| 1. |
- Ahmed Waqas, Hafiz, et al.
(författare)
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Performance Prediction of Hybrid Bamboo-Reinforced Concrete Beams Using Gene Expression Programming for Sustainable Construction
- 2023
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Ingår i: Materials. - : MDPI. - 1996-1944. ; 16:20
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Tidskriftsartikel (refereegranskat)abstract
- The building and construction industry’s demand for steel reinforcement bars has increased with the rapid growth and development in the world. However, steel production contributes to harmful waste and emissions that cause environmental pollution and climate change-related problems. In light of sustainable construction practices, bamboo, a readily accessible and ecofriendly building material, is suggested as a viable replacement for steel rebars. Its cost-effectiveness, environmental sustainability, and considerable tensile strength make it a promising option. In this research, hybrid beams underwent analysis through the use of thoroughly validated finite element models (FEMs), wherein the replacement of steel rebars with bamboo was explored as an alternative reinforcement material. The standard-size beams were subjected to three-point loading using FEMs to study parameters such as the load–deflection response, energy absorption, maximum capacity, and failure patterns. Then, gene expression programming was integrated to aid in developing a more straightforward equation for predicting the flexural strength of bamboo-reinforced concrete beams. The results of this study support the conclusion that the replacement of a portion of flexural steel with bamboo in reinforced concrete beams does not have a detrimental impact on the overall load-bearing capacity and energy absorption of the structure. Furthermore, it may offer a cost-effective and feasible alternative.
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| 2. |
- Bansal, Manisha, et al.
(författare)
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Influence of pozzolanic addition on strength and microstructure of metakaolin-based concrete
- 2024
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Ingår i: PLOS ONE. - : PLoS. - 1932-6203. ; 19:4
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Tidskriftsartikel (refereegranskat)abstract
- The intent of this study is to explore the physical properties and long-term performance of concrete made with metakaolin (MK) as a binder, using microsilica (MS) and nanosilica (NS) as substitutes for a portion of the ordinary Portland cement (OPC) content. The dosage of MS was varied from 5% to 15% for OPC-MK-MS blends, and the dosage of NS was varied from 0.5% to 1.5% for OPC-MK-NS blends. Incorporation of these pozzolans accelerated the hardening process and reduced the flowability, consistency, and setting time of the cement paste. In addition, it produced a denser matrix, improving the strength of the concrete matrix, as confirmed by scanning electron microscopy and X-ray diffraction analysis. The use of MS enhanced the strength by 10.37%, and the utilization of NS increased the strength by 11.48% at 28 days. It also reduced the penetrability of the matrix with a maximum reduction in the water absorption (35.82%) and improved the resistance to the sulfate attack for specimens containing 1% NS in the presence of 10% MK. Based on these results, NS in the presence of MK can be used to obtain cementitious structures with the enhanced strength and durability.
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| 3. |
- Çelik, Ali İhsan, et al.
(författare)
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Mechanical performance of geopolymer concrete with micro silica fume and waste steel lathe scraps
- 2023
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Ingår i: Case Studies in Construction Materials. - : Elsevier. - 2214-5095. ; 19
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Tidskriftsartikel (refereegranskat)abstract
- Environmental studies for solutions are among the most important agendas of the scientific world. Most of the new studies are taking into account environmental effects. However, it is interesting for the scientific world to find solutions for accumulated environmental problems, to reduce harmful production, and to turn wastes that cause environmental pollution into useful products. In addition to incorporating fly ash, a recognized environmentally friendly and sustainable material, geopolymer concrete, utilizes micro silica fume (micro silica) as a binding agent. Furthermore, waste lathe scraps are introduced to enhance and safeguard the concrete’s mechanical properties. During the preparation phase, significant enhancements have been identified in the workability and setting time of concrete. A total of 16 test samples were prepared in this study. Micro silica of 0%, 5%, 10%, and 20%, and lathe scraps of 0%, 1%, 2%, and 3% were examined. Experimental findings revealed that incorporating 5% micro silica resulted in notable improvements in the compressive, flexural, and splitting tensile strengths, with the increases of 14.4%, 7.45%, and 6.18%, respectively. However, higher additions of 10% and 20% were found to decrease these strengths. In contrast, the inclusion of 1% lathe scraps led to considerable increases in the compressive, flexural, and splitting tensile strengths by 11.4%, 6.35%, and 8.23%, respectively. However, the addition of 2% and 3% lathe scraps resulted in the reduced capacity. The findings demonstrated that combining 5% micro silica with 1% lathe scraps provided the highest strength, with the improvements of 25.7%, 14.4%, and 12% in the compressive, flexural,and splitting tensile strengths, respectively. Considering the enhancements in the workability, setting time, and strengths observed in all the tests, the recommended optimal geopolymer mixture is 5% micro silica together with 1% lathe scraps.
