Browsing by Author "Gencel O."

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Basalt fiber reinforced foam concrete with marble waste and calcium aluminate cement
(2023-02-01) Bayraktar O.Y.; Yarar G.; Benli A.; Kaplan G.; Gencel O.; Sutcu M.; Kozłowski M.; Kadela M.
As a typical cellular lightweight material, foam concrete is produced by mixing cement, water, aggregate and a suitable foaming agent and has a density usually below 1600 kg/m3. The large number of air spaces present in foam concrete ensures that the concrete has advantages such as lightweight, high fluidity during pouring, excellent thermal and sound insulation, superior fire resistance, and outstanding energy absorption capacity. Its high porosity and the connectivity of the pores, which can allow the entry of negative substances into the concrete environment, cause foam concrete to have a very low physico-mechanical and durability performance. To eliminate or reduce these disadvantages, this study adopted the use of basalt fibers (BF) as eco-friendly fiber type and calcium aluminate cement (CAC) as aluminous cement with waste marble powder (WMP) as aggregates in foam concrete. In that respect, 9 mixes with varying content of foaming agent (FC) and basalt fiber have been prepared. Assessment of mechanical performance was based on compressive and flexural strength after 6 h, 1, 7, and 28 days. Dry bulk density, thermal conductivity, porosity, water absorption, and sorptivity of the concretes were determined. Durability characteristics of the concretes were examined by dry shrinkage, high temperature, magnesium sulfate, sulfuric, and hydrochloric acids. The obtained results showed that the content of BF affected the compressive strength of the mixtures slightly negatively or positively depending on the FC. The lowest value in thermal conductivity was gained as 0.645 (W/m K) for the mixture incorporating 1% BF and 50 kg/m3 foam quantity. In addition, the foam concrete incorporating foam of 30 kg/m3 and 1% BF showed the best resistance against MgSO4. The mixture with 2% BF and 30 kg/m3 FC exhibited the lowest mass loss after HCI exposure.
Basalt fiber-reinforced foam concrete containing silica fume: An experimental study
(2022-04-04) Gencel O.; Nodehi M.; Yavuz Bayraktar O.; Kaplan G.; Benli A.; Gholampour A.; Ozbakkaloglu T.
Foam concrete refers to a type of low-density concrete that is commonly known to have favorable insulation and thermal performance due to its intentionally increased porosity. However, foam concrete is known to generally have a very low physico-mechanical and durability performance mainly due to its high porosity and the connectivity of the pores that can allow the entrance of unfavorable substances into the concrete medium. As a result, most often, foam concrete is considered inapplicable to major load bearing structural elements. To counter this tendency, this study adopted the use of basalt fibers with silica fume to increase the structural integrity of foam concrete. In that respect, 18 mixes with varying content of foaming agent, basalt fiber and silica fume have been prepared. Apparent porosity, water absorption, compressive, flexural and splitting tensile strength, sorptivity, ultrasonic pulse velocity (UPV), drying shrinkage, freeze–thaw, thermal conductivity, and thermal resistance tests were performed to evaluate the physico-mechanical, durability, and insulation properties of the produced foam concretes. Based on the results, a highly durable foam concrete with a maximum compressive, flexural and splitting tensile strength of ∼ 46, 6.9 and 3.07 MPa, respectively, has been developed. Furthermore, it is observed that the inclusion of silica fume can significantly influence the pore network and enhance fiber-paste matrix. The effect of basalt fiber, however, is found to be more dependent on the use of silica fume, potentially due to its low integration with cementitious paste. The results of this study are significant and point out to the great potential for producing a highly durable and lightweight insulating foam concrete through the use of basalt fiber and silica fume.
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.
Characteristics, energy saving and carbon emission reduction potential of gypsum wallboard containing phase change material
(2022-11-25) Yaras A.; Ustaoglu A.; Gencel O.; Sarı A.; Hekimoğlu G.; Sutcu M.; Erdogmus E.; Kaplan G.; Bayraktar O.Y.
