Citation: Joyklad, P.; Yooprasertchai, E.; Rahim, A.; Ali, N.; Chaiyasarn, K.; Hussain, Q. Sustainable and Low-Cost Hemp FRP Composite Confinement of B-Waste Concrete. Sustainability 2022, 14, 7673. https://doi.org/10.3390/su14137673 Academic Editors: Libo Yan, Ruoyu Jin, Yidong Xu and Zhenhua Duan Received: 12 May 2022 Accepted: 20 June 2022 Published: 23 June 2022 Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affil- iations. Copyright: © 2022 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/). sustainability Article Sustainable and Low-Cost Hemp FRP Composite Confinement of B-Waste Concrete Panuwat Joyklad 1 , Ekkachai Yooprasertchai 2, * , Abdur Rahim 3 , Nazam Ali 4 , Krisada Chaiyasarn 5 and Qudeer Hussain 6 1 Department of Civil and Environmental Engineering, Faculty of Engineering, Srinakharinwirot University, Nakhonnayok 26120, Thailand; panuwatj@g.swu.ac.th 2 Construction Innovations and Future Infrastructure Research Center (CIFIR), Department of Civil Engineering, Faculty of Engineering, King Mongkut’s University of Technology Thonburi, Bangkok 10140, Thailand 3 Department of Transportation Engineering and Management, University of Engineering and Technology, Lahore 54890, Pakistan; rahim@uet.edu.pk 4 Department of Civil Engineering, University of Management and Technology, Lahore 54770, Pakistan; nazam.ali@umt.edu.pk 5 Thammasat Research Unit in Infrastructure Inspection and Monitoring, Repair and Strengthening (IIMRS), Thammasat School of Engineering, Faculty of Engineering, Thammasat University Rangsit, Pathum Thani 12000, Thailand; ckrisada@engr.tu.ac.th 6 Center of Excellence in Earthquake Engineering and Vibration, Department of Civil Engineering, Chulalongkorn University, Bangkok 10330, Thailand; ebbadat@hotmail.com * Correspondence: ekkachai.yoo@kmutt.ac.th Abstract: Each year, massive amount of construction waste is generated that needs proper attention in terms of its disposal without deteriorating surrounding environment. A significant portion of this waste comprises bricks. Besides, large number of new construction works are resulting in the depletion of natural resources rapidly. Intuitively, a sustainable solution demands to consume this construction waste in the best way possible. This study targeted brick waste as a potential material to be used as a partial replacement of natural aggregates in structural concrete. It has been known that the concrete constructed with recycled brick aggregates possesses substandard mechanical properties. Traditionally, synthetic FRPs are known tostrengthen recycled aggregate concrete. However, recognizing high costs associated with them, this study proposed the use of natural hemp fiber ropes to strengthen recycled aggregate concrete constructed with brick aggregates. To assess the efficacy of hemp ropes in strengthening mechanical properties of the concrete with coarse aggregates partially replaced with recycled brick aggregates (B-waste), an experimental framework was conducted. Sixteen cylindrical specimens were tested in two groups depending upon the concrete strength. Within each group, 2 specimens each were strengthened with 1, 2, and 3 layers of hemp fiber ropes. Axial monotonic compressive loading was applied to each specimen. Results revealed that hemp fiber ropes significantly improved ultimate compressive strength and the corresponding strain. A substantial improvement in axial ductility was observed. For the sake of performance-based non-linear modelling, accurate constitutive modelling at material level is necessary. For this purpose, several existing analytical stress-strain models were tested in this study to predict ultimate confined compressive strength and strain. It was found that several models predicted confined compressive strengths with reasonable accuracy. However, very few models were able to predict confined peak strain with good accuracy. Keywords: hemp fiber rope; recycled aggregate concrete; cement-clay interlocking brick aggregates; stress-strain models 1. Introduction Concrete has been utilized in construction works for decades ascribing to its easy preparation, availability, and durability. It has been reported that concrete is the second Sustainability 2022, 14, 7673. https://doi.org/10.3390/su14137673 https://www.mdpi.com/journal/sustainability