Browsing by Author "Memiş S."

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Artificial neural network estimation of the effect of varying curing conditions and cement type on hardened concrete properties
(2019-01-03) Kaplan G.; Yaprak H.; Memiş S.; Alnkaa A.
The use of mineral admixtures and industrial waste as a replacement for Portland cement is recognized widely for its energy efficiency along with reduced CO2 emissions. The use of materials such as fly ash, blast-furnace slag or limestone powder in concrete production makes this process a sustainable one. This study explored a number of hardened concrete properties, such as compressive strength, ultrasonic pulse velocity, dynamic elasticity modulus, water absorption and depth of penetration under varying curing conditions having produced concrete samples using Portland cement (PC), slag cement (SC) and limestone cement (LC). The samples were produced at 0.63 and 0.70 w/c (water/cement) ratios. Hardened concrete samples were then cured under three conditions, namely standard (W), open air (A) and sealed plastic bag (B). Although it was found that the early-age strength of slag cement was lower, it was improved significantly on 90th day. In terms of the effect of curing conditions on compressive strength, cure W offered the highest compressive strength, as expected, while cure A offered slightly lower compressive strength levels. An increase in the w/c ratio was found to have a negative impact on pozzolanic reactions, which resulted in poor hardened concrete properties. Furthermore, carbonation effect was found to have positive effects on some of the concrete properties, and it was observed to have improved the depth of water penetration. Moreover, it was possible to estimate the compressive strength with high precision using artificial neural networks (ANN). The values of the slopes of the regression lines for training, validating and testing datasets were 0.9881, 0.9885 and 0.9776, respectively. This indicates the high accuracy of the developed model as well as a good correlation between the predicted compressive strength values and the experimental (measured) ones.
Behavior of mortar samples with waste brick and ceramic under freeze-thaw effect
(2018-01-01) Memiş S.; Özkan I.G.M.; Yılmazoğlu M.U.; Kaplan G.; Yaprak H.
Increasing number of industrial facilities and population concentration in particular regions along with overconsumption are main reasons of the increased environmental pollution. It is a necessity to preserve available resources and to keep the waste in control in order to achieve a sustainable development goal. In recent years, concepts of waste management, recycling and sustainability have gained importance with regards to the construction industry. Today, approximately 35 billion tons of concrete is produced worldwide and 80% of this amount consists of aggregated manufactured using natural resources. A significant environmental impact is the case even for the production of cement, a binding agent for concrete, which accounts for 1 ton CO2 emission in order to produce 1 ton of cement. The main subject of this study is the production of a sustainable construction material with the use of ceramic instead of both aggregate and cement. Clay is defined as a common natural material with fine-grains, with layers and a high water absorption capacity. Ceramic products are construction materials which can replace cement generally in the form of artificial puzzolana. The main subject of this study is the use of the waste obtained from ceramic plants which produces ceramic products in mortars. Taguchi L9 array design was used as part of this experimental study. Water-binder ratio was set to 0.50 in the preparation of the mixes and natural aggregates were used. Aggregates were then replaced by pieces ceramic and brick at a percentage between 20 and 60% while cement was replaced by ceramic and brick powder at a percentage between 10 and 30%. The mixes were then subjected to freeze and thaw tests at 30, 60 and 90 cycles in accordance with ASTM C 666 standard. Dynamic modulus and mechanical properties of the mortars subjected to f-t effect were then identified. When the results of the tests were examined, it was found that the compressive strength at 7th and 28th days were decreased with the increase of the volume of ceramic and brick powder used while it was found that the use of ceramic and brick powder did not have a significant effect on the compressive strength at the 90th day. The use of ceramic and brick aggregate led to favorable results in terms of freeze-thaw resistance. Especially the use of 10% ceramic [(whiteware) CA] and 20% other ceramic [(brick) BA] aggregate in mortars subjected to 90 f-t cycles increased the dynamic modulus while similar results were found for the use of 5% ceramic powder and 10% brick powder in mortars subjected to 90 days of f-t cycles. This study shows that waste material obtained from ceramic and bricks industry can be repurposed in the construction industry.
INVESTIGATION AND TAGUCHI OPTIMIZATION OF FIRE RESISTANCE IN ULTRA-HIGH PERFORMANCE CONCRETE (UHPC) PRODUCED USING MINERAL ADDITIVES
(2022-01-01) Memiş S.; Ramroom A.A.
In this study, the effects of silica fume (SF), fly ash (FA) and granulated blast furnace slag (GBFS) on the design and fire resistance properties of ultra-high performance concrete (UHPC) were analyzed using the Taguchi L16 method. Samples were exposed to temperatures of 300 °C, 450 °C and 600 °C. The composition of the UHPC was: sand/binder ratio = 1, water/binder ratio = 0.19, Polycarboxylate superplasticizer (PCE) /binder ratio = 3.5%, pozzolanic (SF, FA and GBFS)/binder ratio = (0, 10, 15, 20)% and steel fibers = 1% by volume, and a Taguchi L16 program was prepared that consisted of 240 samples (40x40x160mm). The high-temperature properties of the UHPC samples were evaluated. Because several mixtures could withstand a temperature of 450 °C, it was determined that the losses were more effective when the highest temperature reached was greater than or equal to 600 °C, and the twelve mixtures are damaged by breaking them up. When the actual values obtained in the verification test were examined, it was determined that the results were sufficient for the compressive and flexural strength and physical properties of the concrete under various heating conditions and the Taguchi optimization was successfully implemented.
Investigation of the ideal mixing ratio and steel fiber additive in ultra high performance concrete (Uhpc)
(2020-01-01) Memiş S.; Ramroom A.A.
