PERFORMANCE STUDY ON STRENGTH AND CBR CHARACTERISTICS OF FLEXIBLE PAVEMENT LAYERS STABILIZED WITH CRUSHER DUST AND WASTE TYRE MATERIALS

– The increasing demand for cost-effective and sustainable pavement construction has led to the exploration of alternative materials capable of improving structural performance while reducing environmental impact. This study investigates the applicability of crusher dust (CD) and waste tyre derivatives—ground granulated waste tyre (GGWT) and crumb rubber waste tyre (CRWT)—for use in various layers of flexible pavements. Crusher dust was segregated into three particle size ranges (coarse: 4.75–2 mm, medium: 2–0.425 mm, and fine: 0.425–0.075 mm), and a total of 194 gradation mixes were prepared to evaluate their compaction and California Bearing Ratio (CBR) characteristics. Experimental results showed that single-sized mixes yielded CBR values between 8–11%, two-sized mixes between 10–10.5%, and well-graded mixes between 13–15%. Field samples collected from North Coastal Andhra Pradesh exhibited an error range of –8.33% to 18.18%, validating laboratory findings. For sub-base and base course investigations, MoRT&H specifications were adopted. Optimum gradation using 26.5 mm aggregate with 40% crusher dust resulted in CBR values of 48–68%. Further improvement was observed with the inclusion of GGWT (0.5–3%), which elevated CBR values to 48–82%, with optimum performance at 1.5–2%. Additionally, MoRT&H granular base gradations (GB12–GB13) achieved CBR values of 128–138%, indicating suitability for high-strength base applications. CRWT-modified base mixes demonstrated enhanced toughness and resilience at varying particle sizes (10 mm, 20 mm, 30 mm). The study concludes that the combined use of crusher dust and waste tyre derivatives enhances strength, durability, and cost efficiency of flexible pavement layers, establishing their suitability as sustainable alternatives in pavement construction.