Quantifying Road Construction Waste: Lessons from Sri Lanka for Sustainable Infrastructure
By Eng(Dr). Ganila N. Paranavithana
Roads are often presented as visible markers of national progress. They link rural communities to markets, enable mobility, and support economic growth, particularly in developing economies where infrastructure investment is seen as a catalyst for development. Yet beneath the finished surface of these roads lies a largely overlooked challenge: the generation of construction waste. While construction and demolition waste has been widely studied in the context of buildings, waste generated during road construction has received comparatively little attention, despite the sector’s scale and material intensity. This gap is especially pronounced in developing countries, where limited data availability, weak waste management systems, and informal disposal practices obscure the true magnitude of the problem. Sri Lanka provides a compelling case through which this issue can be examined, offering insights that are broadly applicable across many developing economies.
Globally, construction and demolition waste is estimated to account for approximately 30 percent of total annual waste generation, a figure that can rise to nearly 50 percent in rapidly urbanizing developing countries. Road construction contributes substantially to this burden due to the extensive use of aggregates, asphalt, binders, and earthworks. Improper handling and disposal of these materials lead to environmental pollution, depletion of natural resources, public health risks, and unnecessary economic losses. In many developing contexts, waste from road projects is rarely quantified at disposal sites, partly because such facilities are scarce and partly because a significant proportion of waste is disposed of informally. As a result, policymakers and practitioners are often forced to rely on assumptions rather than evidence when planning projects or designing waste management strategies.
In Sri Lanka, road construction has dominated the construction sector for more than a decade, driven by government policies focused on regional connectivity and rural development. Prior to the recent economic crisis, the construction industry contributed between eight and ten percent of national GDP, with roads and railways accounting for nearly 44 percent of total construction output. Despite this prominence, systematic management of road construction waste has not been established. One of the most significant barriers has been the absence of reliable statistics on material wastage during construction. Without such data, it is difficult to implement best environmental management practices, promote circular economy principles, or meaningfully reduce greenhouse gas emissions associated with infrastructure development.
Against this backdrop, an extensive empirical study was undertaken to quantify material wastage during road surfacing and sub-base construction in Sri Lanka’s southern province. The research analyzed data from 245 road construction projects completed during 2021 and 2022, from which 58 representative projects were selected for detailed investigation. These projects covered all contractor grades defined by the Construction Industry Development Authority, ranging from highly capable firms with substantial financial and technical resources to small-scale contractors handling minor works. This diversity allowed the study to examine not only the scale of material wastage, but also how contractor capacity influences waste generation.
Given the limitations of measuring waste at disposal sites in developing countries, the study adopted a material waste factor approach. Material waste was calculated as the difference between quantities issued from contractors’ storehouses and the actual quantities required based on on-site measurements of completed work. This method enabled waste estimation using records that contractors and road authorities already maintain, making it both practical and transferable to similar contexts. Statistical validation was applied to ensure acceptable precision levels, and the analysis ultimately focused on three materials that dominate road construction activities: aggregate base course, wearing course asphalt concrete, and cationic slow setting emulsion. Together, these materials were used in more than 80 percent of the road projects examined.
The results reveal that material wastage is a consistent and non-trivial feature of road construction. Across all contractor grades, aggregate base course exhibited the highest levels of waste, followed by cationic slow setting emulsion and wearing course asphalt. The mean material waste factors were found to be approximately 8.7 percent for aggregate base course, 6.8 percent for cationic slow setting emulsion, and 5.2 percent for wearing course. These figures indicate that a significant proportion of materials purchased for road projects ultimately becomes waste, representing avoidable costs and unnecessary environmental impacts. Statistical analysis showed considerable variability, particularly for aggregate base course, suggesting inconsistent material handling practices and quality control across projects.
One of the most striking findings of the study is the relationship between contractor capacity and material wastage. Higher-grade contractors consistently demonstrated lower waste factors, while smaller, lower-grade contractors exhibited higher and more variable levels of wastage. This trend suggests that waste generation is not merely a technical issue but is closely tied to management practices, planning capability, and access to skilled labor and equipment. Contractors with stronger financial and technical capacity appear better able to control material usage, implement quality assurance measures, and respond effectively to site-level uncertainties. Conversely, resource-constrained contractors may rely on conservative over-ordering and less precise construction methods, leading to higher waste generation.
