Browsing by Author "Bodur B."
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Scopus Characteristics of hemp fibre reinforced foam concretes with fly ash and Taguchi optimization(2021-08-02) Gencel O.; Yavuz Bayraktar O.; Kaplan G.; Benli A.; Martínez-Barrera G.; Brostow W.; Tek M.; Bodur B.This study presents investigation on microstructural, mechanical, durability and thermal characteristics of hemp fibers (HFs) reinforced foam concrete with fly ash (FA) and Taguchi optimization approach. Three series of foam concretes mixtures were produced with foam contents of 50, 75 and 100 kg/m3. There is a reference mixture without HFs and FA. Thus, mixtures contain FA as cement replacement at the concentrations of 0%, 10%, 20%, 30%, 40% and 50%. HFs with varying fiber length were introduced into mixes at concentrations of 0.75%, 1.5% and 3% by weight of cement. Slump test was done to see workability. Compression and flexural properties were determined at 7, 28 and 91 days. Durability was investigated by high temperature, freeze–thaw and sulphate exposures. Thermal conductivity, drying shrinkage, porosity, water absorption and dry unit weight properties of foam concretes were also investigated. Experimental results were analyzed using Taguchi optimization approach. Addition of HFs provides very large compressive and flexural strength enhancements. FA addition reduces the drying shrinkage and thermal conductivity while it increases the high temperature resistance of foam concretes.Scopus Effect of using wastewater from the ready-mixed concrete plant on the performance of one-part alkali-activated GBFS/FA composites: Fresh, mechanical and durability properties(2023-10-01) Bodur B.; Bayraktar O.Y.; Benli A.; Kaplan G.; Tobbala D.E.; Tayeh B.Water scarcity is the world's most pressing issue, as concrete batching facilities and concrete mixer trucks produce massive amounts of wash water every day. Recycling waste water from ready-mix concrete factories' concrete washing water is critical for conserving hundreds of millions of tons of water and preventing water and soil contamination. This study examined the impact of waste washing water on the microstructural, durability, fresh, and mechanical characteristics of one-part alkali-activated ground blast furnace slag (GBFS)/fly as (FA) composites (AAC) containing partial and complete replacement of tap water under ambient conditions. GBFS was used as the main binder in the production of AAC. FA was also used as a binder at 0%, 25%, and 50% instead of GBFS. Sodium metasilicate (MS) was used as a one-part activator at two dosages 7.5% and 15% of the total binder. The fresh properties (setting time and flowability), physical properties, compressive and flexural strength (3, 7, 28, 90, and 180 days) and durability (high-temperature resistance, freeze, and thaw resistance, drying shrinkage, sorptivity, HCl and MgSO4 resistances, NaCl effect and alkali-silica reaction) and microstructure analysis were investigated. The findings showed that the use of wastewater (WW) instead of tap water (TW) contributed positively or had no serious negative effect on the mechanical and durability properties of AAC. Compressive strength of 72.37 MPa and 81.67 MPa was gained with the inclusion of 50%WW at 7.5 and 15 %MS content respectively. The findings showed that WW improved the workability of fresh ACC containing FA, reduced dry shrinkage and sorptivity of ACC with 15%MS content, and refined the pores of hardened ACC. The results also supported that WW contributed to the decrease in expansion due to ASR and sulfate expansion. Using WW improved the high temperature and F-T resistance of ACC mixtures containing 15%MS content.Scopus Improving the eco-efficiency of fiber reinforced composite by ultra-low cement content/high FA-GBFS addition for structural applications: Minimization of cost, CO2 emissions and embodied energy(2023-10-01) Kaplan G.; Bayraktar O.Y.; Li Z.; Bodur B.; Yılmazoglu M.U.; Alcan B.A.Scopus Insulating and fire-resistant performance of slag and brick powder based one-part alkali-activated lightweight mortars(2022-01-01) Koksal F.; Bayraktar O.Y.; Bodur B.; Benli A.; Kaplan G.Waste brick powder (WBP) has enough pozzolanic characteristics to be employed as a supplemental cementing material in Portland cement-based concrete or as a precursor in the manufacture of alkali activated materials. This study was aimed to study the strength, thermal, microstructural and durability properties of ground blast furnace slag (GBFS) and WBP based one-part alkali-activated lightweight mortars (AAMs) produced with expanded vermiculite. One-part AAM mixtures were produced by using GBFS and WBP as binary precursors. Sodium metasilicate powder was used as the alkali activator. Two curing regimes namely heat curing at 75°C for 24 h and air curing at ambient conditions were adopted. GBFS was used as main binder and WBP was added at the rates of 0%, 10%, 25%, and 50% instead of GBFS. Four different mixtures were prepared by replacing GBFS at the rates of 0%, 10%, 25%, and 50% with WBP for each curing regime (totally eight mixtures). Expanded vermiculite powder were used as lightweight aggregates in all mixtures. The effects of WBP on AAM mixtures properties, including flowability, compressive strength, flexural strength, dry bulk density, thermal conductivity, porosity, and water absorption were studied. The effects of WBP and curing regime on drying shrinkage, sorptivity were also investigated. High temperature performance of the produced mixtures were determined. Results showed that air-cured WBP incorporated AAM mixtures exhibited better compressive strength, flexural strength, shrinkage, and sorptivity performance than the heat-cured WBP incorporated AAM mixtures. The air-cured AAM mixtures containing 25% WBP achieved the best results of 5.69 and 1.43 