Phase change materials (PCM) used in the development of building materials with thermal energy storage (TES) capacity can minimize temperature fluctuations by reducing the heating and cooling load in building envelopes due to their energy storage/release properties. The present study aims to produce, characterize and measure energy performance under real weather conditions of novel gypsum wallboard containing shape-stable attapulgite (ATP) based composite PCM as TES material. Shape-stable composite PCM was prepared by impregnating 1-Dodecanol (DD) into attapulgite (ATG) and then incorporated with gypsum in volume fraction of 25 and 50 %. The impacts of the shape stable ATG/DD composite PCM additive on the thermo-physical and mechanical properties were systematically assessed. The DCS measurements revealed that the shape-stable ATG/DD composite melts at 20.06 °C with a melting enthalpy of 115.9 J/g while the gypsum/shape-sable ATG/DD (50 v/v%) melts at 20.03 °C with melting enthalpy of 20.06 J/g. Thermoregulation tests demonstrated that the indoor temperatures of the test room made by gypsum/shape-stable composite PCM were about 1.2 °C–2.66 °C warmer than that of the reference gypsum room for about 6–12 h in a cold weather. Theoretical calculations showed that the thermal enhanced gypsum wallboard, because of its TES capability, has a favorable future in terms of energy savings and low CO2 emission.
Development, characterization, and performance analysis of shape-stabilized phase change material included-geopolymer for passive thermal management of buildings
(2022-12-01) Gencel O.; Harja M.; Sarı A.; Hekimoğlu G.; Ustaoğlu A.; Sutcu M.; Erdogmus E.; Kaplan G.; Bayraktar O.Y.
The cooperation between phase change materials (PCMs) and geopolymer (GP) is energy-efficient way for improving the thermal performance of construction materials. This study discusses the effect of PCM combination with GP matrix on obtained concretes' mechanical and thermal properties. Attapulgite/lauric-capric acid eutectic mixture (ATP/LCEM) composite was fabricated as shape-stable composite phase change material (SSPCM) and then integrated with GP concrete (GPC) for improvement of the thermal mass of buildings. Thermal, mechanical, physical, morphological, thermal energy storage (TES) characteristics, and solar thermoregulation performances of the developed GPC-SSPCMs were experimentally characterized. The compressive strength was found over 6 MPa for GPC without aggregates (only SSPCM). The compressive and flexural strengths were relatively low, but above the requirements of the current standards. Other properties as thermal conductivity and solar performance make the produced GPC-SSPCMs promising materials for advanced TES applications in buildings. The apparent porosity was around 45% for GPC-SSPCM-50 and 63% for GPC-SSPCM-100, while water adsorption around 21% for GPC-SSPCM-50 and 30% for GPC-SSPCM-100. Thermal conductivity values of 0.375 W/mK for GPC without aggregates recommended this material as an insulator. The produced SSPCM composite melts at 19.00°C with corresponding latent heat of 73.9 J/g, while the GPC-SSPCM melts at 18.30°C with corresponding latent heat of 6.57 J/g. Based on the obtained outcomes, the energy-saving was determined as 5.56 kWh, which is corresponding to the CO2 saving of 15 kg-CO2, 14.68 kg-CO2, and 2.41 kg-CO2 in case of using coal, natural gas, or electricity, respectively as energy source.
Effect of cement dosage and waste tire rubber on the mechanical, transport and abrasion characteristics of foam concretes subjected to H2SO4 and freeze–thaw
(2021-10-04) Bayraktar O.Y.; Soylemez H.; Kaplan G.; Benli A.; Gencel O.; Turkoglu M.
