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- MakaleYalnız künye2026Scopus SJRQ2Drying Shrinkage and Microstructural Properties of Geopolymers Including Steel and Iron Particles
Gulmez, Nihan; Kockal, Niyazi Ugur
Geopolymer mortars show significantly higher shrinkage than normal Portland cement mortars. So, one of the most important disadvantages of these promising alternative binding materials for their wider applications is the cracking occurring by shrinkage. Different inserts and fibers are used in fresh mixtures in order to control drying shrinkage cracks and to provide mechanical capacity. The aim of this study is to investigate the effectiveness of using both metal particles (iron particles) and metallic fibers (steel particles) in geopolymer composites to reduce drying shrinkage. In addition, microstructural properties of composites were determined by scanning electron microscopy (SEM) and X-ray diffraction (XRD) analyses and causes of shrinkage were investigated in detail. Mixtures containing 20% silica fume have 38.4% lower drying shrinkage than slag-based mixtures. In slag-based composites, decreases in drying shrinkage were found as 18.8% and 49.1% when adding 10% iron particles or 10% steel particles compared to metal-free composites.
- MakaleAçık Erişim2026Scopus SJRQ2Experimental and numerical analysis of ceramic fiber geopolymer concrete under blast effect
Dalğıç, Aras; Yılmazer Polat, Berivan; Savaş, Sedat
This study employs both experimental and numerical methods to investigate the blast resistance of ceramic fiber-reinforced geopolymer concrete (CFGC), a cement-free material often referred to as green concrete due to its environmentally friendly nature compared to Portland cement concrete (PCC). Geopolymer concrete specimens, formulated with ground granulated blast furnace slag, silica fume, and varying proportions of ceramic fibers, were subjected to blast tests using 50, 100, 150, 200, and 250 grams of trinitroglycerin (TNG). A standard PCC specimen was utilized as a control. The results demonstrate that the incorporation of 10% ceramic fibers significantly enhances the blast resistance of the geopolymer concrete, reducing crater diameters by up to 20% compared to conventional PCC. Furthermore, the finite element model developed in ANSYS Workbench exhibits a strong correlation with the experimental data, validating the predictive capability of the numerical simulations. Overall, this research highlights the immense potential of CFGC as a sustainable, highly durable alternative for structures exposed to blast loads.
- MakaleAçık Erişim2025Scopus SJRQ1Evaluating the high-temperature resistance of self-compacting mortar incorporating waste andesite powder as a mineral admixture
Karataş, Mehmet; Bozcan, Emre; Dener, Murat
Significant amounts of waste material are generated at various stages of andesite stone processing, including mining, cutting, and polishing. Despite this, limited research has been conducted on the potential use of waste andesite powder (WAP) as a mineral admixture. The impact of WAP on the high-temperature resistance of cement-based composites remains largely unexplored. This study aims to evaluate the benefits of incorporating WAP as a partial substitute for Portland cement. Self-compacting mortars (SCMs) with varying WAP replacement rates (5%–30%) were produced and subjected to temperatures of 300°C, 600°C, and 900°C. Additionally, ternary mixtures of WAP and silica fume were produced for comparative analysis. The results showed that SCMs containing up to 10% WAP exhibited higher 90-day compressive strength compared to the control sample. Furthermore, WAP inclusion improved high-temperature resistance, and the use of WAP at higher replacement rates was feasible when combined with mineral admixtures possessing high pozzolanic activity, such as silica fume.
