This paper investigates the bond between high-strength concrete (HSC) and tensile lap-spliced basalt fiber-reinforced polymer (BFRP) bars. Ten large-scale BFRP-reinforced concrete beams (300 × 450 × 3900 mm) were fabricated and tested under four-point loading until failure. The parameters investigated included the BFRP bar diameter (10, 12, and 16 mm), the splice length (400–1200 mm range), and the bar surface texture (sand-coated (SC) and helically wrapped (HW)). Test results demonstrated that the flexural capacity of the beams reinforced with SC-BFRP bars was almost similar to that of beams reinforced with HW-BFRP bars. However, SC-BFRP bars showed a slightly higher bond with concrete compared to that of helically wrapped counterparts. The bond strength of spliced BFRP bars was inversely related to the splice length. Also, BFRP bars with larger diameter bars require longer splice lengths to reach their maximum capacity. Finally, the experimentally estimated critical splice lengths were compared to those calculated by existing models and code-based equations. Both ACI 440.1R-15 and CSA S806-12 provisions were conservative in predicting splice length for BFRP bars. However, the CSA-S6-14 design code was more accurate in estimating the splice length for BFRP with bigger diameters. Though, it was not conservative with smaller diameters.

An important step towards achieving sustainability goals in the construction sector is taken by developing solutions that adopt ‘greener’ structural materials for buildings. This paper establishes a comparison among four existing residential buildings in Sweden, that utilize different structural solutions, in terms of their global warming potential (GWP). The structural solutions compared are prefabricated reinforced concrete (RC), light timber frame, cross-laminated timber (CLT) panels, and CLT modular construction. For each building, a life cycle assessment (LCA) was performed to estimate the greenhouse gas (GHG) emissions attributable to material production. In general, the results of this study revealed climate benefits associated with timber-based construction, with approximately 50% savings on average in the GHG emissions per unit floor area of the buildings as compared to prefabricated RC construction. Finally, this effort demonstrates the significance of the structural material choice on the overall carbon footprint of a building, especially at the production stage. © 2022 ISEC Press.

The building industry is a large contributor to greenhouse gas (GHG) emissions and a vast consumer of natural resources. It is estimated that, in the next 40 years, around 415 Gt of CO₂ will be released as a result of global construction activities. Therefore, improvements in construction technologies are essential to reduce GHG emissions and thereby attain national and international goals to mitigate climate change. Cross-laminated timber (CLT) has emerged as an innovative alternative material to steel/concrete in building construction, given its relatively low carbon footprint, not to mention its high strength-to-weight ratio, simple installation, and aesthetic features. CLT is a structural composite panel product developed in the early 1990s, and the contemporary generation of CLT buildings are yet to reach the end of their service life. Accordingly, there has been growing interest to understand and optimize the performance of CLT in building construction. In view of that, this paper presents an overview on the feasibility of using CLT in buildings from a life-cycle assessment (LCA) standpoint. The authors performed a brief review on LCA studies conducted in the past decade pertaining to the carbon footprint of CLT buildings. On average, the findings of these studies revealed about 40% reduction in carbon footprint when using CLT in lieu of conventional construction materials (steel/concrete) for multi-story buildings. Furthermore, the paper explores the challenges associated with conducting LCA on CLT buildings, identifies the gaps in knowledge, and outlines directions for future research.

The combined use of recycled concrete aggregate (RCA) and glass fiber reinforced polymer (GFRP) reinforcement in reinforced concrete (RC) structures is deemed plausible to achieve sustainable construction. This paper aims to examine the effect of such a combination (RCA + GFRP reinforcement) on the shear behavior of RC beams. Six medium-scale RC beams (150 × 260 × 2200 mm) critical in shear were tested under three-point loading until failure. The test variables were the aggregate type (natural/recycled) and the shear reinforcement (steel/GFRP/none). The failure modes, cracking patterns, load-carrying capacities, deformational and strain characteristics were analyzed and compared among the tested specimens. It was found that using 100% RCA in the concrete mix reduced the shear strength of RC beams (by 12% on average). Minor effects were observed on the shear strength of the beam specimens (∼2%) with altering the transverse reinforcement (GFRP versus steel). Theoretical load-carrying capacities of the tested beams were obtained as per contemporary design guides and compared with the experimental results.

The combined use of seawater and recycled tire aggregate (RTA) in concrete is potentially a way forward towards sustainable construction. It can help control harvesting of natural aggregates, manage waste tires, mitigate freshwater consumption and desalinationimpacts. The current paper aims at investigating the material performance and cost effectiveness of concrete mixed with seawater and RTA. The paper consists of two parts. The first part studies the characteristics (fresh and hardened) of concrete mixed with seawater and RTA. Thirteen concrete mixtures, varying in mixing water (seawater/freshwater) as well as fine and coarse aggregates (at 0%, 5%, 10%, and 20% replacement levels), were investigated. An extensive experimental program was conducted to compare the thirteen mixtures in terms of physical properties, workability, strength, water absorption, and chloride permeability. The second part of the paper performs a life cycle cost analysis (LCCA) for a 20-story building over a 100-year analysis period to verify the cost effectiveness of a proposed sustainable concrete that combines seawater, RTA (at 5% replacement level), and glass fiber-reinforced polymer (GFRP) reinforcement. A sensitivity analysis was performed to investigate the effect of the discount rate on the LCCA results.