This paper presents an experimental study of the effects of cement dosage and waste tire rubber as aggregate on the mechanical, transport and abrasion characteristics of foam concretes subjected to H2SO4 and freeze–thaw cycles. Foam concrete mixtures were made with two percentages 0, and 20 of silica fume (SF) as partial substitution of Portland cement (PC) and with 100% of waste tire rubber (WRA) as substitution of fine aggregates. Two groups of mixtures were prepared with SF contents of 0% and 20%. At each group of mixtures, three cement contents of 300, 400 and 500 kg/m3 and three foam contents of 20, 40 and 60 kg/m3 were used to produce concretes mixtures having water/binder (w/b) ratio of 0.75. Workability of fresh concretes were assessed by performing slump test. Compressive and flexural strength of the mixtures were determined after 7 and 28 days and transport properties were measured by means of porosity and water absorption after 28 days. Tests for shrinkage, sorptivity, abrasion, acid attack and freeze–thaw cycles of 30 and 60 were also performed in addition to microstructure investigations. An optimization was also performed. The results exhibited that increase in cement dosage resulted in the compressive strength by 204.50% maximum increment at cement content of 500 kg/m3 as compared to the mixture with dosage of 300 kg/m3 at foam content of 20 kg/m3. Based on the results, it was concluded that the lowest and highest shrinkage values of 5032 × 10−6 and 7065 × 10-6 mm/mm were gained for the mixtures with cement dosages of 300 kg/m3 and 500 kg/m3 and foam content of 20 kg/m3 respectively. The results also indicated that SF blended mixture with cement content of 500 kg/m3 foam content of 20 kg/m3 showed the best resistance after abrasion, F-T cycles and acid attack exposure.
Effect of waste marble powder and rice husk ash on the microstructural, physico-mechanical and transport properties of foam concretes exposed to high temperatures and freeze–thaw cycles
(2021-07-12) Gencel O.; Benli A.; Bayraktar O.Y.; Kaplan G.; Sutcu M.; Elabade W.A.T.
An experimental program was performed to evaluate the impact of rice husk ash (RHA) as cement replacement and waste marble powder (WMP) as sand replacement on the microstructural, mechanical and transport properties of foamed concrete exposed to high temperature and freeze–thaw cycles. For this, Portland Cement (PC) was replaced by RHA at 10% and 20%wt of binder and silica sand was replaced by WMP at 25% and 50%wt of fine aggregates to cast foamed concrete mixtures. Two different foam contents of 40 kg/m3 and 80 kg/m3 were used in the production of foamed concretes with water/binder (w/b) ratio of 0.70. Two reference mixtures were produced from silica sand and without RHA at each foam content. Other foam concretes were fabricated from 25% and 50% WMP instead of silica sand and 10% and 20% RHA instead of cement. Fresh properties of mixtures were evaluated by performing slump test. Transport properties of foam concretes were investigated, including porosity, sorptivity and water absorption after 90 days curing. Mechanical properties of foam concretes were investigated, including compressive and flexural strength ultrasonic pulse velocity (UPV) after 7, 28 and 90 days. Drying shrinkage and thermal conductivity of concretes were also studied after 90 days. Durability of concretes were also investigated after exposure to the temperature of 200, 400, 600 and 800 °C and freeze–thaw (F-T) cycles of 100 and 200 in addition to microstructure investigations. Results show that 10% RHA as cement substitute and 50% WMP as sand substitute give optimum percentage especially at late-age of 90 days at foam content of 40 kg/m3. The lowest drying shrinkage and sorptivity were obtained by using 10%RHA and 25%WMP. The results also indicate that water cooled specimens showed more strength loss than air cooled specimens after 200 °C. The worst F-T performance was obtained for the mixture containing 10% RHA and without WMP by 43.8 and 59.8% strength reductions.
Foam Concrete Produced with Recycled Concrete Powder and Phase Change Materials
(2022-06-01) Gencel O.; Nodehi M.; Hekimoğlu G.; Ustaoğlu A.; Sarı A.; Kaplan G.; Bayraktar O.Y.; Sutcu M.; Ozbakkaloglu T.
In construction industry, phase change materials (PCMs), have recently been studied and found effective in increasing energy efficiency of buildings through their high capacity to store thermal energy. In this study, a combination of Capric (CA)-Palmitic acid (PA) with optimum mass ratio of 85–15% is used and impregnated with recycled concrete powder (RCP). The resulting composite is produced as foam concrete and tested for a series of physico-mechanical, thermal and microstructural properties. The results show that recycled concrete powder can host PCMs without leaking if used in proper quantity. Further, the differential scanning calorimetry (DSC) results show that the produced RCP/CA-PA composites have a latent heat capacity of 34.1 and 33.5 J/g in liquid and solid phases, respectively, which is found to remain stable even after 300 phase changing cycles. In this regard, the indoor temperature performance of the rooms supplied with composite foams made with PCMs, showed significantly enhanced efficiency. In addition, it is shown that inclusion of PCMs in foam concrete can significantly reduce porosity and pore connectivity, resulting in enhanced mechanical properties. The results are found promising and point to the suitability of using RCP-impregnated PCMs in foam composites to enhance thermo-regulative performance of buildings. On this basis, the use of PCMs for enhanced thermal properties of buildings are recommended, especially to be used in conjunction with foam concrete.
