Transforming Bridge Construction With Innovative Building Materials
Dr S B Hegde reviews recent advancements in sustainable materials, their properties, applications, benefits, and prospects in India’s bridge construction industry.

In bridge constructions, while traditional materials like steel and conventional concrete have been effective, their environmental impact through high carbon emissions and resource-intensive manufacturing is increasingly concerning. In response, the industry is turning to innovative and sustainable materials that promise to reduce environmental impact while improving the performance and longevity of bridge structures.
Ultra-High-Performance Concrete (UHPC)
UHPC is known for its exceptional mechanical properties, featuring compressive strengths over 150 MPa. Its dense microstructure is enhanced with fine powders like silica fume, ultra-fine fly ash, as well as fibers, contributing to its superior strength and ductility.
UHPC is ideal for high-stress and harsh environmental conditions. Research indicates that UHPC can extend bridge lifespan by up to 50%, reducing maintenance frequency and costs.
For example, the Mars Hill Bridge in Iowa, USA, has utilized UHPC for deck slabs and joints, reducing material use by 30% and projecting a service life exceeding 100 years.
The Seoul-Busan High-Speed Railway in South Korea, has employed UHPC for viaducts, demonstrating its increased resistance to seismic activity and extreme weather.
In India, UHPC is being explored for key infrastructure projects under the Bharatmala Pariyojana. A pilot project in Gujarat has shown that UHPC improves durability and could reduce construction costs by 25%.
UHPC reduces carbon emissions by approximately 25% by replacing up to 60% of traditional concrete, through lower cement consumption and enhanced durability.

Geopolymer Concrete
Geopolymer concrete is an eco-friendly alternative activated with alkaline solutions and typically uses by-products like fly ash and blast furnace slag. It offers high compressive strengths (50-100 MPa), excellent fire resistance, and superior chemical durability. It performs comparably to or better than traditional concrete, with a significantly lower environmental impact, particularly in aggressive environments.
For example, the West Gate Bridge in Melbourne, Australia, has used geopolymer concrete in repair works, reducing carbon emissions by 40%.
The Dhaka Flyover in Bangladesh implemented geopolymer concrete for critical structural elements, improving durability against corrosion.
In India, Geopolymer concrete is being used in bridges in coastal regions and in areas with high corrosion rates. Projects in Tamil Nadu have demonstrated significant improvements in durability and a projected 80% reduction in CO2 emissions compared to traditional Portland cement. Geopolymer concrete can cut CO2 emissions by up to 80% by incorporating industrial byproducts and reducing reliance on energy-intensive cement production.

Fibre-Reinforced Polymers (FRP)
FRPs use high-strength fibers embedded in a polymer matrix, offering lightweight, corrosion-resistant, and high tensile strength-to-weight ratios. They are ideal for reinforcing bridge components. FRP-reinforced bridges experience up to a 30% reduction in lifecycle costs due to lower maintenance needs and enhanced durability.
For example, the Henningsen Bridge in Denmark used carbon FRP reinforcement for a maintenance-free structure with an expected lifespan of over 100 years.
The Stork Bridge in the Netherlands features glass FRP components, showing resilience against harsh weather and reducing costs by 25%.
In India, FRP is being used in the reinforcement of bridges in coastal regions like Mumbai, where FRP reinforcement has demonstrated improved durability and a 20% reduction in maintenance costs. FRPs reduce the need for steel reinforcement, addressing corrosion issues and extending bridge service life, leading to a reduction in material consumption and carbon emissions.

Advanced Cementitious Materials
Ground Granulated Blast Furnace Slag (GGBS): GGBS enhances concrete's durability, reduces permeability, and improves chemical resistance. Incorporating 40% GGBS can increase compressive strength by 25%.
Fly Ash and Ultra-Fine Fly Ash: Fly ash improves workability and long-term strength, while ultra-fine fly ash contributes to a denser microstructure. For example, 15% ultra-fine fly ash in UHPC enhances compressive strength by 25%.
Silica Fume: Silica fume is used to achieve dense matrices in UHPC, typically incorporated at 5-10%, allowing for compressive strengths above 150 MPa.
GGBS, fly ash, and silica fume are widely used in Indian bridge projects, such as those under the Bharatmala Pariyojana. Pilot projects in Karnataka show that using 20-30% SCMs in concrete can save nearly 1.5 million tons of CO2 annually and reduce construction costs by 25%.
Advanced cementitious materials reduce environmental impacts by replacing significant portions of Portland cement, lowering CO2 emissions, and utilizing industrial byproducts.

