| 1. |
- Gong, Fang, et al.
(författare)
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An overview on spalling behavior, mechanism, residual strength and microstructure of fiber reinforced concrete under high temperatures
- 2023
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Ingår i: Frontiers in Materials. - : Frontiers Media S.A.. - 2296-8016. ; 10
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Forskningsöversikt (refereegranskat)abstract
- Recent research has shown that the incorporation of fibres, such as steel and polypropylene fibres, in concrete can significantly improve its resistance to spalling under high-temperature conditions. However, the reported outcomes of studies on the spalling performance of Fibre Reinforced Concrete (FRC) vary significantly due to differences in cementitious matrix and fibre types, mix design, and testing techniques. Existing review studies have struggled to systematically and precisely consolidate the diverse aspects of the literature. To address these limitations, this paper adopts the latest approach for mining, processing, and analyzing data to interpret bibliographic data on the fire resistance of FRC. The primary objective of this study is to comprehensively explore the viability of FRC as a fire-resistant and refractory material. In pursuit of this goal, the paper thoroughly reviews various aspects of FRC behavior at elevated temperatures, including pore pressure behaviors. Moreover, this review also discusses spalling behaviors, mechanisms, and residual mechanical properties under high temperatures. The microstructural analysis of FRC is also discussed comprehensively to gain an in-depth understanding of its behavior under elevated temperatures. By analyzing available data, this study aims to shed light on the potential of FRC as a suitable material for resisting spalling in high-temperature scenarios. Additionally, the research delves into prospects and challenges in achieving sustainable FRC with enhanced spalling resistance, considering both material and structural levels.
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| 2. |
- Iftikhar, Bawar, et al.
(författare)
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A machine learning-based genetic programming approach for the sustainable production of plastic sand paver blocks
- 2023
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Ingår i: Journal of Materials Research and Technology. - : Elsevier Editora Ltda. - 2238-7854. ; 25, s. 5705-5719
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Tidskriftsartikel (refereegranskat)abstract
- Plastic sand paver blocks (PSPB) provide a sustainable alternative by reprocessing plastic waste and decreasing reliance on environmentally hazardous materials such as concrete. They promote waste management and environmentally favorable building practices. This paper presents a novel method for estimating the compressive strength (CS) of plastic sand paver blocks based on gene expression programming (GEP) techniques. The database collected from the experimental work comprises 135 compressive strength results. Seven input parameters were involved in predicting the CS of PSPB, namely, plastic, sand, sand size, fiber percentage, fibre length, fibre diameter, and tensile strength of the fibre. Simplified mathematical expressions were used to figure out the CS. The results of GEP formulations showed that they were better in line with the experimental data, with R2 values for CS of 0.89 (training) and 0.88 (testing). The models' performance was evaluated using sensitivity analysis and statistical checks. The statistical evaluations show that the actual and predicted values are closer together, which lends credence to the GEP model's capacity to forecast PSPB CS. The sensitivity analysis showed that sand size and fibre percentage contribute more than 50% of the CS in PSPB. In addition, the results demonstrate that the proposed models are accurate and have a robust capacity for generalization and prediction. This research can improve environmental protection and economic benefit by enhancing the reuse of PSPB in producing green ecosystems.
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| 3. |
- Iftikhar, Bawar, et al.
(författare)
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Experimental study on the eco-friendly plastic-sand paver blocks by utilising plastic waste and basalt fibers
- 2023
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Ingår i: Heliyon. - : Elsevier. - 2405-8440. ; 9:6
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Tidskriftsartikel (refereegranskat)abstract
- Plastic waste poses a significant hazard to the environment as a result of its high production rates, which endanger both the environment and its inhabitants. Similarly, another concern is the production of cement, which accounts for roughly 8% of global CO2 emissions. Thus, recycling plastic waste as a replacement for cementitious materials may be a more effective strategy for waste minimisation and cement elimination. Therefore, in this study, plastic waste (low-density polyethylene) is utilised in the production of plastic sand paver blocks without the use of cement. In addition to this, basalt fibers which is a green industrial material is also added in the production of eco-friendly plastic sand paver blocks to satisfy the standard of ASTM C902-15 of 20 N/mm2 for the light traffic. In order to make the paver blocks, the LDPE waste plastic was melted outside in the open air and then combined with sand. Variations were made to the ratio of LDPE to sand, the proportion of basalt fibers, and sand particle size. Paver blocks were evaluated for their compressive strength, water absorption, and at different temperatures. Including 0.5% percent basalt fiber of length 4 mm gives us the best result by enhancing compressive strength by 20.5% and decreasing water absorption by 50.5%. The best results were obtained with a ratio of 30:70 LDPE to sand, while the finest sand provides the greatest compressive strength. Moreover, the temperature effect was also studied from 0 to 60 °C, and the basalt fibers incorporated in plastic paver blocks showed only a 20% decrease in compressive strength at 60 °C. This research has produced eco-friendly paver blocks by removing cement and replacing it with plastic waste, which will benefit the environment, save money, reduce carbon dioxide emissions, and be suitable for low-traffic areas, all of which contribute to sustainable development.
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| 4. |
- Khan, Yasar, et al.