Influence of bottom ash and polypropylene fibers on the physico-mechanical, durability and thermal performance of foam concrete: An experimental investigation
(2021-11-01) Gencel O.; Kazmi S.M.S.; Munir M.J.; Kaplan G.; Bayraktar O.Y.; Yarar D.O.; Karimipour A.; Ahmad M.R.
Recently, foam concrete (FC) has been widely considered due to higher workability, lightweight, lower cost, thermal and fire resistance relatively to conventional concrete. This study intends to measure the properties of FC incorporating bottom ash (BA) as fine aggregates (FA) and polypropylene fibers (PPF). A total of 18 concrete mixes were produced with two cement contents: 300 and 400 kg/m3. In addition, three foam agent contents (40, 50, and 60 kg/m3) and three PPF contents (0, 0.5, and 1% in terms of volume) were used and considered to investigate the physical, mechanical, thermal, and durability properties of PPF-reinforced FC incorporating BA. Furthermore, the effect of elevated temperature on the properties of specimens was also examined. Results show an increase in apparent porosity, water absorption, and sorptivity of FC with the increase in foam agent content. Conversely, a reduction in thermal conductivity, porosity, and shrinkage is observed with an increase in foam agent, cement, and PPF contents, respectively. The rise in foam agent content declines the mass loss while improves both compressive and flexural strengths of FC under an elevated temperature. Scanning electron microscopic (SEM) analysis of the FC specimens after exposure to the elevated temperature shows the cracks and inter-connected pores due to the thermal stresses by decomposing calcium silicate phases. Results show that all the FC mixes incorporating BA as FA and PPF can be used as moderate-strength concrete following American Concrete Institute guidelines, leading to enhanced FC performance and sustainable construction.
Investigation of neutron shielding properties depending on number of boron atoms for colemanite, ulexite and tincal ores by experiments and FLUKA Monte Carlo simulations
(2012-01-01) Korkut T.; Karabulut A.; Budak G.; Aygün B.; Gencel O.; Hançerlioĝullari A.
241 Am-Be source and three samples including different amounts of boron atoms per unit volume called colemanite, ulexite and tincal were used in total macroscopic cross section experiments. Also FLUKA Monte Carlo code was used to simulate total macroscopic cross sections, absorbed doses and deposited energies by low energy neutron interactions. Besides half value layers of samples were calculated and compared to paraffin. As a result, ascending concentration of boron atoms can enhance neutron shielding property of samples. © 2011 Elsevier Ltd.
Investigation of physico-mechanical, thermal properties and solar thermoregulation performance of shape-stable attapulgite based composite phase change material in foam concrete
(2022-04-01) Gencel O.; Ustaoglu A.; Benli A.; Hekimoğlu G.; Sarı A.; Erdogmus E.; Sutcu M.; Kaplan G.; Yavuz Bayraktar O.
Thermal energy storage (TES) by means of phase change materials (PCM) is of great concern to decrease heating and cooling loads. In building envelopes, one of the most efficient TES methods is integration of PCMs with construction materials for preventing temperature fluctuations by taking advantage of energy storage/release feature of PCMs. Aim of this research was to develop novel foam concretes containing shape-stable attapulgite (ATP) based composite PCM as TES material. Shape-stable ATP/Capric-Myristic acid eutectic mix composite (ATP/C-M) was incorporated into foam concrete at three different ratios (15, 30 and 45 wt%) and characterized. Impacts of ATP/C-M inclusion on physico-mechanic and TES characteristics of foam concretes including composite PCM (FCPCM) were worked systematically. DSC results showed that ATP/C-M composite melts at 22.12 °C with latent heat storage capacity of 74.97 J/g, whereas FCPCM-45 melts at 21.05 °C with latent heat storage ability of 10.98 J/g. Inclusion of ATP/C-M instead of silica sand decreased flow diameter of foam concretes. Compared to reference mixture FCPCM-0, compressive strengths of FCPCM-15, FCPCM-30 and FCPCM-45 samples were reduced in the range of 11–46% while reduction in flexural strength was found to be about 35–57% at 28th day. All FCPCM samples showed lower thermal conductivity values than the specified value and could be defined as better insulation materials. Solar thermoregulation performances of foam concretes containing ATP/C-M were comparatively tested in laboratory and also actual ambient conditions. Results showed that foam concretes with acceptable mechanical properties can be used for internal temperature controlling and energy saving in buildings.
