Browsing by Author "Atiş, Cengiz Duran"

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Characterizing boron-enhanced one-part alkaline-activated mortars: Mechanical properties, microstructure and environmental impacts
(ELSEVIER, 2024) Örklemez, Ezgi; İlkentapar, Serhan; Durak, Ugur; Gülçimen, Sedat; Uzal, Niğmet; Uzal, Burak; Karahan, Okan; Atiş, Cengiz Duran; 0000-0002-8967-3484; 0000-0002-3810-7263; AGÜ, Mühendislik Fakültesi, İnşaat Mühendisliği Bölümü; Gülçimen, Sedat; Uzal, Niğmet; Uzal, Burak
Since alkali activators negatively effect the environmental impact assessment, it is necessary to develop the alternative activators from natural sources with low environmental impact. Therefore, in this study, the usage of boron refined products colemanite, ulexite and boron pentahydrate as activators in slag-based alkali-activated mortar systems was investigated in detail. Flexural and compressive strength tests, isothermal calorimetry measurement, thermogravimetric and differential thermal analysis, inductively coupled plasma mass spectrometry analysis, field emission scanning electron microscopy, and energy dispersive analysis and elemental mapping and X-ray diffraction analysis were carried out on the samples. In addition, sample production was subjected to life cycle analysis (LCA) with a cradle-to-gate approach using two different transportation scenarios. According to the results obtained, it was determined that colemanite, ulexite and boron penta hydrate, when used in optimum proportions, had a positive effect on strength (up to increase 40% compressive strength by 20% ulexite replacement) and could be used as an activator in slag-based alkali-activated systems. The positive results obtained in strength as a result of using boron-refined products are also supported by other test results conducted within the scope of the study. Furthermore, according to the LCA results, it was observed that there was a significant decrease in global warming potential with the substitution of 20% colemanite, ulexite or boron pentahydrate as activators, not only compared to the reference sample but also traditional cementitious systems.
Comparison of Mechanical and Physical Properties of Screed with and without Expanded Polystyrene (EPS) Particles
(YILDIZ TEKNİK ÜNİVERSİTESİ, 2022) Kılıç, Fikret Merih; Yorulmaz, Hediye; Özuzun, Sümeyye; Durak, Uğur; İlkentapar, Serhan; Karahan, Okan; Atiş, Cengiz Duran; 0000-0002-1015-4308; AGÜ, Mühendislik Fakültesi, İnşaat Mühendisliği Bölümü; Yorulmaz, Hediye
In this study, in order to observe the mechanical and physical properties of ordinary screed, sandy-lightweight screed and lightweight screed samples, expanded polystyrene (EPS) was used as fine aggregate and lightweight screed systems were produced by replacing sand at 100%, 50% and 0%. Samples of cement dosages of 250, 300, 350 kg/m3 were produced for lightweight screeds, sandy-lightweight screeds and ordinary screeds. Unit weight, water absorption capacity, flexural strength, compressive strength, fire resistance, abrasion and thermal conductivity tests were performed on the produced screed systems. As a result of the research, it was determined that as EPS ratio increases in screed system; unit weights decreased, water absorption rates increased. Besides, the flexural and compressive strengths, fire and abrasion resistance are also decreased. However, it was observed that the thermal conductivity coefficient reduced with the increment of EPS particles in the screed. In normal, sandy-lightweight and lightweight screeds, it was determined that as the cement dosage increased; the unit weights, flexural and compressive strengths, fire and abrasion resistance increased, water absorption capacity and the thermal conductivity coefficient decreased.
Effect of Nano-SiO2 on Strength and Hydration Characteristics of Ternary Cementitious Systems
(Institute for Ionics, 2023) Yorulmaz, Hediye; Uzal, Burak; Karahan, Okan; Durak, Uğur; İlkentapar, Serhan; Atiş, Cengiz Duran; 0000-0002-1015-4308; 0000-0002-3810-7263; AGÜ, Mühendislik Fakültesi, İnşaat Mühendisliği Bölümü; Yorulmaz, Hediye; Uzal, Burak
This paper shows results of laboratory study on the effects of nano-SiO2 on Portland cement-fly ash systems. It is aimed to improve performance of fly ash–cement systems, particularly at early age, with the inclusion of nano-SiO2. In order to observe the effects of nano-SiO2 particles on the strength and hydration kinetics of fly ash blended cementitious systems, binary and ternary systems were prepared by adding 0.25–1.5% nano-SiO2 by weight of blended cements. Workability, setting time, water absorption capacity, fire resistance, compressive strength and isothermal calorimeter tests were conducted on the cementitious systems. The results indicate that increasing quantity of fly ash increased workability, setting time, water absorption capacity of cementitious systems, whereas the increasing quantity of nano-SiO2 reduced these values. Significant increment in compressive strength were observed, especially at early ages of fly ash–cement systems with nano-SiO2 addition, compared to fly ash added systems, which may compensate for the decrease in compressive strength caused by fly ash. NanoSiO2 addition accelerated hydration reactions at early age. By partially eliminating the negative effects of fly ash with nano-SiO2, high rates of fly ash can be used in cementitious systems, thus forming more sustainable systems.
