQ-9713-2023; AAE-2420-2022The biggest obstacle to become widespread 3D Printing Concrete (3DPC) is the insufficient interlayer-bonding strength (IBS). The parameters affecting the IBS are classified as physical effects such as cleanliness and roughness, effects caused by the material properties it contains, and printer-induced effects for instance interlayer interval time, nozzle shape and printing speed. However, it was stated that the rheological properties of 3DPC mixtures should also be examined in order to strengthen the IBS. In this article, the relationship between IBS and rheological properties of 3DPC mixtures is discussed. It was stated that the static yield stress and the structural build-up have an optimum value in terms of the effect on IBS of 3DPC mixtures. On the other hand, studies indicating that the IBS of 3DPC mixtures depends on surface moisture of the layers were also encountered.Publication Effect of water-reducing admixtures having hybrid silicon air-entraining surfactants on some properties of concrete mixtures(Asce-Amer Soc Civil Engineers, 2022-09-01) Emin, Ayvaz; Özen, Süleyman; Mardani-Ağhabağlou, Ali; Ünlu, Ayda; Kapti, Tolga; Emin, Ayvaz; MARDANİ, ALİ; Bursa Uludağ Üniversitesi/Mühendislik Fakültesi.; Bursa Uludağ Üniversitesi/Mühendislik Fakültesi/İnşaat Mühendisliği Bölümü.; 0000-0003-0326-5015; GNY-1454-2022; C-7860-2015In order to improve the fresh properties and freeze-thaw resistance of cementitious systems, water-reducing and air-entraining admixtures are actively used in concrete mixtures. Generally, these mentioned admixtures are added to concrete mixtures as two separate admixtures. In this case, when the properties/compositions of one of the admixtures change, compatibility problems of admixtures may occur with each other or with the cement, and the fresh/hardened properties of the concrete may be adversely affected. In this study, a modified water-reducing admixture with both fluidity and air-entraining properties was produced. The utilization effect of high-range water-reducing admixtures (HRWR) having different ethylene oxide/propylene oxide (EO/PO)-based air-entraining surfactants (AES) on some properties of concrete mixtures was investigated. For this purpose, firstly, hybrid silicone AESs with a silicon content of 20%, 33%, and 38.5% were supplied. Then, HRWRs containing seven different AES were produced by using substitution and synthesis methods. In HRWRs produced by the substitution method, 3 and 5 wt. % of HRWR were substituted with EO/PO-based hybrid silicon AES. In the other method, EO/PO-based hybrid silicon air-entraining macromonomers were bonded to the HRWR at ratios of 1, 3, and 5 wt. % during its synthesis process. Replacing HRWR with hybrid silicone AESs increased admixture demand to provide the target slump value in concrete mixtures. Utilization of AESs containing 20% and 33% silicon in HRWR by the substitution method positively affected the permeability and compressive strength of concrete mixtures, while the rise of this ratio to 38.5% by using the synthesis method did not affect them significantly. The presence of surfactant with 20% silicon in 3% and 5% of the admixture and with 33% silicon in 5% of the admixture positively affected frost resistance of concrete mixtures. However, the use of surfactants with 33% silicon content in 3% of the admixture and 38.5% silicon in 1%, 3%, and 5% of the admixture showed a negative effect on the frost resistance of the mixtures.Publication Single and multi effects of polycarboxylate main and side chain lengths on setting time, viscosity, and yield stress of cementitious mixtures containing fly ash(Asce-Amer Soc Civil Engineers, 2023-07-01) Altun, Muhammet Gökhan; Özen, Süleyman; Karakuzu, Kemal; Mardani, Ali; Ramyar, Kambiz; Karakuzu, Kemal; MARDANİ, ALİ; Bursa Uludağ Üniversitesi/Mühendislik Fakültesi/İnşaat Mühendisliği Bölümü.; 0000-0003-0326-5015 ; GBH-3020-2022; C-7860-2015In this study, polycarboxylate polymers having different main chain lengths, side chain lengths, and main chain and side-chain lengths at constant molecular weight were synthesized. Cementitious mixtures with 0%, 15%, 30%, and 45% fly ash substitution levels were tested with polycarboxylate based admixtures (PCEs). As the main and side chain length of the PCE increased up to a certain value, regardless of the fly ash content, the fluidity of the mixtures was positively affected. However, after a certain length, both the electrostatic and steric effects of the PCE decreased, as the polymers intercalated and flocculated, adversely affecting the flow properties of the mixtures. Regardless of the PCE structure, the use of fly ash adversely affected the setting times and rheological properties of the mixtures.Publication Effect of waste binder material usage rate on thixotropic behaviour of cementitious systems(Elsevier Sci Ltd, 2023-09-03) Biricik, Öznur; AYTEKİN TÜRKOĞLU, BURCU; BİRİCİK, ÖZNUR; Aytekin, Burcu; MARDANİ, ALİ; Mardani, Ali; Bursa Uludağ Üniversitesi/Mühendislik Fakültesi/İnşaat Mühendisliği Bölümü.; 0000-0003-0326-5015; C-7860-2015; JPK-8822-2023In order to investigate the feasibility of using waste as an alternative binder in cement-based materials, the effects of using