Yazar "Demircan, Rueya Kilic" seçeneğine göre listele

Listeleniyor 1 - 2 / 2
  • [ X ]
    Öğe
    Effect of waste COVID-19 face masks on self-compacting high-strength mortars exposed to elevated temperature
    (Elsevier, 2023) Durmus, Goekhan; Celik, Damla Nur; Demircan, Rueya Kilic; Kaplan, Goekhan
    During the pandemic, it becomes customary to wear a disposable surgical (face) mask (SM) to guard against coronavirus illness 19 (COVID-19). However, because existing disposal procedures (i.e., incinera-tion and reclamation) emit hazardous substances, vast generations of contaminated surgical masks pose an environmental risk. Therefore, many studies are currently being carried out worldwide to dispose of SM. The easiest and cheapest of these methods is the disposal of SMs in cement-based composites. This study cut waste SMs to macro size and used them in cement-based composites such as polypropylene fiber. The elevated temperature resistance of cement-based composites decreases as their compressive strength rises. Low-melting materials like polypropylene fiber are utilized to improve the high -temperature resistance of cement-based composites. Therefore, SM with a low melting temperature was used in the design of the mixtures. SM was added to the mix at rates of 0.3, 0.5, 0.8, and 1 by weight of cement. As the SM ratio increased, the workability of the mixtures decreased. Water absorption and apparent porosity increased as SM reduced the workability of composites. The mixes' 28-day compres-sive strength ranges from 36.6 to 79.4 MPa. It was observed that flexural strength raised in some mix-tures when SM was used. In the mixes using 0.5 % SM, about 40 MPa compressive strength was obtained after 800 degrees C. Additionally, SEM images showed that SM changed into microfibre during mixing. As a result, it has been determined that SM can be used at low rates to increase the elevated temperature resistance of cement-based composites. (c) 2022 THE AUTHORS. Published by Elsevier BV on behalf of Faculty of Engineering, Ain Shams Uni-versity. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).
  • [ X ]
    Öğe
    The engineering properties of high strength mortars incorporating juniper seed ash calcined at different temperatures: Comparison with other SCMs
    (Elsevier, 2023) Celik, Damla Nur; Demircan, Rueya Kilic; Shi, Jinyan; Kaplan, Gokhan; Durmus, Gokhan
    The juniper tree is widely distributed in Europe, but its fruit (juniper seed ash, JSA) is not well utilized, and most of it is naturally degraded. This study provides an efficient way to recycle JSA by calcining it at different temperatures (350 and 500 degrees C) to obtain supplementary cementitious materials (SCMs). The feasibility of using JSA to modify mortar is discussed from technical, economic and environmental aspects, and it is compared with conventional SCMs. The results show that the incorporation of JSA significantly improves the flowability of the mixture and reduces the unit weight of the hardened sample compared to conventional SCMs. However, JSAmodified mortars exhibit higher apparent porosity and water absorption due to the low pozzolanic reactivity and high porosity of JSA, but JSA outperforms RHA for high-content (12.5%-17.5%) SCM-modified mortars. The incorporation of a small amount (7.5%) of JSA reduces the compressive strength of the mortar, but the compressive strength of the mortar mixed with JSA-350 calcined at 350 degrees C is slightly higher than or similar to that of the traditional SCM-modified mortar. Since the flexural strength is more sensitive to the microstructure, the incorporation of JSA makes it significantly lower. In addition, the low reactivity and high porosity of JSA also lead to an increase in the 91-d capillary water absorption and a decrease in the electrical resistivity of the mortar samples. Meanwhile, the pozzolanic reaction of traditional SCM consumes Ca2+ ions and OH- to increase the electrical resistance of the mortar, while the alkalinity of JSA increases the content of OH and reduces the electrical resistance of the mortar. In addition, using JSA to modify high-strength mortar also reduces its cost and carbon footprint, which indicates that recycling juniper seeds in high-strength mortar is a sustainable strategy.