Effects of dry particle coating with nano- and microparticles on early compressive strength of portland cement pastes
(Tulpar Academic Publisher, 2021) Yorulmaz, Hediye; Uzal, Burak; Özuzun, Sümeyye; İlkentapar, Serhan; Durak, Uğur; Karahan, Okan; Atiş, Cengiz Duran; 0000-0002-1015-4308; 0000-0001-6892-6692; 0000-0002-3810-7263; 0000-0002-9932-2899; 0000-0001-7970-1982; 0000-0003-3459-329X; 0000-0003-2731-3886; AGÜ, Mühendislik Fakültesi, İnşaat Mühendisliği Bölümü; Yorulmaz, Hediye; Uzal, Burak
It is known that nano-and microparticles have been very popular in recent years since their advantages. However, due to the very small size of such materials, they have very high tendency to agglomeration particularly for nanoparticles. Therefore, it is critical that they are properly distributed in the system to which they are added. This paper investigated the effects of dry particle coating with nano-and microparticles to solve the agglomeration problem. For a clear evaluation, paste samples were preferred to detemine the compressive strength. Nano-SiO2 and nano-CaCO3, micro-CaCO3 and micro-SiO2, also known as silica fume, were selected as particulate additives. It was studied by the addition of various percentages (0.3, 0.7, 1, 2, 3 and 5%) of nano-and microparticles in cementitious systems, replacing cement by weight with and without dry particle coating. Dry particle coating was made by using a high-speed paddle mixer. Portland cement and additive particles were mixed at 1500 rpm for 30 seconds in high-speed powder mixer designed for this purpose. The 3-day compressive strength of the cement-based samples to which particles were added at the specified rates was determined and the effect of the dry particle coating on the early strength was investigated. According to the results, it was observed that the production of paste with the dry particle coating technique gave higher compressive strength compared to the production of paste directly in early period. Especially with dry particle coating, compressive strength increased more than 100% in paste samples containing 0.3% nano-SiO2 compared to direct addition without coating.
The influence of cement kiln dust on strength and durability properties of cement-based systems
(SPRINGER, 2022) Hakkomaz, Hadiye; Yorulmaz, Hediye; Durak, Uğur; İlkentapar, Serhan; Karahan, Okan; Atiş, Cengiz Duran; 0000-0002-1015-4308; AGÜ, Mühendislik Fakültesi, İnşaat Mühendisliği Bölümü; Yorulmaz, Hediye
There are very few studies in the literature on the usage of CKD in cementitious systems. This article presents the laboratory study results on the infuence of cement kiln dust (CKD) on the properties of mortar made with cement kiln dust and Portland cement. The article aims to prevent CKD’s (known as a hazardous waste product) damage to nature by utilizing CKD in cementitious systems and contributing to sustainability by reducing cement amount in the cementitious system. For this purpose, 5%, 10%, 15%, and 20% of CKD were replaced with cement and binary cementitious systems were formed. For all mortar mixes, the water/binder ratio was kept constant at 0.5, and the sand/binder ratio was 3. Workability, dry unit weight, water absorption ratio and porosity, fexural strength, compressive strength, abrasion, carbonation, and high-temperature resistance tests were performed on the mortar specimens. Based on the results of laboratory work, it was observed that the replacement of CKD with cement reduces the workability of fresh mortar. Compressive and fexural strengths of CKD-added mixtures were found to be equivalent or insignifcantly lower than that of the control sample. The addition of CKD had a negligible efect on water absorption and porosity of samples. Besides, the residual compressive strength determined after the elevated temperature test for the sample made with CKD were found to be equivalent or higher compared to the control sample. Present laboratory studies showed that utilization of CKD in cementitious mortar system is feasible in terms of testing conducted.