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Effect of magnetic water on properties of slag-based geopolymer composites incorporating ceramic tile waste from construction and demolition waste

Sevim Ozer, Alakara Erdinc Halis, Demir Ilhami, Bayer I. Raci

Archives of Civil and Mechanical Engineering

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2023

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Vol. 23, no. 2

art. no. e107, 2023

EN

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 °C. Ultrasonic pulse velocity (Upv), flexural strength (ffs), and compressive strength (fcs) 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 ℃ 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 ℃ 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, Upv, ffs, and fcs 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, Upv, ffs, and fcs 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, Upv, ffs, and fcs 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.

2

Influence of freeze–thaw cycling on properties of cementitious systems doped with fly ash having optimized particle size distribution

Demir Ilhami, Filazi Ahmet, Sevim Ozer, Simsek Osman

Archives of Civil and Mechanical Engineering

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2022

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Vol. 22, no. 4

art. no. e189, 2022

EN

In this study, the particle size distribution (PSD) of class F and C fly ash (FA) was optimized using theory of the Fuller-Thompson. After defining the optimal size distribution, the distribution modulus (q) of 0.4 yields the best mechanical property results. The freeze–thaw up to 300 cycles on mechanical and permeability properties of 90-day cementitious composites incorporating optimized class F and C fly ash (5, 10, 15, 20, 25, and 30% by weight of cement) were investigated. Optimized FA has improved the mechanical and permeability properties of cementitious composites under freeze–thaw cycling by ensuring a better filler effect. The cementitious composite mortars with 20% optimized class C fly ash and class F fly ash replacement yielded high compactness and better mechanical properties than the control cementitious composite mortars without any fly ash replacement after 90 days. Finding the best particle size distribution of FA providing high compactness will save cement, reduce the carbon dioxide (CO2) emission that pollutes the environment in cement production, and contribute to the economy and environment.

3

Effects of the sole or combined use of chemical admixtures on properties of self-compacting concrete

Sevim Ozer, Kalkan Ilker, Demir Ilhami, Akgüngör Ali Payıdar

Archives of Civil and Mechanical Engineering

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2021

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Vol. 21, no. 4

263--276

EN

Chemical additives are very important in determining the behavioral characteristics of self-compacting concrete. For this reason, determining the building materials that make up the chemical structure of self-compacting concrete and the interactions of these materials is of great importance. The present study pertains to the effects of the use of different chemical admixtures (high-range water-reducing, i.e., superplasticizer, hydration accelerating, air-entraining, shrinkage reducing, and hydration heat reducing admixtures) on the fresh and hardened properties of self-compacting concrete. The influence of using a single one or a hybrid combination of the air-entraining, hydration-accelerating, heat-reducing, and shrinkage-reducing admixtures on the mechanical properties of fresh and hardened SCC was investigated through a set of tests. For this purpose, sixteen different SCC mixtures with different combinations of chemical additives were prepared and tested. The properties of fresh concrete were examined as well as the compressive and tensile strengths of the mixtures. SCC mixtures with shrinkage-reducing admixtures were evaluated in terms of shrinkage development. The effect of the use of admixtures was found to be more pronounced on the early-age concrete strength. The use of any type of additive in addition to the shrinkage-reducing admixture increased the speed of flow of fresh concrete.

4

Enhancement on mechanical and durability performances of binary cementitious systems by optimizing particle size distribution of fly ash

Filazi Ahmet, Demir Ilhami, Sevim Ozer

Archives of Civil and Mechanical Engineering

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2020

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Vol. 20, no. 2

410--422

EN

Fly ash is a well-known supplementary cementitious material that is the by-product of coal-fired thermal power plants. The contribution of fly ash to the enhancement of the mechanical and durability properties of cementitious materials has been documented in concrete technology for many years. In this study, to allow superior mechanical and durability properties, fly ash-based mixtures have been produced after optimization of particle size distribution (PSD) of Class F and Class C fly ash according to the formula of Fuller–Thompson. Different distribution modulus values ranging from 0.3 to 0.6 were used to achieve ideal PSD in accordance with the Fuller–Thompson equation. 30% of F- and C-class fly ash by weight of cement were used to replace with cement in cementitious composites by optimizing PSD with help of air jet sieve. The recommended optimization technique improved the 7-, 28- and 90-day compressive and flexural strength results of mortars. Compressive and flexural strength tests and rapid chloride permeability test of cement-based systems incorporating fly ash up to 15% replacement ratio with optimized PSD at 90-days exhibited better results than those of plain samples owing to the filler effect.