recycled concrete powder (RCP), glass powder (GP), marble powder (MP), and limestone powder (LP) in place of portland cement on the rheological and fresh characteristics of cementitious systems were determined. In this regard, the influence of the utilization of waste materials and the substitution ratio (25% and 35%) on the parameters of the cement paste mixtures that change over time, such as setting time, Marsh-funnel flow time, mini-slump value, viscosity, and dynamic yield stress (DYS), were determined. The effect of 4 different type waste powder materials on the rheology and thixotropy of cementitious systems was investigated using two different methods (loop and constant shear strain rate methods). In order to reduce cement consumption, the effect of the use of waste powder materials on the time-dependent behavior of cementitious systems has been examined, and important results have been obtained for cases (such as producing 3D concrete or self compacting concrete) where time-dependent consistency change is important. It was determined that replacing RCP and GP enhanced the DYS values while replacing MP and LP decreased them. In this context, it was understood that regardless of time, MP and LP promote flowability, whereas RCP and GP diminish flowability. RCP35 had the greatest Ithix_shr and Ithix_vis values at the 20th minute, whereas MP and LP-containing mixtures had the lowest values. The mixtures with the highest and lowest thixotropic degrees were RCP35 and LP35, respectively.Publication Research on modeling the thixotropic properties of cementitious systems using regression methods in machine learning(Elsevier Sci Ltd, 2023-12-28) Şahin, Hatice Gizem; Altun, Öznur Biricik; Eser, Murat; Bilgin, Metin; BİLGİN, METİN; Mardani, Ali; MARDANİ, ALİ; Bursa Uludağ Üniversitesi/Mühendislik Fakültesi/İnşaat Mühendisliği Bölümü.; Bursa Uludağ Üniversitesi/Mühendislik Fakültesi/Bilgisayar Mühendisliği Bölümü.; 0000-0002-8915-879X; 0000-0003-0326-5015; C-7860-2015; AAL-2592-2020; JPK-8822-2023; IAQ-9713-2023; AAE-2420-2022; KUD-7264-2024In this study, the rheological properties of cementitious systems were investigated through modeling studies on structural build-up and breakdown area. The area values were calculated using Herschel Bulkley analysis and hysteresis area method. The properties were examined by varying the composition of the cementitious system (cement fineness, C4AF, C3S, C2S, C3A, equivalent alkali and metakaolin ratio) and changes made in the rheological measurement processes (applied shear rate, maximum shear rate and duration). For this purpose, cement paste mixtures were prepared by substituting metakaolin at four different ratios (3%, 6%, 9%, and 12%) into cements with varying C3A content (2.13, 3.60, 6.82, 9.05%). The modeling study of the obtained results was conducted using three different learning methods: Linear Regression Analysis (LR), AdaBoost, and K Nearest Neighbor (KNN), encompassing machine learning and ensemble learning techniques. It was determined that the most dominant parameter affecting the rheology and thixotropic properties of the mixtures is the metakaolin usage ratio. The pre-shear rate was dominant over the duration and maximum shear rate parameters. Effect of the C3A content on dynamic yield stress and viscosity becomes more pronounced with an increase in the applied shear rate. The KNN method has yielded the best results in all experimental modeling studies. Euclidean distance criterion was used in the KNN method. Although the AdaBoost method obtained results close to the KNN method, the opposite situation was observed depending on the number of data. Logcosh, MAE and RMSE metrics were used to evaluate the experimental results. When the results for 3 different metrics in all modeling studies were examined, the success order of the metrics was found to be Logcosh, MAE and RMSE.Publication Review of research on designing methods and properties of roller compacted concrete mixtures(Pamukkale Üniversitesi, 2020-01-01) Mardani-Ağhabağlou, Ali; Bayqra, Sultan Hüsein; Özen, Süleyman; Altun, Muhammet Gökhan; Faqiri, Zia Ahmad; Ramyar, Kambiz; MARDANİ, ALİ; Bayqra, Sultan Hüsein; Altun, Muhammet Gökhan; Faqiri, Zia Ahmad; Bursa Uludağ Üniversitesi/Mühendislik Fakültesi/İnşaat Mühendisliği Bölümü.; 0000-0003-0326-5015; 0000-0003-2200-2691; AAJ-6415-2021; C-7860-2015; CDR-7456-2022; CBF-4437-2022; COI-3623-2022Roller compacted concrete (RCC) has been widely preferred in the world recently due to its rapid production rate, low cost and good durability compared to those of the traditional concrete. Having different production techniques from conventional concrete, RCC is used in many areas such as factories, oil stations, airports, industrial floor coverings, roads and dams. There are several methods for the proportioning of RCC mixtures, among which maximum density method is the most preferred one. In this study, the methods of designing of RCC mixtures are explained with an emphasis on the maximum density method. In addition, the previous studies on the RCC mixtures designed with the maximum density method are reviewed and suggestions are made for the future researches.
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