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İncele - MakaleYalnız künye2025Scopus SJRQ1Mechanical, durability and microstructure properties of eco-friendly self-compacting mortars with addition of volcanic scoria, silica fume and boron waste as cement replacement
Şahin Yön, Merve
The objective of this experimental study is to investigate the mechanical and durability performances of self-compacting mortars containing industrial waste and natural stone to develop an environmentally friendly mortar. Binary series of boron waste (B), silica fume (S) and volcanic scoria (V) were formed by substituting up to 95 % by weight with Portland cement, and ternary series were formed by substituting up to 80 % by weight with Portland cement. A total of 14 mixtures and one reference mixture (R) were improved for the purpose of investigating the workability, mechanical strength and durability properties of self-compacting mortar with different binder compositions. Samples of 40x40x160 mm were produced to evaluate mechanical properties and freeze-thaw effect, 100x100x100 mm for abrasion testing and 50x50x50 mm to determine physical properties. Additionally, SEM/EDS and XRD analyses were performed to determine the microstructural characteristics of the mixtures formed. The test results demonstrated that the sole replacement of boron waste with Portland cement resulted in enhanced fluidity. Nonetheless, the 90-day compressive strengths of the S10V20 and B5S10V5 mixtures exhibited increases of 7.47 % and 5.57 %, respectively, relative to the reference, whilst the B15 series saw a 52.5 % reduction, marking the lowest 90-day compressive strength compared to the reference sample. When the freeze-thaw effect was assessed after 136 cycles, the compressive strength diminished by 8.57 %, 13.1 %, 4.13 %, 7.28 %, 6.22 %, 24.77 %, and 48.1 % in the R, B5, V5, V10, V15, B5S10V5, B5S10V10, and B5S10V15 samples, respectively. Among the samples subjected to abrasion tests, a loss of 6.5 per thousand occurred in the mass of the reference sample at the end of 6 minutes, while a loss of 11 per thousand occurred in the binary mixture containing 5 % B, which had the highest abrasion.
AtıfScopus16WoS14OpenAlex16İncele - MakaleAçık Erişim2024Scopus SJRQ2The Behavior of Ceramic Fiber Geopolymer Concrete under the Effect of High Temperature
Dalğıç, Aras; Yılmazer Polat, Berivan
Geopolymer concrete (GC), also known as green concrete, contains slag, silica fume, and fly ash as binders. The absence of cement in concrete is critical to protect the world from the environmental impacts of cement production. In addition, exposure to high temperatures is a critical parameter that causes loss of strength in concrete. In this study, Geopolymer concrete samples were prepared with 10 different samples containing different proportions of slag, silica fume, and porous ash and subjected to various physical, mechanical, and optical tests. The sample (GS90) with optimum workability and compressive strength, which also showed high performance in water absorption, freeze-thaw, and UPV tests, was used in high-temperature tests. Portland cement concrete (PCC) was used as a control sample. This study investigated the effect of high temperatures on the physical and mechanical properties of fiber-free GCs containing 2%, 5%, and 10% by volume of ceramic fibers. Therefore, fiber-reinforced, fiber-free, and PCC specimens were subjected to high-temperature tests at 100, 300, 600, and 900 °C. As a result of the observation of crack growth, color changes, and compressive strength parameters in the samples subjected to high-temperature tests, the thermal resistance of the 10% ceramic fiber geopolymer concrete sample was 2.5% higher than other samples. There is no study in the literature that examines the behavior of ceramic fiber-reinforced geopolymer concrete at high temperatures. This research revealed an important finding by proving that ceramic fiber reinforcement increases the compressive strength of geopolymer concretes at a remarkable rate after high-temperature impact.
AtıfScopus8WoS10OpenAlex8İncele - MakaleYayıncıda açık erişim2023Scopus SJRQ1Evaluation of the effect of silica fume on the fresh, mechanical and durability properties of self-compacting concrete produced by using waste rubber as fine aggregate
Etli, Serkan
The supply of sand, which is obtained by disposing of natural resources for the purpose of concrete production and in accordance with production standards, is increasing rapidly and therefore its amount is rapidly depleted. A study is presented that aims to reduce the aggregate content by using this waste tire aggregate (WTA) in the construction industry, and thus, a sustainable production and conservation of nature is the basis. The water/binder ratio used in the study is kept constant as 0.39 and the binder dosage as 550 kg/m3. WTA and SF are replaced with sand and cement at the ratios of 5%, 10% and 15% by volume, and 5% and %15 b y weight, respectively. The fresh (slump flow, V-funnel, and L-box) and hardened (axial compression, splitting tensile strength, flexural tensile strength, diagonal tensile strength, and modulus of elasticity, chlorine penetration and sorptivity) properties of self-compacting concrete (SCC) mixtures produced in this way are evaluated. For the mechanical and durability tests, a total of approximately 500 SCC (100 × 100 × 500 mm: prism, 100 × 100 × 100 mm: cube and 100 × 200 mm: cylindrical) samples are produced. The mechanical experiments of SCC were carried out at 28-, 56- and 90-days age. The test results have shown that WTA substitute concrete, which can be used in terms of civil engineering in terms of all these features, has shown that it has sufficient performance.