Uncommon Sustainable Materials
Rice Husk Ash (RHA): RHA enhances strength and reduces water absorption, with Indian bridges successfully using 15% RHA replacement to improve durability.
Sugarcane Bagasse Ash (SCBA): SCBA offers sulfate resistance and reduced permeability, with 20% SCBA replacement maintaining comparable compressive strengths to conventional concrete.
Palm Oil Fuel Ash (POFA): POFA enhances compressive strength and resistance to alkali-silica reactions, with 20% POFA replacement showing significant improvements.
Mining Waste: Mining tailings can replace up to 50% of natural aggregates. South Africa uses copper tailings effectively in concrete.
Marble Powder: Marble powder improves compressive strength and reduces water absorption.
Construction Debris: Recycled construction and demolition waste can substitute virgin aggregates. The Karlsruhe Highway Bridge in Germany uses 50% recycled aggregates.
RHA and SCBA are used in rural and high-humidity regions. Tamil Nadu bridges that have used RHA have shown durability improvements, while SCBA use has reduced construction costs by 20%. These materials promote recycling, reduce demand for virgin resources, and address waste disposal challenges, contributing to a circular economy.
Bamboo as Reinforcement: Bamboo is a sustainable alternative to steel reinforcement, known for its high strength-to-weight ratio and rapid renewability. Bamboo-reinforced concrete is particularly beneficial in seismic regions.
Pilot projects have used bamboo-reinforced concrete for bridges, demonstrating cost reduction and sustainability. For example, the Philippine Bamboo Bridge has used bamboo strips as reinforcement for pedestrian traffic. The Colombian Rural Bridge Project has used bamboo-reinforced concrete for enhanced accessibility.

In India, bamboo reinforcement is being explored for small to medium-span bridges in rural areas. Initial projects in the North-Eastern states of India show promise in cost reduction and sustainability. Bamboo's lower embodied energy compared to steel results in a 30% reduction in environmental footprint for bamboo-reinforced bridges.
Self-Healing Concrete: Self-healing concrete contains encapsulated bacteria or chemical agents that activate upon crack formation, sealing cracks autonomously and extending the lifespan of structures.
Self-healing concrete reduces crack propagation by 70%, extending bridge service life by 50%, and is beneficial in fluctuating temperatures and moisture conditions.

For example, the Schaalsmeerdijk Bridge in the Netherlands, has used self-healing concrete to reduce maintenance needs. The Tokyo Sky Bridge in Japan has incorporated bacteria-based self-healing concrete for improved seismic resistance.
Self-healing concrete is being trialed in Gujarat and Maharashtra, with early results indicating a 50% reduction in maintenance costs. Self-healing concrete also reduces maintenance frequency and conserves resources, lowering lifecycle costs by up to 50%.

Albedo Concrete: Albedo concrete features a high reflectance surface, reducing heat absorption and lowering ambient temperatures. It is beneficial in mitigating the urban heat island effect. It can lower surface temperatures by up to 5°C, improving comfort and reducing cooling costs for adjacent structures.
In India, Albedo concrete is being considered for use in bridge decks and pavements in urban areas to mitigate heat island effects. Initial trials in cities like Bangalore have shown promise in reducing surface temperatures as Albedo concrete contributes to urban cooling. It also helps in reducing energy consumption for air conditioning and improving the overall environmental comfort.

Insulating Concrete: Insulating concrete incorporates thermal insulating materials, improving energy efficiency and temperature regulation in structures.
Insulating concrete can reduce energy consumption for heating and cooling by up to 30%, making it suitable for bridges in areas with extreme temperature variations. In India, insulating concrete is being explored for bridges in the cold regions of North India and in high-altitude areas to enhance thermal performance and reduce maintenance needs. Insulating concrete contributes to energy efficiency and lowers operational costs by minimizing temperature fluctuations and energy use.

Way Forward for India
- Expand the use of sustainable materials through pilot projects to demonstrate their benefits and overcome implementation challenges.
- Develop and update regulatory frameworks and standards to facilitate adoption of these materials in bridge construction.
- Encourage research into new materials and technologies to stay ahead of emerging trends.
- Foster collaboration between government, industry, and academic institutions to drive innovation and implementation.
- Provide training for engineers and contractors on the benefits and applications of new materials.
- Implement incentives and support mechanisms to encourage use of sustainable materials and practices in bridge construction.
References
- ACI Committee 318. (2022): Building Code Requirements for Structural Concrete. American Concrete Institute.
- Jones, M. R., & McCarthy, M. J. (2021): Advancements in Geopolymer Concrete. Construction and Building Materials Journal.
- Smith, A., & Schiessl, G. (2020): Performance of Fiber-Reinforced Polymers in Bridge Rehabilitation. Journal of Bridge Engineering.
- Kumar, R., & Sharma, V. (2023): Use of Ground Granulated Blast Furnace Slag in Sustainable Concrete. Indian Journal of Civil Engineering.
- Sharma, P., & Singh, R. (2022). *Rice Husk Ash in Concrete: A Review*. Materials Science Forum.
- Wang, H., & Zhang, L. (2021). *Self-Healing Concrete: Mechanisms and Applications*. Construction Materials Journal.
- Gupta, A., & Rao, S. (2024). *Albedo Concrete for Urban Heat Island Mitigation*. Journal of Urban Environmental Engineering.
- Patel, J., & Saini, S. (2023). *Insulating Concrete in Extreme Climate Conditions*. Journal of Building Performance.
About the author

Dr S B Hegde is Professor at Department of Civil Engineering, Jain College of Engineering, India and Technology, Hubli, and Visiting Professor, Pennsylvania State University, USA. He has over 30 years of experience in the Cement Industry, has authored 215 research papers, holds six patents, and has filed four US patents in 2023. He advises the Indian government on hydrogen in cement, gives consultancy to major cement companies, and serves on the editorial board of key industry journals. He was honored with the 'Global Visionary' award by the Gujarat Chambers of Commerce and Industry.