A Review on the Use of Bitumen Stabilised Material (recycled Asphalt) for Road Construction in Nigeria

ABSTRACT
The increasing demand for cost-effective, durable, and sustainable road infrastructure has led to the exploration of alternative materials and techniques in pavement construction. Bitumen-Stabilized Materials (BSMs), which involve the use of foamed bitumen or bitumen emulsion to enhance the engineering properties of marginal soils or recycled aggregates, have emerged as a viable alternative to traditional granular base and sub-base layers. This study presents a comprehensive review of the application, performance, and challenges associated with BSMs in road construction, with a particular focus on developing countries such as Nigeria. The research employed a systematic literature review methodology, drawing from peer-reviewed journals. Technical reports, standards, and case studies spanning both developed and developing countries. The analysis reveals that BSMs exhibit superior mechanical properties, including improved unconfined compressive strength, moisture resistance, and fatigue performance compared to unbound materials. Additionally, BSMs enable the reuse of reclaimed asphalt pavement (RAP) and in-situ soils, contributing significantly to sustainability through reduced material consumption and lower carbon emissions. Despite their proven benefits, the adoption of BSMs is limited by a lack of standardized design guidelines, insufficient local expertise, and the scarcity of long-term field performance data in tropical regions. The study recommends the development of national standards, pilot projects, capacity-building initiatives, and integration of BSM research in academic institutions to foster wider adoption. Overall, the review concludes that BSMs offer a promising pathway toward resilient and environmentally sustainable road networks, especially in regions facing financial and material resource constraints. Their successful implementation requires coordinated efforts among policymakers, engineers, researchers, and contractors to overcome existing barriers and unlock the full potential of this technology.

Keywords: Bitumen-stabilized materials, foamed bitumen, road construction, RAP, pavement design, sustainability. Nigeria, pavement rehabilitation