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| 4. |
- Çelik, Ali İhsan, et al.
(författare)
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Use of waste glass powder toward more sustainable geopolymer concrete
- 2023
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Ingår i: Journal of Materials Research and Technology. - : Elsevier. - 2238-7854 .- 2214-0697. ; 24, s. 8533-8546
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Tidskriftsartikel (refereegranskat)abstract
- The influence of waste glass powder (WGP) with fly ash in certain proportions on geopolymer concrete (GPC) was investigated by exchanging different proportions of molarity and WGP percentages in GPC. For this objective, fly ash was altered with WGP having percentages of 10%, 20%, 30%, and 40%, and the effect of molarity of sodium hydroxide (NaOH) was examined. The compressive strength tests, splitting tensile tests, and flexural strength tests were conducted. The workability and setting time were also evaluated. With the addition of WGP, the workability for molarities (M) of 11, 13, and 16 NaOH reduced by an average of 17%, 10%, and 67%, respectively. The findings showed that the slump values decreased as the molarity and WGP percentages increased. Molarity significantly affected the setting time, but WGP had no effect on the setting time. Although high molarity increased the capacity, this had a noticeable negative effect on the setting time and workability. This study demonstrated that WGP had a slight negative effect on the capacity and workability. Furthermore, when the combined effects of WGP and NaOH molarity were taken into account, the use of 10% WGP with M13 NaOH was recommended to obtain the optimum sustainable GPC considering both fresh and hardening properties. Scanning electron microscopy (SEM) analysis was done on the samples, too.
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| 5. |
- Dulaimi, Anmar, et al.
(författare)
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Innovative geopolymer-based cold asphalt emulsion mixture as eco-friendly material
- 2023
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Ingår i: Scientific Reports. - : Springer. - 2045-2322. ; 13
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Tidskriftsartikel (refereegranskat)abstract
- In recent years, there has been a growing interest in cold asphalt emulsion mixture (CAEM) due to its numerous advantages, including reduced CO2 emissions, energy savings, and improved safety during construction and application. However, CAEM has often been considered inferior to hot mix asphalt (HMA) in terms of performance. To address this issue and achieve desirable performance characteristics, researchers have been exploring the modification of CAEM using high-cost additives like ordinary Portland cement. In this study, the focus was on investigating the effects of utilizing waste alkaline Ca(OH)2 solution, ground granulated blast-furnace slag (GGBFS), and calcium carbide residue (CCR) as modifiers to enhance the properties of CAEM. The aim was to develop an innovative geopolymer geopolymer-based cold asphalt emulsion mixture (GCAE). The results of the study revealed that the use of waste alkaline Ca(OH)2 solution led to an increase in early hydration, which was confirmed through scanning electron microscopy. Furthermore, the experimental findings demonstrated that waste alkaline Ca(OH)2 solution significantly contributed to the rapid development of early-age strength in GCAE. As a result, GCAE showed great potential for utilization in pavement applications, particularly for roads subjected to harsh service conditions involving moisture and temperature. By exploring these alternative modifiers, the study highlights a promising avenue for enhancing the performance of CAEM and potentially reducing the reliance on expensive additives like ordinary Portland cement. The development of GCAE has the potential to offer improved performance and durability in pavement applications, thus contributing to sustainable and efficient road infrastructure.