Lightweight foam concrete containing expanded perlite and glass sand: Physico-mechanical, durability, and insulation properties
(2022-02-21) Gencel O.; Yavuz Bayraktar O.; Kaplan G.; Arslan O.; Nodehi M.; Benli A.; Gholampour A.; Ozbakkaloglu T.
Foam concrete refers to a type of concrete with high porosity that can be produced with or without aggregate. Foam concrete has generally superior thermal insulation properties compared to conventional concrete. Despite its major thermal benefits, the high content of Portland cement, as well as its very high porosity, makes foam concrete prone to physico-durability concerns such as drying shrinkage by allowing the entrance of chemicals and free water to the concrete pores. To address this and reduce the pore network connectivity, in this study, expanded perlite and fine-sized waste glass sand were used as the main aggregates in concrete mixes. In that respect, 10 mixes of foam concrete were produced with two foam contents of 50 and 100 kg/m3, with a constant water-to-binder ratio (w/b) of 0.5. In each mix, the dominated expanded perlite aggregate was replaced by waste glass sand having a size of < 2.36 mm. Apparent porosity, water absorption, compressive and flexural strength, sorptivity, ultrasonic pulse velocity (UPV), drying shrinkage, freeze–thaw, alkali-silica reaction, thermal conductivity, and thermal resistance tests were performed to investigate the physico-mechanical, durability and insulation properties of the foam concrete. Based on the results, it is found that the addition of glass sand improves physico-mechanical and durability properties of foam concrete. The addition of expanded perlite increases the insulating properties of foam concrete, potentially due to the high porosity of expanded perlite compared to that of glass sand. The findings of this study point to the suitability of producing sustainable insulating foam concrete through the use of waste glass sand.
Mechanical and durability properties of steel fiber-reinforced concrete containing coarse recycled concrete aggregate
(2021-10-01) Kaplan G.; Bayraktar O.Y.; Gholampour A.; Gencel O.; Koksal F.; Ozbakkaloglu T.
The focus of this study is to investigate the effect of using coarse recycled concrete aggregates (RCAs) as an alternative material to natural coarse aggregate on the fresh, mechanical and durability behavior of concrete reinforced with steel fiber. Eighteen unique concrete mixes with RCA content of 0%, 50%, and 100% and steel fiber content of 0%, 1%, and 2% were prepared, and tests were performed to study slump, density, compressive and splitting tensile strengths, flexural behavior, surface hardness, surface abrasion resistance, water absorption, and sorptivity of each mix. It is shown that concrete containing RCA has a lower unit weight, compressive, splitting tensile and flexural strength, flexural toughness, surface hardness, and abrasion resistance, and a higher water absorption and sorptivity in comparison with conventional concrete. An increased compressive, splitting tensile and flexural strength, flexural toughness, surface hardness, and abrasion resistance, and a decreased water absorption and sorptivity of concrete with an increased steel fiber content from 1% to 2% is less significant compared to those from 0% to 1%. The results also show that, at RCA content of 50%, incorporating 1% steel fiber develops a concrete mix with similar or even better properties compared to unreinforced conventional concrete. At 100% RCA content, incorporating 2% steel fiber develops a concrete mix with similar properties to unreinforced conventional concrete having water to cement ratio of 0.3, but inferior properties to unreinforced conventional concrete having water to cement ratio of 0.5. These findings indicate that recycled aggregate concrete with similar or even better properties compared to concrete with natural aggregate can be developed through properly designing mixes, providing a great avenue toward the production of green construction material for structural applications.
Optimization of foam concrete characteristics using response surface methodology and artificial neural networks
(2022-06-27) Kursuncu B.; Gencel O.; Bayraktar O.Y.; Shi J.; Nematzadeh M.; Kaplan G.