Internationally, an annual number of more than a million fatalities are caused by road traffic crashes, with particularly signalized intersections being crash prone locations within the highway system. An accumulation of conflicts between drivers is caused by the different movements (through and turning) from different directions at the intersection; hence, studying the trajectories of turning vehicles is an important step towards improving traffic safety performance of these facilities. In view of that, the current paper aims at providing further insight into the behaviour of left-turning vehicles (right-hand traffic rule) at signalized intersections in the State of Qatar. At first, a total of 44 trajectories of free-flowing vehicles were manually extracted from a recorded video for a single approach of Lekhwair signalized intersection in Doha City, State of Qatar. After that, the extracted trajectories were statistically analysed in an attempt to explore the factors affecting the path of left-turning vehicles at signalized intersections. The results suggest that the characteristics of the extracted paths are significantly related to the vehicle’s entry speed, minimum speed throughout its turning manoeuvre, and the lateral distance between the exit point and the curb (i.e., targeted exit lane). Provided that the speed parameters can be fairly an indication to the driving behaviour, it can be concluded that the driver’s attitude plays an important role in drawing the manoeuvre of a turning vehicle as does the pre-selection of the exit lane. Finally, the effort presented in this paper can be regarded as a way forward towards understanding the behaviour of turning vehicles at signalised intersection in the State of Qatar.

Reinforced concrete tanks in water/wastewater treatment plants are susceptible to severe corrosion due to aggressive exposure conditions resulting from the application of certain treatment chemicals and methods. Non-corrosive materials, such as stainless steel or fiber reinforced polymer (FRP), may be attractive alternative reinforcement options for such concrete structures. However, the high initial cost of such materials imposes constraints on their use, although such thinking ignores improvements in long-term concrete durability. The current paper addresses the use of non-corrosive reinforcement in a concrete water chlorination tank using life-cycle cost analysis (LCCA) that aims to evaluate the cost effectiveness of different reinforcement alternatives. A comparison was established between four concrete reinforcing materials, namely, black steel, epoxy coated steel, stainless steel, and glass-FRP (GFRP) through a 100-year analysis period.

The results of this study suggest that the use of non-corrosive reinforcement helps achieve a considerable long-term cost saving. LCCA showed that GFRP becomes more economical than black steel in 35 years following construction. The net present cost (NPC) obtained for the GFRP-reinforced concrete was approximately 43% lower than that of the black steel reinforced concrete. The use of stainless steel also had a potential advantage but was less cost-effective than GFRP, with a 50-year payback period and an NPC 25% lower than that of the conventional design. Epoxy coated steel also showed a long-term cost benefit when compared to black steel, with approximately 11% reduction in NPC and 15-year extension in the service life. Sensitivity analyses were performed to assess the effects of the analysis period, discount rate, construction costs, concrete strength, and the use of supplementary cementitious materials on the LCCA outcomes.

Recently, textile reinforced mortar (TRM) has emerged as a viable strengthening material for reinforced concrete (RC) and masonry structures. Understanding the TRM tensile behaviour is important to achieve an accurate design for TRM strengthening systems. This paper investigates the tensile properties of carbon-TRM composite with multiple fabric plies. Twenty TRM specimens (410 × 50 mm), which varied in the number of fabric plies (one/two/three/four), were prepared and tested in accordance with AC 434 provisions (clevis-grip mechanism). The results revealed a significance of the number of fabric plies on the tensile capacity as well as the failure behaviour of the TRM composite. The failure mode had changed from ductile fabric slippage (associated with up to 3 fabric plies) to brittle fabric delamination in carbon-TRM specimens when using 4 layers of fabric. As expected, the TRM tensile capacity had proportionally increased with the number of fabric plies. The effect of the number of fabric plies was less significant (within 20%), though, on the ultimate tensile stresses of the impregnated fabric. The results verified the established bilinear trend for TRM tensile stress-strain relationship that indicates two sequential phases, namely, noncracked/stiff and cracked-section phases. However, the TRM cracked tensile modulus had somewhat increased with an increase in the number of fabric plies. © 2020, University of Cantabria - Building Technology R&D Group. All rights reserved.

Using seawater and/or recycled coarse aggregates (RCA) for concrete mixing is deemed advantageous from a sustainability perspective. This paper reports on the results of an experimental study on fresh and hardened properties of concrete mixed with seawater and RCA. Three concrete mixtures were investigated, namely, Mix A (traditional concrete), Mix B (concrete made with seawater), and Mix C (concrete made with seawater and RCA). It was concluded that the use of seawater and/or RCA had a notable effect on fresh concrete properties. Mix B concrete showed a slightly lower strength performance than that of Mix A (<15%), whereas the strength of Mix C concrete had a significant drop (~30%) compared to the reference (Mix A). The permeability performance of hardened concrete for Mixes A and B was similar, whereas Mix C concrete showed 60% increase in water absorption and 100% increase in chloride permeability as compared to Mix A.

This paper aims at developing a convolutional neural network (CNN)-based tool that can automatically detect the left-turning vehicles (right-hand traffic rule) at signalized intersections and extract their trajectories from a recorded video. The proposed tool uses a region-based CNN trained over a limited number of video frames to detect moving vehicles. Kalman filters are then used to track the detected vehicles and extract their trajectories. The proposed tool achieved an acceptable accuracy level when verified against the manually extracted trajectories, with an average error of 16.5 cm. Furthermore, the trajectories extracted using the proposed vehicle tracking method were used to demonstrate the applicability of the minimum-jerk principle to reproduce variations in the vehicles’ paths. The effort presented in this paper can be regarded as a way forward toward maximizing the potential use of deep learning in traffic safety applications.