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25 pages, 5454 KiB

Open AccessArticle

Multi-Objective Optimization of Sustainable Concrete Containing Fly Ash Based on Environmental and Mechanical Considerations

by Kennedy C. Onyelowe, Denise-Penelope N. Kontoni, Ahmed M. Ebid, Farshad Dabbaghi, Atefeh Soleymani, Hashem Jahangir and Moncef L. Nehdi

Buildings 2022, 12(7), 948; https://doi.org/10.3390/buildings12070948 - 4 Jul 2022

Cited by 48 | Viewed by 4336

Abstract

Infrastructure design, construction and development experts are making frantic efforts to overcome the overbearing effects of greenhouse gas emissions resulting from the continued dependence on the utilization of conventional cement as a construction material on our planet. The amount of CO₂ emitted [...] Read more.

Infrastructure design, construction and development experts are making frantic efforts to overcome the overbearing effects of greenhouse gas emissions resulting from the continued dependence on the utilization of conventional cement as a construction material on our planet. The amount of CO₂ emitted during cement production, transportation to construction sites, and handling during construction activities to produce concrete is alarming. The present research work is focused on proposing intelligent models for fly ash (FA)-based concrete comprising cement, fine and coarse aggregates (FAg and CAg), FA, and water as mix constituents based on environmental impact (P) considerations in an attempt to foster healthier and greener concrete production and aid the environment. FA as a construction material is discharged as a waste material from power plants in large amounts across the world. Its utilization as a supplementary cement ensures a sustainable waste management mechanism and is beneficial for the environment too; hence, this research work is a multi-objective exercise. Intelligent models are proposed for multiple concrete mixes utilizing FA as a replacement for cement to predict 28-day concrete compressive strength and life cycle assessment (LCA) for cement with FA. The data collected show that the concrete mixes with a higher amount of FA had a lesser impact on the environment, while the environmental impact was higher for those mixes with a higher amount of cement. The models which utilized the learning abilities of ANN (-BP, -GRG, and -GA), GP and EPR showed great speed and robustness with R² performance indices (SSE) of 0.986 (5.1), 0.983 (5.8), 0.974 (7.0), 0.78 (19.1), and 0.957 (10.1) for Fc, respectively, and 0.994 (2.2), 0.999 (0.8), 0.999 (1.0), 0.999 (0.8), and 1.00 (0.4) for P, respectively. Overall, this shows that ANN-BP outclassed the rest in performance in predicting Fc, while EPR outclassed the others in predicting P. Relative importance analyses conducted on the constituent materials showed that FA had relatively good importance in the concrete mixes. However, closed-form model equations are proposed to optimize the amount of FA and cement that will provide the needed strength levels without jeopardizing the health of the environment. Full article

(This article belongs to the Special Issue Sustainable and Green Construction Materials: Opportunities for New and Existing Structures)

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25 pages, 32777 KiB

Open AccessArticle

Dynamic Behavior of the Composite Steel–Concrete Beam Floor Systems under Free and Forced Vibration

by Faham Tahmasebinia, Cho Sum Yip, Chio Fai Lok, Yufan Sun, Junyi Wu, Samad M. E. Sepasgozar and Fernando Alonso Marroquin

Buildings 2022, 12(3), 320; https://doi.org/10.3390/buildings12030320 - 8 Mar 2022

Cited by 2 | Viewed by 3370

Abstract

This paper aims to investigate the dynamic behavior of composite steel–concrete floor systems under both free and forced vibrations. A combination of numerical and analytical methods was comprehensively employed to calibrate the suggested solutions to extend the application of accurate numerical methods in [...] Read more.