In this study, influences of waste marble powder (WMP) and rice husk ash (RHA) partially replaced instead of fine aggregate and cement into foam concrete (FC) on compressive and flexural strength, porosity, and thermal conductivity coefficient were investigated using Response Surface Methodology (RSM) and Artificial Neural Networks (ANN) methods. The foam parameter was determined as two levels in the experimental design, and the WMP and RHA parameters were determined as three levels. With the RSM analysis, the most influential parameters for compressive and flexural strength were determined as Foam WMP and RHA, respectively. Likewise, the order of effective parameters for porosity and thermal conductivity coefficient was found as foam WMP and RHA. With the RSM method, R2 values were obtained as 0.9492 for compressive strength, 0.9312 for flexural strength, 0.9609 for porosity, and 0.9778 for thermal conductivity coefficient. Correlation coefficients with the ANN method were found as 0.98393, 0.96748, 0.9933, and 0.96946 for compressive and flexural strength, porosity, and thermal conductivity coefficient, respectively. The ANN method was found to be suitable for estimating the responses. The RSM method was found to be suitable both for estimating the responses and for determining the effective parameters. In addition, the optimum parameters were determined by the RSM method.
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.
Physico-mechanical, durability and thermal properties of basalt fiber reinforced foamed concrete containing waste marble powder and slag
(2021-06-21) Yavuz Bayraktar O.; Kaplan G.; Gencel O.; Benli A.; Sutcu M.
Recently, the usage of industrial wastes for concrete production has played an important role for developing environmentally friendly building materials. This work focused on investigating physico-mechanical, durability and thermal properties of basalt fibers (BF) reinforced foamed concrete containing waste marble powder (WMP) and ground granulated blast furnace slag (GGBFS). Foamed concretes were fabricated with 50 kg/m3 and 100 kg/m3 contents of a protein-based foaming agent at 0.75 water/binder (w/b) ratio. Two control mixtures in which silica sand used as fine aggregates and containing no BF were developed at each foam content. Other foamed mixtures were produced with WMP as fine aggregates and GGBFS as white Portland cement (WPC) replacement at the rates of 0%, 30% and 60%. BF were also added to the mixtures at the rates of 0%, 1% and 2% by weight of cement. Fresh properties of mixtures investigated were slump and fresh unit weight. Experiments were also fulfilled to evaluate 7, 28, 90 and 180-day water-cured mechanical strengths. Porosity, water absorption and sorptivity were studied after 28 aged cured specimens. Dry unit weight, thermal conductivity and drying shrinkage properties of foamed concrete specimens were assessed on 28 aged specimens. High temperature and freeze–thaw durability of foamed concrete specimens were also examined. Results indicated that very high compressive and flexural strength enhancements of 179.49%, 141.79% and 139.91%, 93.18%, at 7 and 28 days were obtained using WMP and BF addition respectively. Coupling use of 30% GGBFS and 1%BF revealed the highest compressive strength of 32.57 MPa and lowest porosity value of 14.8% at foam content of 50 kg/m3.
Properties of eco-friendly foam concrete containing PCM impregnated rice husk ash for thermal management of buildings
(2022-10-15) Gencel O.; Sarı A.; Kaplan G.; Ustaoglu A.; Hekimoğlu G.; Bayraktar O.Y.; Ozbakkaloglu T.