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| 6. |
- Fayed, Sabry, et al.
(författare)
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Experimental study on using recycled polyethylene terephthalate and steel fibers for improving behavior of RC columns
- 2023
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Ingår i: Case Studies in Construction Materials. - : Elsevier. - 2214-5095. ; 19
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Tidskriftsartikel (refereegranskat)abstract
- In this research, the behavior of RC columns reinforced with recycled polyethylene terephthalate (PET) fibers and steel fibers (SFs) was experimentally investigated. The experimental work included testing of 8 columns with the dimensions of 150 × 150 × 1000 mm subjected to the axial loading up to failure. Three volume fractions (1%, 2%, and 3%) were considered for both PET fibers and SFs. The axial/lateral displacements of the columns and the transverse/vertical strains versus the loads of the bars were recorded. The peak load, yield load, failure mode, ductility, and stiffness of the columns were studied in detail. The effects of plastic fibers (PFs) and SFs on the concrete characteristics were experimentally examined. Using 2% SFs in the mix increased the compressive strength, tensile strength, and toughness of concrete by 12.7%, 87.6%, and 304.8%, respectively. Furthermore, enhancement rates of the ultimate load capacity, stiffness, and ductility of the columns with 2% SFs were 15.6%, 72.6%, and 34.29%, respectively. The ultimate load capacity, initial stiffness, and ductility of the columns reinforced with 1% PF fiber were 9.43%, 62.6%, and 19.4%, respectively, greater than those of the columns without fibers. The columns’ capacity was decreased with increasing SFs and PFs over 2%. An equation from ACI was used to predict the columns’ capacity and the results agreed well with the experimental results.
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| 7. |
- Jwaida, Zahraa, et al.
(författare)
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The Use of Waste Polymers in Asphalt Mixtures: Bibliometric Analysis and Systematic Review
- 2023
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Ingår i: Journal of Composites Science. - : MDPI. - 2504-477X. ; 7:10
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Tidskriftsartikel (refereegranskat)abstract
- Asphalt is widely employed in road construction due to its durability and ability to withstand heavy traffic. However, the disposal of waste polymers has emerged as a significant environmental concern. Recently, researchers have used polymer waste to modify asphalt pavements as a new approach. This approach aims to improve pavement performance and address the environmental concerns of polymer waste. Researchers have demonstrated that incorporating polymeric waste into asphalt mixtures can lead to performance improvements in asphalt pavements, particularly in mitigating common distresses including permanent deformation and thermal and fatigue cracking. The current comprehensive review aims to summarize the recent knowledge on the usage of waste polymers in asphalt mixtures, encompassing their impact on performance properties and mixture design. The review also addresses different types of waste polymers, their potential benefits, challenges, and future research directions. By analyzing various studies, this review offers insights into the feasibility, effectiveness, and limitations of incorporating waste polymers into asphalt mixtures. Ultimately, this contributes to the advancement of sustainable and environmentally friendly road construction practices.
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| 8. |
- Madenci, Emrah, et al.
(författare)
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Behavior of functionally graded carbon nanotube reinforced composite sandwich beams with pultruded GFRP core under bending effect
- 2024
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Ingår i: Frontiers in Materials. - : Frontiers. - 2296-8016. ; 10
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Tidskriftsartikel (refereegranskat)abstract
- A novel generation of composite sandwich beams with laminated carbon fiber-reinforced polymer skins and pultruded glass fiber-reinforced polymer core materials was examined for their flexural behavior. The strength and failure mechanisms of the composite sandwich beams in flatwise and edgewise configurations were investigated using three-point static bending tests. These sophisticated composite structures must be designed and used in a variety of sectors, and our research provides vital insights into their performance and failure patterns. In comparison to the reference specimens (FGM-1), the carbon nanotube-reinforced specimens’ bending capacity was affected and ranged from −2.5% to 7.75%. The amount of the carbon nanotube addition had a substantial impact on the beams’ application level and load-carrying capacity. Particularly, the application of 0.5 wt% additive in the outermost fiber region of the beams, such as in FGM-4, led to an increase in the bending capacity. However, the stiffness values at the maximum load were decreased by 0.3%–18.6% compared to FGM-1, with the minimum level of the decrease in FGM-4. The experimental results were compared with the theoretical calculations based on the high-order shear deformation theory, which yielded an approximation between 11.99% and 12.98% by applying the Navier’s solution.