This paper aims to investigate the dynamic behavior of composite steel–concrete floor systems under both free and forced vibrations. A combination of numerical and analytical methods was comprehensively employed to calibrate the suggested solutions to extend the application of accurate numerical methods in future design purposes. Different commercial Finite Element Packages including ABAQUS/CAE and Strand7 were precisely utilized. The obtained results from the Finite Element Simulations were broadly compared with the available international design guidelines including British Standard BS 6472 and international standard ISO 10137. The first 10 active vibration modes in different composite steel–concrete beam floor systems were numerically investigated. Different concrete slabs by respecting the designated various types of secondary and primary steel beam components were comprehensively examined. It was found that the lengths of primary and secondary beams can considerably influence the computed fundamental frequencies and the response factors of the simulated composite floor system. Based on carrying out an extensive parametrical study, further practical recommendations were suggested to provide a reliable benchmark for structural designers. Full article

(This article belongs to the Special Issue Sustainable and Green Construction Materials: Opportunities for New and Existing Structures)

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18 pages, 5265 KiB

Open AccessArticle

Experimental Investigation of Unconfined Compressive Properties of Artificial Ice as a Green Building Material for Rinks

by Wenyuan Zhang, Junxing Li, Baojiang Yuan, Lin Wang and Qiyong Yang

Buildings 2021, 11(12), 586; https://doi.org/10.3390/buildings11120586 - 26 Nov 2021

Cited by 3 | Viewed by 2370

Abstract

The construction of a prefabricated ice rink has recently attracted considerable interest owing to its detachability, short building period, and high cooling efficiency, among other benefits. Characterizing the compressive properties of an artificial ice sheet is crucial in the design, operation, and maintenance [...] Read more.

The construction of a prefabricated ice rink has recently attracted considerable interest owing to its detachability, short building period, and high cooling efficiency, among other benefits. Characterizing the compressive properties of an artificial ice sheet is crucial in the design, operation, and maintenance stages of the rink. Several uniaxial compressive tests were conducted in the present work to better understand the mechanical behavior of artificial ice in winter sports rinks. The artificial ice was produced using homemade equipment to simulate the real ice-making conditions in the rink. Comprehensive conditions such as strain rate, ice temperature, ice-making method, water quality, air temperature and humidity were considered in the experiments. The obtained results show that the compressive behavior of artificial ice is considerably affected by the strain rate and ice temperature, and slightly affected by the ice-making method and water quality, whereas the effects of air temperature and humidity are inconclusive. The identified range of strain rate for ductile-brittle transition was within 8.3 × 10⁻⁵ s^–1 and 8.3 × 10⁻⁴ s⁻¹, in which the strength reaches a maximum value at 1.7 × 10^–4 s⁻¹. The influencing factors on the compressive strength and effective modulus were analyzed based on the experimental observations, and fitting functions were established to describe the relationships. The results of this study will hopefully provide a reference for the design and optimization of ice rinks, particularly for prefabricated rinks. Full article

(This article belongs to the Special Issue Sustainable and Green Construction Materials: Opportunities for New and Existing Structures)

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17 pages, 6244 KiB

Open AccessArticle

Volume Stability of Cement Paste Containing Limestone Fines

by Jamal Khatib, Rawan Ramadan, Hassan Ghanem and Adel Elkordi

Buildings 2021, 11(8), 366; https://doi.org/10.3390/buildings11080366 - 19 Aug 2021

Cited by 20 | Viewed by 3135

Abstract

The common cause of cracking in cement paste is shrinkage due to different reasons, such as loss of water and chemical reactions. Incorporating limestone fines (LF) as a cement replacement can affect the shrinkage of the paste. To examine this effect, five paste [...] Read more.

The common cause of cracking in cement paste is shrinkage due to different reasons, such as loss of water and chemical reactions. Incorporating limestone fines (LF) as a cement replacement can affect the shrinkage of the paste. To examine this effect, five paste mixes were prepared with 0, 5, 10, 15 and 20% LF as a cement replacement and with a water-to-binder ratio (w/b) of 0.45. Four volume stability tests were conducted for each paste: chemical, autogenous and drying shrinkage and expansion. Chemical shrinkage was tested each hour for the first 24 h and thereafter every 2 days for a total period of 90 days. The drying shrinkage, autogenous shrinkage and expansion were monitored every 2 days until 90 days. The results showed that replacing 15% LF enhanced the chemical shrinkage of the paste. However, autogenous shrinkage of the paste was found to increase between 0 and 10% LF and decline sharply at 15 and 20% LF. Drying shrinkage was found to increase with the increase in LF content. Expansion exhibited little variation between 0 and 10% LF and an increase for replacement above 15% LF. These results are discussed in terms of the formation of hydration products and self-desiccation due to hydration. Full article