Thermal energy storage (TES) through the use of construction materials incorporating phase change materials (PCMs) can prevent temperature fluctuations and allow energy saving in buildings. With this background, aim of this work is to develop new kind eco-friendly foam concrete (FC) containing lauryl alcohol (LA)-impregnated rice husk ash (RHA) composite PCM. RHA, an agricultural waste product, was used as a carrier material to eliminate the leakage problem of LA. Thus, leakage-free composite PCM (LFCPCM) was first prepared, and then such an RHA-based LFCPCM was integrated with cementitious FC for the first time in this study. The fabricated novel FCs were subjected to detailed examinations in terms of morphological, mechanical, physical, and TES properties. The DSC outcomes indicated that LFCPCM showed melting phase change at 19.97 °C and had a latent heat TES capacity of 99.60 J/g, while the PCM into FC-LFCPCM50 melted at 20.01 °C and had a latent heat TES capacity of 16.55 J/g. Solar thermoregulation performance test results revealed that compared to the reference FC (RFC), the FC-LFCPCM50 wallboard provided about 1.29 °C warmer indoor temperature during the cold weather hours, whereas the room center temperature was about 2.8 °C lower during the daytime in hot weather conditions. An energy-saving of 14.28 kW h per day is obtained by FC-LFCPCM50 wallboard. The carbon emission equivalences of this energy-saving amount account for 38 kg-CO2, 37.7 kg-CO2, and 6.19 kg-CO2 for coal, natural gas, and electricity, respectively. These results suggest that the fabricated novel FC-LFCPCM50 can be effectively evaluated as green building materials for thermo-regulation and energy saving of buildings.
The effect of limestone and bottom ash sand with recycled fine aggregate in foam concrete
(2022-08-15) Gencel O.; Balci B.; Bayraktar O.Y.; Nodehi M.; Sarı A.; Kaplan G.; Hekimoğlu G.; Gholampour A.; Benli A.; Ozbakkaloglu T.
To follow resource conservation, the production of optimized and sustainable structures through the use of insulating materials, such as foam concrete, has become a trend in construction industry. Although foam concrete has numerous benefits, the larger use of Portland cement in its mixture and its relatively low thermo-durability properties because of the low quantity of solid materials are of major concerns, challenging its large-scale applications. In that respect, this research evaluates the use of recycled fine concrete aggregate, limestone and bottom ash sand as the main aggregate materials to evaluate the physico-mechanical and thermo-durability properties of foam concrete. To that end, 25 mixes have been produced and a comprehensive series of tests including flowability, compressive and flexural strengths, water absorption, apparent porosity, drying shrinkage, sorptivity, abrasion resistance, thermal conductivity, along with the effect of elevated temperature and its respective cooling regime on foam concretes have been conducted in this study. The results show that foam concretes manufactured with bottom ash and recycled fine aggregates develop a considerably lower thermal conductivity values despite being outperformed in physico-mechanical properties by those mixes produced with limestone sand. Nonetheless, the inclusion of bottom ash sand is found to produce foam concretes with a comparable physico-mechanical and thermo-durability properties to mixes with limestone. The results of this study point to the suitability of utilizing alternative fine-sized aggregates, such as recycled fine aggregates along with bottom ash sand, in the production of foam concrete without compromising the insulating properties of the produced concrete.
The use of waste marble for cleaner production of structural concrete: A comprehensive experimental study
(2022-12-26) Gencel O.; Nodehi M.; Yavuz Bayraktar O.; Kaplan G.; Benli A.; Koksal F.; Bilir T.; Siddique R.; Ozbakkaloglu T.
Waste marble is a byproduct that is produced as a result of cutting and reshaping marble stone that is commonly used in the construction sector. From a sustainability perspective, waste marble can be a potential alternative to limestone sand with slightly reduced ecological footprint which is aligned with novel concepts, such as circularity of construction industry. To provide a comprehensive outline of marble's use as coarse aggregate in concrete production, this study adopted utilizing waste coarse marble aggregate (WCMA) at a quantity of 50% and 100% to substitute coarse limestone aggregates (also natural coarse aggregate (NCA)). Likewise, since marble stone is considered as a metamorphic rock with slightly different microspores, compared to limestone, three different water-to-cement ratios (w/c) of 0.35, 0.42 and 0.49 have also been used. Results show that concretes incorporating WMCA exhibit a slightly better mechanical performance than concretes incorporating NCA, given that the w/c ratio is enough to lubricate WMCA's surface but not to the point of increasing free water in concrete's microstructure. In other words, it is found that WMCA is relatively sensitive to the mixture's w/c ratio which can have a large impact on the resulting physico-mechanical and thermo-durability properties of the specimens. In this regard, despite the WMCA's slightly enhanced performance in certain thermo-durability tests, the interfacial transition zone (ITZ) areas are found to be more susceptible to deteriorating factors. Nonetheless, the result of this study is found to be significant and point to the suitability of utilizing WMCA as an alternative to NCA.