AtıfScopus51WoS43OpenAlex55İncele - MakaleYalnız künye2023Scopus SJRQ2Engineering Properties of Geopolymer Mortars Containing Industrial Steel Shavings
Gülmez, Nihan; Koçkal, Niyazi Uğur
The purpose of using waste materials is to prevent the unnecessary use of resources and to reduce the amount of waste. Geopolymer, developed as an alternative to cementitious materials, prevents the depletion of natural resources and saves a large amount of energy. This paper presents the effect of waste steel shavings on the improvement of physical and mechanical properties of geopolymer mortars. For this purpose, geopolymer mortars were produced by using two binder types [slag (BFSb) and silica fume] as well as steel shavings in five different replacement percentages (0%, 2.5%, 5%, 7.5% and 10%) by volume instead of aggregate. A series of experiments on geopolymer mortars were carried out to determine properties such as bulk density, water absorption, apparent porosity, sorptivity coefficient, splitting tensile strength, flexural strength and compressive strength. Results showed that steel shavings recovered from metal processing and forming sector were highly effective at improving engineering properties of geopolymer mortars. Furthermore, although replacement of 20% by volume of BFSb with silica fume improved properties of geopolymer mortar, it was observed that the use of silica fume at higher ratios reduced mechanical properties by increasing porosity and sorptivity of BFSb-based geopolymer mortars.
AtıfScopus1OpenAlex1İncele - MakaleYalnız künye2023Scopus SJRQ2Computer-aided Optimization of Geopolymer Mortars
Gülmez, Nihan; Koçkal, Niyazi Uğur
The optimum mix design of geopolymers involves the purpose of determining which mixture will have high engineering properties without compromising the importance of each variable. This experimental study aimed to investigate the effects of some critical geopolymer mixture parameters on engineering properties by using historical data design in response surface methodology (RSM). Statistical models were developed between factors (binder and aggregate content, curing conditions and aggregate type) and their response surfaces (oven dry (OD) bulk density, water absorption, compressive strength and flexural strength). The final mathematical models for the response surfaces were constructed in terms of coded factors defined as dimensionless. In addition, a multipurpose optimization technique was used to achieve the desired design with the desired maximum strength.
- MakaleYalnız künye2021Scopus SJRQ3Effects of iron powder on properties of geopolymers subjected to different curing regimes
Gulmez, Nihan; Kockal, Niyazi Ugur
Silica fume, slag and iron powder are by-products from various industries. In parallel with development of industrial technology, it is also known that these by-products which cause rapid pollution of the environment are also harmful to human health because they are easily respirable. For this reason, a series of experiments were carried out to determine physical and mechanical properties on samples prepared using different blend designs to examine the effect of factors such as curing conditions, binder type and waste iron powder content. Percentages of iron powder added to replace the aggregate are 10%, 20%, 30% and 40% by volume of slag aggregate. It was observed that the substitution of 30% by volume iron powder instead of slag in geopolymer mortars is the most effective in increasing splitting tensile strength. For 40% partial replacement of fine aggregates with iron powder, increases in compressive strength and flexural strength of slag-based mortars were 7.2% and 43.4%, respectively, compared to mortar without iron powder at 60°C curing conditions.
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