Beyond quantifying waste, the study makes a significant contribution by developing predictive tools that allow waste generation to be estimated in advance. Strong linear relationships were identified between the total quantity of materials used and the amount of waste generated. After rigorous statistical testing, reliable predictive equations were developed for cationic slow setting emulsion and wearing course asphalt. These equations enable practitioners to estimate expected waste based on planned material quantities, providing a valuable tool for procurement planning, cost control, and environmental management. Verification using independent project data confirmed the robustness of these models within the defined context of contractor capacity, construction methods, and standards based on Road Note 31, which is widely used in tropical and sub-tropical regions.
The implications of these findings extend well beyond Sri Lanka. Many developing countries face similar challenges: rapid expansion of road networks, limited waste management infrastructure, and a lack of empirical data to inform sustainable practices. By demonstrating a practical, data-driven approach to quantifying and predicting road construction waste, this research offers a replicable framework for other regions. Material waste factors can serve as benchmarks for industry performance, inform contractor selection and specification processes, and support policy interventions aimed at reducing waste and promoting resource efficiency.
Reducing material wastage in road construction also has important implications for climate change mitigation. The construction sector accounts for more than one-third of global greenhouse gas emissions, with road construction responsible for a substantial share. Every reduction in wasted aggregate, asphalt, or binder translates into lower emissions from material extraction, processing, and transport. In this sense, waste reduction is not only a matter of cost efficiency but a critical component of sustainable infrastructure development.
The study is not without limitations. Data collection was constrained by the scale of road projects, the self-financed nature of the research, and the reluctance of some contractors to share detailed records. As a result, only a subset of projects could be analyzed in depth. Additionally, the findings are based on construction methods aligned with specific standards, and waste factors may vary under different technical or regulatory conditions. These limitations point to opportunities for future research, including the examination of other pavement types, additional waste streams such as soil and concrete debris, and comparative studies across regions and construction methodologies.
Nevertheless, the findings provide a strong foundation for improving material wastage management in road construction. By making waste visible and measurable, the research transforms an overlooked problem into a manageable one. Construction companies can use these insights to benchmark their performance, optimize material procurement, and adopt more sustainable practices. Policymakers can incorporate waste factors into guidelines, incentives, and regulatory frameworks that encourage efficiency and accountability. Ultimately, the study underscores a simple but powerful principle: sustainable roads are not defined solely by their durability or alignment, but by how responsibly they are built. In developing economies where infrastructure investment remains a priority, managing road construction waste is no longer optional—it is an essential step toward building a more resilient, resource-efficient, and sustainable future.
References;
Paranavithana, G. N., Samarakoon, S. M. K., & Chathurika, R. H. J. (2024). Analysis of road construction waste generation in developing economies: A focus on surfacing and sub-base construction projects in Sri Lanka. Journal of Cleaner Production, 457, 142465. https://doi.org/10.1016/j.jclepro.2024.142465
Dr. Ganila N. Paranavithana has obtained his primary education from Kadugannawana Primary School and his secondary and tertiary education from St/Sylvester’s College Kandy. After the G.C.E Advanced Level examination, he entered the Faculty of Engineering of the University of Peradeniya, which led him to obtain his degree in Bachelors of Sciences in Civil Engineering. After completing his degree, he has worked in several local and international institutions before getting his post-graduate qualifications. Dr. Paranavithana obtained his Master degree in Environmental Pollution Control Engineering from the Faculty of Engineering, University of Peradeniya in 2012, which led him to apply for a Ph.D. As soon as he completed his MSc, he won the Japanese government Scholarship to read for his Ph.D. at Saitama University, Japan. He has specialized in Geoenvironmental Engineering, which is a highly developing field in the world. Dr. Paranavithana is currently working as a Senior Lecturer attached to the Department of Civil Engineering of the Open University of Sri Lanka.