Assessment of Carbon Emissions of Road Projects and Development of a Framework for Carbon Footprint Calculation of Roads in the City Of Abu Dhabi

Climate change has become a global issue affecting the environment and human health. Transportation is a major contributor of greenhouse gases (GHG) emissions, with road transport being responsible for more than half of these emissions. The main objective of this thesis was to estimate the carbon footprint associated with road projects in the city of Abu Dhabi following a comprehensive approach that considers all activities within the life cycle of roads. Three cases were considered including, Al Rahba City internal road network, the upgrading of Al Salam Street, and the widening of the Eastern Corniche Road. A carbon footprint estimation model (referred to as RoadCO₂) was developed to estimate GHG emissions of the three road cases. The model considers emissions from all phases of road projects and reports emissions in terms of carbon dioxide equivalent (CO₂eq). The methodology suggested by the Intergovernmental Panel on Climate Change (IPCC) was adopted in constructing the model. Results revealed that the total emissions from the construction of the investigated road cases are about 43, 292, and 16 thousand tons CO₂eq, respectively. Equipment used in construction contributed about 70%, 15% and 21% of the total emissions of the construction phase, respectively. The rest of the emissions during the construction phase originated from the use of construction materials and their associated transport. Upgrading of Al Salam Street project produced the highest emissions from construction materials due to the construction of a tunnel. Annual total emissions during the operation phase of Al Salam Street was estimated to be over 108 thousand tons CO₂eq/yr, whereas emissions during the operation phase for Al Rahba City internal roads were about 15 thousand tons CO₂eq/yr, and those for the Corniche Road were 91 thousand tons CO₂eq/yr. For the three cases, emissions were generated mainly during the operation phase (94% or more), with the main contributor being vehicle movement, followed to a lesser extent by street lighting

Environmental and Economic Life Cycle Assessment of Recycled Aggregates Concrete in the United Arab Emirates

This paper studies the potential environmental and economic impact of replacing natural aggregates (NA) with recycled aggregates (RA) in the production of different sustainable concrete mixes in the United Arab Emirates (UAE). A life cycle assessment (LCA) was carried out according to the methodology proposed by the international standards of the series ISO 14040. The performance of concrete mixes having a similar design compressive strength was evaluated. Results showed that the inclusion of steel fibers (SF) led to an increase in the global warming potential (GWP), whereas mixes with cement replacement by fly ash, slag, or microsilica recorded a reduction in GWP. Furthermore, SF-reinforced mixes created with 100% RA were at least three times more expensive than the NA-based control mix, while the cost of those with cement replacement by mineral additives was generally similar to that of the control. Material transportation was found to be a main contributor to the environmental and economic impacts, only second to cement, and its contribution increased with longer distances and steel fiber incorporation and decreased with RA replacement. To integrate these individual measures and select optimum mixes for various applications, multifunctional performance indices were developed. Research findings highlight the possibility to fully replace NA with RA (100%) while maintaining the performance and improving the economic and environmental impacts of concrete produced in the UAE

A Bibliometric Analysis of the Studies on Self-Healing Concrete Published between 1974 and 2021

Research on self-healing concrete has flourished in recent years. This paper aims to comprehensively understand the current research situation and future development directions of self-healing concrete. It summarizes and analyzes the publications on self-healing concrete from 1974 to 2021 to reveal the current key research topics and development trends and identifies the most productive research constitutes. The bibliometric analysis software Biblioshiny was used to analyze 1433 documents written by 2961 authors and published in 450 sources retrieved from Scopus. The analysis included an overview of the leading information and an analysis of the authors, countries, universities/institution, publications, and keywords. Results obtained from the author analysis suggest that tracking the work of the most productive authors is essential, as it will provide researchers with valuable information, such as possible leads and ideas for future research work and collaboration opportunities. Countries, universities/institutes, and publications analysis revealed that more collaboration leads to more exposure and a higher citation rate, significantly promoting self-healing research development. A keywords analysis highlighted the focus areas in self-healing concrete and presented potential gaps in the literature. The findings of this study will provide scholars with a comprehensive understanding of the current research work in the field of self-healing concrete and its future directions. Results can also benefit stakeholders in making effective decisions to direct the development of the self-healing industry

GHG Emission Reduction Opportunities for Road Projects in the Emirate of Abu Dhabi: A Scenario Approach

The transportation sector is considered one of the driving forces behind the increased release of greenhouse gases (GHGs), with road transport being this sector’s main emissions contributor. In turn, efforts should be devoted to reducing emitted GHGs from this sector, and many such opportunities lie in the road transport life cycle. This paper investigated fourteen emission reduction scenarios based on the green initiatives issued by the Abu Dhabi Government. The explored measures are either related to road works and road municipal services or to traffic movement. The proposed measures were evaluated with reference to a baseline study previously reported by the authors for three different road projects in Abu Dhabi city. Findings reveal that normalized GHG emission reduction could be significantly reduced by (i) replacing 30% of internal combustion engine passenger cars with battery electric vehicles where the power demand is covered almost equally from nuclear and liquified natural gas (LNG) sources, (ii) reducing the number of passenger cars by 10%, and (iii) having one-fifth of passenger cars powered by LNG. A lesser significant reduction could be achieved by replacing conventional lamps with light-emitting diode (LED) lamps or by having one-fourth of lighting powered by solar energy. Even lesser reduction could be achieved by (i) replacing a portion of Portland cement with ground granulated blast furnace slag in concrete structures, (ii) fully utilizing treated sewage effluent for roadside-plant irrigation, (iii) reducing desalinated water used for roadside-plant irrigation by 20%, and (iv) increasing the number of higher efficiency passenger cars by 10%. Replacing hot-mix asphalt with warm-mix asphalt and using asphalt with a high stiffness modulus in the base layer results in low emission reduction. The use of 15% recycled asphalt or the use of 50% recycled aggregate in road construction has the least impact on emission reduction. When all explored scenarios were combined, an overall normalized GHG emissions reduction of 9–17% during the road project life cycle could be achieved

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RoadCO2: a web-based tool for estimation of greenhouse gas emissions of road projects

A number of countries have recognized the need to quantify the greenhouse gas (GHG) emissions produced by road transportation. As a result, several estimation tools have been developed during the last decade. However, the available tools do not capture all activities contributing to GHG emissions during the life cycle of road projects. This paper describes the development of a comprehensive web-based tool that can be used to quantify direct and embodied emissions from all activities associated with different phases of road projects. The tool, called RoadCO2, accounts for all possible activities that may be encountered during the pre-construction, construction, operation, maintenance, and rehabilitation phases of a road project. Although RoadCO2 currently uses emission factors established by the Intergovernmental Panel on Climate Change (IPCC), the tool has the flexibility to accommodate country-specific emission factors, if available