Ultra high performance concrete (UHPC) generally has low workability due to the fact that it is a material with low water/cement (w/c) ratio and contains fiber in it. Therefore, adding a superplasticizer (SP) in its production may be a solution, so that it can self-compress, but there may be an overdosing problem. This research, conducted in two stages to determine ideal UPHC mixture, consisted of the first stage involving the determination of the sand/binder (s/b) ratio and the two stages, which included the determination of the ideal steel fiber ratio. To achieve ultra-high performance, the w/c ratio was reduced to 0.2 and the steel fiber was increased to a maximum of 2%. The fresh and hardened properties of UPHC were examined, for better workability their flow diameters and also compressive strengths, flexural strengths, densities, water absorption rates, total voids were determined in UPHC mixtures. It has been determined that the maximum strength can reach about 110 MPa without steel fiber reinforcement, but 130-140 MPa strengths can be achieved if up to 2% steel fiber is added to the mixtures. It has been found that the strength of the UHPC is related to the s/b ratio and the fiber volume used and that the UHPCs can be obtained when the ideal ratios are taken into account.
Investigation of the use of waste mineral additives in ultra-high-performance concrete
(2023-01-01) Memiş S.; Ramroom A.A.
Performance, cost, and ecological assessment of fiber-reinforced high-performance mortar incorporating pumice powder and ground granulated blast furnace slag as partial cement replacement
(2024-10-15) Ifzaznah H.H.H.; Güllü A.; Memiş S.; Yaprak H.; Gencel O.; Ozbakkaloglu T.
Some durability properties of alkali activated materials (AAM) produced with ceramic powder and micro calcite
(2018-01-01) Memiş S.; Kaplan G.; Yaprak H.; Yilmazoğlu M.; Mütevvelli̇ Özkan I.
This study aims to produce alkali-activated materials (AAM) under different curing conditions using a ceramic powder (CP) instead of a blast furnace slag (BFS) and a micro calcite (McK) instead of a calcareous aggregate. The water/binder (W/B) ratios of the AAMs range from 0.30 - 0.42 and the sodium silicate (SS) ratios range from 15 - 60 %. They were subjected to curing process in 80°C water and in an oven, in the air, and with a chemical curing method. Consequently, it was observed that an increase in the ratios of SS and W/B and using 25 % McK with a spherical structure, increased the workability. An increase in the CP and McK usage ratios reduced the 28-day compressive strengths. Using the CP while designing the AAMs, which were exposed to sodium sulfate and sulfuric acid, reduced the losses in strength. Also, an increase in the CP ratio has a positive influence on the AAM as it increases the high-temperature endurance of the mortars. For conventional concrete, permeability in freeze-thaw resistance is an important factor for AAMs. Hence, using McK in AAMs increases the freeze-thaw resistance. Consequently, it was observed that using a CP up to 40 % influences the AAM positively.
Taguchi optimization of geopolymer concrete produced with rice husk ash and ceramic dust
(2022-03-01) Memiş S.; Bılal M.A.M.
Metakaolin, fly ash, and mostly granulated blast furnace slag (GBFS) are traditionally used in the production of geopolymer. This study, adding to the knowledge base on geopolymer concretes as an alternative to cement mixtures, explored an experimental approach that investigates the use of ceramic dust (CD) and rice husk ash (RHA) with high SiO content instead of GBFS in the production of geopolymers. For this purpose, instead of GBFS, RHA at proportions of 0, 5%, 10%, and 15% and CD at proportions of 0, 10%, 20%, and 30% were used in the production of geopolymer concrete. In addition, groups were determined with a Taguchi L16 matrix with NaOH (an important material in geopolymer production) at 12, 14, 16, and 18 molality. Varying combinations of flow diameter, density, porosity, and water absorption rate were used, and their performance under high temperatures in terms of compressive strength was evaluated. The use of RHA in geopolymer concretes produced using CD and RHA had a negative effect on the flow and water absorption rates. However, the use of CD had a positive effect, and geopolymer concretes with high density and porosity were obtained. In addition, it was determined that strengths > 70 MPa could only be obtained if 5–20% CD were used at 14–16 molality. The resistance of geopolymer concretes to high temperatures is lower than normal concretes. However, when comparing RHA and CD, it was determined that the use of CD would be more effective on geopolymer materials, and special measures should be taken at temperatures > 450 °C. Graphıcal abstract: [Figure not available: see fulltext.].
The Optimization of Calcareous Fly Ash-Added Cement Containing Grinding Aids and Strength-Improving Additives
(2018-01-01) Kaplan G.; Yildizel S.A.; Memiş S.; Öztürk A.U.
This is an experimental study which explores the physical, mechanical, and economic factors involved in the production of type CEM II A-B/W cement. In this context, 4 cement additives were used in two different dosages (200 and 800 g/t). Class C fly ash was used for composite cement production at ratios of 5%, 20%, and 35%. It was shown that Blaine fineness increases with the increasing fly ash content. The use of fly ash at ratios of 5% and 20% was not found to have any unfavorable effects on the compressive strength at the early days. It is found that the use of additive for improving the early-age strength is preferable when fly ash is used. It is possible to produce Class 52.5 N cement using additives to improve early strength and 20% fly ash. Loss in strength was observed in cement mortars produced using glycol-based grinding aid. Increasing the dosage of chemical additive also led to loss in strength due to nonhomogeneous distribution of hydration products. As a result, grinding fly ash with clinker and the use of cement chemicals contribute to the cement sector in terms of sustainability. It is possible to produce cements with improved mechanical properties especially with the use of 20% fly ash.