(författare)
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Bio-inspired based meta-heuristic approach for predicting the strength of fiber-reinforced based strain hardening cementitious composites
- 2023
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Ingår i: Heliyon. - : Elsevier. - 2405-8440. ; 9:11
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Tidskriftsartikel (refereegranskat)abstract
- A recently introduced bendable concrete having hundred times greater strain capacity provides promising results in repair of engineering structures, known as strain hardening cementitious composites (SHHCs). The current research creates new empirical prediction models to assess the mechanical properties of strain-hardening cementitious composites (SHCCs) i.e., compressive strength (CS), first crack tensile stress (TS), and first crack flexural stress (FS), using gene expression programming (GEP). Wide-ranging records were considered with twelve variables i.e., cement percentage by weight (C%), fine aggregate percentage by weight (Fagg%), fly-ash percentage by weight (FA%), Water-to-binder ratio (W/B), super-plasticizer percentage by weight (SP%), fiber amount percentage by weight (Fib%), length to diameter ratio (L/D), fiber tensile strength (FTS), fiber elastic modulus (FEM), environment temperature (ET), and curing time (CT). The performance of the models was deduced using correlation coefficient (R) and slope of regression line. The established models were also assessed using relative root mean square error (RRMSE), Mean absolute error (MAE), Root squared error (RSE), root mean square error (RMSE), objective function (OBF), performance index (PI) and Nash-Sutcliffe efficiency (NSE). The resulting mathematical GP-based equations are easy to understand and are consistent disclosing the originality of GEP model with R in the testing phase equals to 0.8623, 0.9269, and 0.8645 for CS, TS and FS respectively. The PI and OBF are both less than 0.2 and are in line with the literature, showing that the models are free from overfitting. Consequently, all proposed models have high generalization with less error measures. The sensitivity analysis showed that C%, Fagg%, and ET are the most significant variables for all three models developed with sensitiveness index higher than 10 %. The result of the research can assist researchers, practitioners, and designers to assess SHCC and will lead to sustainable, faster, and safer construction from environment-friendly waste management point of view.
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| 5. |
- Qureshi, Hisham Jahangir, et al.
(författare)
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Prediction of compressive strength of two-stage (preplaced aggregate) concrete using gene expression programming and random forest
- 2023
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Ingår i: Case Studies in Construction Materials. - : Elsevier Ltd. - 2214-5095. ; 19
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this research is to predict preplaced-aggregate concrete (PAC) compressive strength (CS) by using machine learning approaches such as gene expression programming (GEP) and random forest (RF). PAC requires injecting a portland cement-sand grout with admixtures into a mold after coarse aggregate has been deposited, making CS prediction complicated and requiring substantial study. Machine learning methods were used to cut down on the time and money needed for extensive experimental testing. The database includes 135 values for CS with eleven input variables. There is an acceptable degree of agreement between predicted and experimental values, as shown by the CS R2 values of 0.94 for GEP and 0.96 for RF. When comparing RF with GEP, RF performed better as measured by R2. The lower values displayed by the statistical error also showed that RF performed better than GEP. To compare, the GEP model's COV, MAE, RSME, and RMSLE were 0.527, 1.569, 2.706, and 0.133, whereas those for RF were 0.450, 1.648, 2.17, and 0.092. The SHAP analysis showed the effects of each input parameter, illuminating the positive effect of increasing the superplasticizer content on strength and the negative effect of raising the water-to-binder ratio. Using machine learning approaches to forecast the CS of PAC, this study has the potential to boost environmental protection and economic advantage.
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| 6. |
- Zhang, Yin, et al.
(författare)
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Towards modern sustainable construction materials: a bibliographic analysis of engineered geopolymer composites
- 2023
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Ingår i: Frontiers in Materials. - : Frontiers Media SA. - 2296-8016. ; 10
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Forskningsöversikt (refereegranskat)abstract
- Engineered cementitious composites (ECC) exhibits impressive tensile strength but has significant environmental drawbacks due to high cement consumption. Recently, engineered geopolymer composites (EGC) have gained attention as a potential ECC alternative. This comprehensive study reviews the latest EGC advancements, encompassing mix design, design theory, engineering properties, environmental benefits, and durability. It emphasizes how factors like activators, precursors, fibers, additives, and aggregates impact EGC properties, making it a cost-effective material for fire, chemical resistance, and dynamic loads. To address limitations in traditional literature reviews, innovative research methods, including scientometric analysis, were employed to provide a cohesive analysis. This review aims to facilitate knowledge dissemination and collaboration by summarizing EGC advances and highlighting remaining challenges in developing practical applications. It is revealed from the review that various manufacturing methods enhance geopolymers, especially in geopolymer concrete, where replacing 50% of ordinary Portland cement with fly ash boosts strength. Geopolymer concrete excels in pre-cast applications, offering durability and resistance to harsh conditions as an eco-friendly alternative to Portland cement. It suits highway pavement, walls, marine coatings, and tiles, reducing carbon emissions and promoting efficient waste management. EGCs find broad use in construction due to their strong, durable, and eco-friendly qualities, supporting sustainable infrastructure development.
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| 7. |
- Zhou, Yi, et al.
(författare)
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An overview of recent advancements in fibre-reinforced 3D printing concrete
- 2023
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Ingår i: Frontiers in Materials. - : Frontiers Media SA. - 2296-8016. ; 10
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Forskningsöversikt (refereegranskat)abstract
- 3D printing, also known as additive manufacturing, has recently gained significant attention and popularity as a transformative technology across various industries. One area where 3D printing is making remarkable strides is in the construction field, particularly with the emergence of 3D printing concrete (3DPC). While 3DPC holds immense promise, there are still challenges to overcome, such as incorporating reinforcement. This study reviews the potential of using fibre reinforcement to overcome the challenge of making ductile concrete for 3D printing that can withstand substantial tensile stresses. Effects of various types of fibre addition on widespread aspects of 3DPC are systematically reviewed. This review study considers various aspects of 3DPC: rheological characteristics, buildability, anisotropic mechanical behavior, and ductility. These characteristics of fibre-reinforced 3DPC are discussed in light of the published literature. This research’s graphical and statistical visualizations offer valuable insights for academic scholars. This review summarizes recent advancements in fibre-reinforced 3DPC while highlighting the persisting challenges in developing fibre-reinforced 3DPC with desired properties for real-world applications.
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