MPa for compressive strength and flexural strength at test age of 28 days. The heat-cured 50% WBP incorporated AAM mixture showed the best high temperature resistance and the lowest thermal conductivity.Scopus Performance assessment of fiber-reinforced coral aggregate-based lightweight foam concrete for sustainable marine construction(2024-10-25) Bayraktar O.Y.; Danish A.; Bodur B.; Kaplan G.; Aydın A.C.; Ozbakkaloglu T.Scopus Physico-mechanical, thermal insulation and resistance characteristics of diatomite and attapulgite based geopolymer foam concrete: Effect of different curing regimes(2023-04-10) Kaplan G.; Yavuz Bayraktar O.; Bayrak B.; Celebi O.; Bodur B.; Oz A.; Aydin A.C.This study investigated the physicomechanical, durability and microstructure characteristics of geopolymer foam concrete (GFC) with a unit weight of less than 1500 kg/m3 produced using attapulgite and diatomite. In the blends, as the main binder was used 10, 20 and 40% attapulgite instead of ground blast furnace slag (GBFS). In addition, 30, 40 and 50 kg/m3 foam were used in the blends. Three alternative curing methods were used on GFC: steam (80 °C), water (∼22 °C), and an oven (80 °C). Thermal curing regimens last 24 h at a temperature of 80 °C. The blends’ porosity ranges from 36.8 to 53.3%, while their levels of water absorption range from 32.5 to 49.4%. Unit weights of hardened GFC samples range from 475 to 1226 kg/m3. On the 28th day, after applying the steam curing to blends with a 30 kg/m3 foam dosage, the compressive strength is greater than 5 MPa. After 900 °C heat treatment (elevated temperature effect), a blend with a foam dosage of 30 kg/m3 and 40% attapulgite produced compressive strengths of greater than 4 MPa. The blends’ depths of water penetration range from 22.1 to 27.8 mm. The drying shrinkage of the blends was increased by adding more foam and attapulgite. GFC's thermal conductivity coefficient varies from 0.134 to 0.354 W/m.K. Increasing the attapulgite and foam decreased the thermal conductivity coefficient. Reaction products such as CASH and NASH gels were observed in SEM examinations. As a result, it has been determined that the most suitable results (In terms of physico-mechanical, thermal insulation and strength Properties) can be obtained if steam curing is applied in blends with 20% attapulgite and 30 kg/m3 foam dosage.Scopus The effect of steel fiber aspect-ratio and content on the fresh, flexural, and mechanical performance of concrete made with recycled fine aggregate(2023-03-03) Yavuz Bayraktar O.; Kaplan G.; Shi J.; Benli A.; Bodur B.; Turkoglu M.In order to solve the problem of low toughness and easy cracking of recycled aggregate concrete, steel fibers were incorporated to recycled fine aggregate concrete (RAC) to prepare a sustainable fiber-reinforced concrete. Steel fibers of various contents (20, 35, 50 and 65 kg/m3) and aspect ratios (l/d = 40 and 55) were incorporated to the RAC, and their fresh properties, mechanical properties and microstructure were investigated. The results show that the slump of RAC decreases with increasing fiber aspect ratio and content. Meanwhile, incorporating a small amount of steel fibers (l/d = 40, 20 kg/m3) improves the 28-d compressive strength of RAC, but with further increase in fiber aspect ratio and content, the compressive strength of RAC decreases. The incorporation of steel fibers greatly improves the splitting tensile strength and flexural strength of RAC, and the steel fibers with high aspect ratio have a higher gain in strength. The 28-d flexural strength of concrete with 65 kg/m3 steel fibers (l/d = 40) increases by 148.11 % relative to plain RAC, while the 65 kg/m3 steel fibers with an aspect ratio of 55 makes RAC with increases by 243.78 %. The mass loss of fiber-reinforced RAC under abrasion is also lower than that of plain RAC, and the steel fiber with high aspect ratio performs better. For the load–deflection response, the incorporation of fibers increases the peak load, and also increases the flexural toughness and post-cracking toughness, with the greatest gain for high aspect ratio fibers.Scopus Usage of recycled fine aggregates obtained from concretes with low w/c ratio in the production of masonry plaster and mortar(2022-02-01) Kaplan G.; Turkoglu M.; Bodur B.; Bayraktar O.Y.In this study, fresh and hardened aspects of mortars being produced from RFAs (recycled fine aggregates) obtained from concretes, w/c (water/cement) ratio of which varies in the range of 0.47–0.55 have been examined. On the mortars experiments such as those relating with workability, mechanical properties, drying shrinkage, sorptivity, and apparent porosity have been conducted. As flow diameters of mortars are kept at the value of 16 ± 2 cm, as a/c (aggregate/cement) ratio increased, w/c ratios of mortars also increased. As paste volume of mortars decreased, their mechanical properties got diminished. Increase in a/c ratio has impacted flexural strength negatively. In a mortar with a/c ratio of 5 and RFA ratio of %75, compressive strength of nearly 12 MPa has been obtained. As a/c ratio and compressive and flexural strengths of mortars increased, drying shrinkage values got reduced. Drying shrinkage value of mortars having a/c ratio of 7 and RFA ratio of %100 on 56th day has fallen below 1000 µm. By means of high grains below 75 µm within body of RFA, water penetration depth values of mortars have reduced. However, in mortars being produced by using RFA, attention should be paid to a/c ratio with regard to capillarity. Due to older cement paste situated on RFA surface, as RFA content increases, apparent porosity values of mortars have increased. As a conclusion, it has been determined that RFA will be used in production of mortar and plaster and it will be recycled and hence, sustainable building material could be obtained.