(This article belongs to the Special Issue Sustainable and Green Construction Materials: Opportunities for New and Existing Structures)

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17 pages, 4952 KiB

Open AccessArticle

Applied Element Modelling of Warping Effects in Thin-Walled C-Shaped Steel Sections

by Giammaria Gabbianelli

Buildings 2021, 11(8), 328; https://doi.org/10.3390/buildings11080328 - 29 Jul 2021

Cited by 2 | Viewed by 2977

Abstract

The Applied Element Method (AEM) is a relatively recent numerical technique, originally conceived for simulating the large displacement nonlinear response of reinforced concrete, masonry and steel structures, and successful applications have been presented by various researchers. Recently, AEM was used to model the [...] Read more.

The Applied Element Method (AEM) is a relatively recent numerical technique, originally conceived for simulating the large displacement nonlinear response of reinforced concrete, masonry and steel structures, and successful applications have been presented by various researchers. Recently, AEM was used to model the mechanical behaviour of steel storage pallet racks, i.e., particular cold-formed steel structures typically employed for storing goods and materials. Such systems are often subjected to peculiar displacements and stresses due to warping effects, which are inherent and often govern their behaviour, increasing the peak strength and ultimate displacement demand. This phenomenon has not been studied through AEM yet; hence, this work investigates the capabilities of AEM in simulating the warping effects in typical steel rack members, i.e., thin-walled C-shaped sections. Preliminary results and comparison against established modelling approaches indicate that AEM can accurately simulate this phenomenon, both in terms of displacements and stresses. Full article

(This article belongs to the Special Issue Sustainable and Green Construction Materials: Opportunities for New and Existing Structures)

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16 pages, 4233 KiB

Open AccessArticle

Development of Sustainable and Eco-Friendly Materials from Termite Hill Soil Stabilized with Cement for Low-Cost Housing in Chad

by Assia Aboubakar Mahamat, Numfor Linda Bih, Olugbenga Ayeni, Peter Azikiwe Onwualu, Holmer Savastano, Jr. and Winston Oluwole Soboyejo

Buildings 2021, 11(3), 86; https://doi.org/10.3390/buildings11030086 - 26 Feb 2021

Cited by 16 | Viewed by 3521

Abstract

This paper explores the effects of cement stabilization (5, 10, 15 and 20 wt%) on the structural and mechanical properties (compressive/flexural strengths and fracture toughness) of abandoned termite mound soil. The crystal structures and crystallinity of the constituents were determined using X-ray diffraction [...] Read more.

This paper explores the effects of cement stabilization (5, 10, 15 and 20 wt%) on the structural and mechanical properties (compressive/flexural strengths and fracture toughness) of abandoned termite mound soil. The crystal structures and crystallinity of the constituents were determined using X-ray diffraction (XRD), while the microstructure was characterized via scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). The functional groups were also identified using Fourier transform infra-red spectroscopy (FTIR). The compressive/flexural strengths of the stabilized and un-stabilized termite mound soil were also studied after curing for 7, 14 and 28 days. The fracture toughness mechanism was analyzed with the aid of the R-curve method. Additionally, the underlying deformation and cracking mechanisms are elucidated via in-situ/ex-situ optical and scanning electron microscopy. The stabilized termite mound soil displayed the highest mechanical properties of 13.91 MPa, 10.25 MPa and 3.52 kPa·m^1/2 for compressive strength, flexural strength and fracture toughness, respectively. Besides displaying good mechanical properties and being locally available at no cost, renewable and an eco-friendly material, the termite mound soil will contribute to lowering the cost of housing in Sub-Saharan Africa, particularly in Chad. Full article

(This article belongs to the Special Issue Sustainable and Green Construction Materials: Opportunities for New and Existing Structures)

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22 pages, 13166 KiB

Open AccessArticle

Experimental and Numerical Study of Behaviour of Reinforced Masonry Walls with NSM CFRP Strips Subjected to Combined Loads

by Houria Hernoune, Benchaa Benabed, Antonios Kanellopoulos, Alaa Hussein Al-Zuhairi and Abdelhamid Guettala

Buildings 2020, 10(6), 103; https://doi.org/10.3390/buildings10060103 - 31 May 2020

Cited by 10 | Viewed by 6287

Abstract

Near surface mounted (NSM) carbon fibers reinforced polymer (CFRP) reinforcement is one of the techniques for reinforcing masonry structures and is considered to provide significant advantages. This paper is composed of two parts. The first part presents the experimental study of brick masonry [...] Read more.