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| 9. |
- Madenci, Emrah, et al.
(författare)
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Experimental investigation and analytical verification of buckling of functionally graded carbon nanotube-reinforced sandwich beams
- 2024
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Ingår i: Heliyon. - : Elsevier. - 2405-8440. ; 10:8
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Tidskriftsartikel (refereegranskat)abstract
- Carbon nanotube (CNT) reinforcement can lead to a new way to enhance the properties of composites by transforming the reinforcement phases into nanoscale fillers. In this study, the buckling response of functionally graded CNT-reinforced composite (FG-CNTRC) sandwich beams was investigated experimentally and analytically. The top and bottom plates of the sandwich beams were composed of carbon fiber laminated composite layers and hard core. The hard core was made of a pultruded glass fiber-reinforced polymer (GFRP) profile. The layers of FG-CNTRC surfaces were reinforced with different proportions of CNT. The reference sample was made of only a pultruded GFRP profile. In the study, the reference sample and four samples with CNT were tested under compression. The largest buckling load difference between the reference sample and the sample with CNT was 37.7%. The difference between the analytical calculation results and experimental results was obtained with an approximation of 0.49%–4.92%. Finally, the buckling, debonding, interlaminar cracks, and fiber breakage were observed in the samples.
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| 10. |
- Majeed, Samadar S., et al.
(författare)
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Development of ultra-lightweight foamed concrete modified with silicon dioxide (SiO2) nanoparticles: Appraisal of transport, mechanical, thermal, and microstructural properties
- 2024
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Ingår i: Journal of Materials Research and Technology. - : Elsevier. - 2238-7854 .- 2214-0697. ; 30, s. 3308-3327
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Tidskriftsartikel (refereegranskat)abstract
- Over the last few decades, researchers have devoted significant consideration to the use of nanoscale elements in concrete. Silicon dioxide nanoparticles (SDNs) have been a popular subject of study among the several types of nanoparticles. This article describes the findings of a laboratory investigation that examined the properties of ultra-lightweight foamed concrete (ULFC) including different proportions of SDNs. Wide range of the properties was evaluated specifically the slump flow, density, consistency, flexural strength, modulus of elasticity, compressive strength, split tensile strength, thermal properties, porosity, water absorption, sorptivity, intrinsic air permeability, and chloride diffusion. Additionally, the scanning electron microscopy (SEM) and pore distributions analyses of different mixes were done. Results confirmed a noticeable increase in the mechanical properties of ULFC, with respective improvements in the 28-day compressive, split tensile, and flexural strengths of up to 70.49%, 76.19%, and 51.51%, respectively, at 1.5% of the SDNs inclusion. However, further increases in the SDNs percentage did not result in remarkable enhancements. As the SDN percentage increased from 1.5% to 2.5%, the ULFC’s sorptivity, porosity, water absorption, intrinsic air permeability, and chloride diffusion showed substantial improvements. When compared to the control sample, ULFC with SDNs demonstrated higher thermal conductivity values. The reason for this occurrence was determined to be the smaller pore size observed in the ULFC specimens containing SDNs. A great adjustment in the distribution of pore diameters was witnessed in the ULFC mixes when the percentages of SDNs were adjusted. The ULFC specimens, which included SDNs at the percentages of 0.5%, 1.0%, and 1.5%, indicated a reduction in the total number of large voids measuring 500 nm or more, compared to the control ULFC specimen. The findings of this study highlight the potential benefits of incorporating SDNs into ULFC, which may improve its overall properties.
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