Utilising Old Pavement for New Construction

A Case Study of Udaipur-Sabroom section, Tripura by Dr Siksha Swaroopa Kar, Principal Scientist, CSIR-CRRI, and Dr Devesh Tiwari, Former Chief Scientist, CSIR-CRRI

Road infrastructure serves as the lifeline of transportation networks, playing a pivotal role in fostering economic growth, regional integration, and societal advancement. However, the durability of pavements inevitably deteriorates over time due to various factors such as traffic loads, environmental conditions, and material aging. Consequently, the rehabilitation or reconstruction of existing roadways becomes imperative to ensure continued functionality and safety.

Innovative approaches have emerged to optimize resources, enhance sustainability, and improve the longevity of road infrastructure. One such approach involves the utilization of old pavement materials in the construction of new road surfaces, coupled with advancements in base stabilization techniques such as foam bitumen technology.

 

This case study explores the application of this innovative approach in the context of the Udaipur-Sabroom section of National Highway 44, located in the scenic landscapes of Tripura. Spanning from kilometer 55.00 to kilometer 128.72, this vital transportation corridor has been subject to development works carried out by the National Highways and Infrastructure Development Corporation Limited (NHIDCL).

Challenges and Opportunities:

The project presents a unique set of challenges, including the need for pavement rehabilitation, limited availability of construction materials, and the desire for sustainable infrastructure solutions. Traditional methods of pavement reconstruction often entail significant resource consumption and environmental impact. However, by harnessing the principles of FBM and incorporating old pavement materials, we can mitigate these challenges and capitalize on the opportunities for sustainable development.

The utilization of old pavement materials for new construction presents a viable and sustainable solution for pavement rehabilitation and reconstruction projects. Through careful assessment, design optimization, and implementation, road authorities can pave the way towards a greener and more efficient transportation network.

Utilizing Old Pavement Materials:

The cement treated sub-base layer using brick aggregate was laid followed by foam stabilised base layer.  The concept of utilizing old pavement materials involves reclaiming existing pavements and incorporating them into the construction of new pavements. This process not only conserves natural resources but also reduces construction costs and environmental footprint. In the case, the existing pavement materials was reclaimed, processed, and treated with foamed bitumen in plant to lay the stabilised base layer.

Feasibility and Technical Considerations:

The feasibility of utilizing old pavement materials for new construction depends upon several technical considerations. Firstly, the properties of reclaimed materials, including gradation, strength, and durability, must be assessed to ensure compatibility with foamed bitumen stabilization. Laboratory optimisation of foam parameter, i.e expansion ratio and half-life is carried out at different binder temperature and foaming water content.

The gradation of the aggregate blend was tailored to meet the requirements outlined in IRC 37:2012, with the addition of cement filler to enhance cohesion. Optimum moisture content (OMC) was determined through modified proctor compaction tests, facilitating the achievement of maximum dry density for the untreated materials. Foamed bitumen, prepared using VG-10 binder, was incorporated into the mixtures at varying binder contents, ranging from 2.0% to 2.5% by weight of aggregate. Mechanical testing, including dry and wet Indirect Tensile Strength (ITS) and resilient Modulus, was conducted to the suitability of reclaimed materials for new pavement construction.

Details of mix design parameters used for this study is given here.

Benefits and Sustainability:

The utilization of old pavement materials for new construction offers numerous benefits from both economic and environmental perspectives. By reducing the reliance on virgin aggregates and bitumen, project costs can be significantly lowered, resulting in cost savings for stakeholders. Furthermore, the conservation of natural resources and reduction of construction waste contribute to environmental sustainability.

Moreover, the incorporation of foamed bitumen stabilization enhances the mechanical properties and longevity of pavements, ensuring durable and resilient infrastructure. The project stands to benefit from improved pavement performance, reduced maintenance requirements, and enhanced service life, thereby enhancing the overall quality of transportation infrastructure in the region.