Near surface mounted (NSM) carbon fibers reinforced polymer (CFRP) reinforcement is one of the techniques for reinforcing masonry structures and is considered to provide significant advantages. This paper is composed of two parts. The first part presents the experimental study of brick masonry walls reinforced with NSM CFRP strips under combined shear-compression loads. Masonry walls have been tested under vertical compression, with different bed joint orientations 90° and 45° relative to the loading direction. Different reinforcement orientations were used including vertical, horizontal, and a combination of both sides of the wall. The second part of this paper comprises a numerical analysis of unreinforced brick masonry (URM) walls using the detailed micro-modelling approach (DMM) by means of ABAQUS software. In this analysis, the non-linearity behavior of brick and mortar was simulated using the concrete damaged plasticity (CDP) constitutive laws. The results proved that the application of the NSM-CFRP strips on the masonry wall influences significantly strength, ductility, and post-peak behavior, as well as changing the failure modes. The adopted DMM model provides a good interface to predict the post peak behavior and failure mode of unreinforced brick masonry walls. Full article

(This article belongs to the Special Issue Sustainable and Green Construction Materials: Opportunities for New and Existing Structures)

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Review

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27 pages, 6667 KiB

Open AccessReview

Geopolymers as Sustainable Material for Strengthening and Restoring Unreinforced Masonry Structures: A Review

by Anabel B. Abulencia, Ma. Beatrice D. Villoria, Roneh Glenn D. Libre, Jr., Pauline Rose J. Quiatchon, Ithan Jessemar R. Dollente, Ernesto J. Guades, Michael Angelo B. Promentilla, Lessandro Estelito O. Garciano and Jason Maximino C. Ongpeng

Buildings 2021, 11(11), 532; https://doi.org/10.3390/buildings11110532 - 11 Nov 2021

Cited by 9 | Viewed by 4152

Abstract

Unreinforced masonry (URM) structures are vulnerable to earthquakes; thus, materials and techniques for their strengthening and restoration should be developed. However, the materials used in some of the existing retrofitting technologies for URM and the waste produced at its end-of-life are unsustainable. The [...] Read more.

Unreinforced masonry (URM) structures are vulnerable to earthquakes; thus, materials and techniques for their strengthening and restoration should be developed. However, the materials used in some of the existing retrofitting technologies for URM and the waste produced at its end-of-life are unsustainable. The production of ordinary Portland cement (OPC) worldwide has enormously contributed to the global carbon footprint, resulting in persistent environmental problems. Replacing OPC with geopolymers, which are more sustainable and environmentally friendly, presents a potential solution to these problems. Geopolymers can replace the OPC component in engineering cementitious composites (ECC), recommended to strengthen and restore URM structures. In the present paper, the state-of-the-art knowledge development on applying geopolymers in URM structures is discussed. The discussion is focused on geopolymers and their components, material characterization, geopolymers as a strengthening and restoration material, and fiber-reinforced geopolymers and their application to URM structures. Based on this review, it was found that the mechanical properties of geopolymers are on par with that of OPC; however, there are few studies on the mentioned applications of geopolymers. The characterization of geopolymers’ mechanical and physical properties as a restoration material for URM structures is still limited. Therefore, other properties such as chemical interaction with the substrate, workability, thixotropic behavior, and aesthetic features of geopolymers need to be investigated for its wide application. The application method of geopolymer-based ECC as a strengthening material for a URM structure is by grouting injection. It is also worth recommending that other application techniques such as deep repointing, jacketing, and cement-plastering be explored. Full article

(This article belongs to the Special Issue Sustainable and Green Construction Materials: Opportunities for New and Existing Structures)

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