Bangladesh Rethinks Highway Materials: From Dependence on Bitumen to Resilience of Concrete

According to WPB, Bangladesh is currently making a significant policy change in its road infrastructure with a gradual move away from bitumen pavement and towards cement concrete highways. The change is being driven by concerns over long-term sustainability, maintenance cost, and the limitation of bitumen in a country's severe climatic and traffic conditions.

Referral for Change from Bitumen

For more than four decades, bitumen, a petroleum product, has been the cornerstone of Bangladesh's flexible pavement system. Although comparatively inexpensive to build, bitumen roads are very much dependent on imported raw materials and are highly susceptible to environmental stress. The Roads and Highways Department (RHD) has stated that flexible pavements made from ordinary bitumen or Polymer Modified Bitumen (PMB) require not less than four large-scale maintenance operations within a 20-year life span, as well as routine patchwork. These roads are rapidly destroyed by heavy truckloads, floods in summer, and heat during summer, and they are thus costly for their whole life cycle.

Conversely, rigid pavements use locally sourced cement, sand, and stone. As much as 10–15% higher in initial construction costs compared to bitumen, concrete pavements have service lives of 20–30 years with minimal need for repair. Their resistance to Bangladesh's monsoon waterlogging and climatic extremes has made them increasingly popular.

Ongoing Projects and Policy Directives

The shift from bitumen is already in the pipeline. In the Elenga–Hatikamrul–Rangpur highway expansion project, nearly half of the 190 km road has already been constructed with concrete, and the remaining half still relies on bitumen. Similarly, along the Dhaka–Sylhet corridor, a pilot stretch of 11 km is being developed through concrete instead of bitumen, a move that will save Tk54 crore in the long term.

Government policy is working to fuel this trend. On the instruction of the Chief Adviser's Office, RHD has been mandated to raise rigid pavement construction on a nationwide scale. Engineers note that although sections of the Dhaka–Chattogram highway topped with bitumen have failed fast under waterlogging, nearby concrete sections—particularly around toll booths and marketplaces—are intact.

Expert Views on Bitumen vs. Concrete

According to Bangladesh University of Engineering and Technology (BUET) Prof. Shamsul Haque, bitumen's limitations make concrete a strategic imperative rather than an engineering choice. He emphasizes that while bitumen is still good for some short-span or low-traffic jobs, its vulnerabilities when subjected to heavy loadings and climatic stress render it less sustainable for national highways and expressways. Using India's 2017 decision to completely shift away from bitumen use in new highways as a reference, Prof. Haque is urging Bangladesh to pursue a similar policy trajectory.

Relative Performance

Flexible pavements made of bitumen have some disadvantages: they become soft at high temperatures, are prone to cracks at low temperatures, and are weakened by prolonged rain. High traffic accelerates rutting and surface settlement, resulting in more maintenance requirements. Even PMB, while more advanced, still requires frequent maintenance.

Concrete pavements, however, eliminate most of these issues. Their rigidity does away with wheel depressions, conserves truck fuel by up to 20%, and reflects more light, enhancing visibility and safety. Additionally, the lighter surface absorbs less heat, aiding to mitigate the urban heat island effect, a growing problem in Bangladesh's cities.

Lessons from Around the World in Reducing Bitumen Dependency

This shift away from bitumen is not something unique to Bangladesh. The United States began adopting concrete roads beginning in the 1970s when oil shocks exposed the vulnerability of petroleum-dependent bitumen supply chains. Similarly, India's 2017 nationwide ban on the building of new bitumen-based roads was a clear response to degraded road life in a monsoon climate. Such instances highlight that while bitumen is a good construction material, excessive use in critical transport corridors can cause economic waste.

Local Practice in Use of Concrete

Rigid pavements have already been proved feasible by Bangladesh. Roads of BUET campus, improved drastically from bitumen to concrete in 1996, have required little or no maintenance for decades, in contrast to the erstwhile bitumen surfaces that were regularly repaired. This case study documents the long-term sustainability advantage of reducing dependency on bitumen in the national highway system.

Conclusion

Bangladesh road infrastructure policy is changing from bitumen-based practices towards an even approach providing emphasis to concrete where strength and longevity are of paramount concern. While bitumen still finds application in some flexible pavement applications, its susceptibility to environmental and traffic forces highlights the need for alternative procedures. By reducing reliance on imported bitumen and employing domestically produced cement-based substitutes, Bangladesh is trending towards international best practices and delivering stronger, cost-efficient, and sustainable roads for the future.

By Bitumenmag

Bitumen, Road, Pavement