Utilization of demolished concrete waste for roller compacted concrete pavement (RCCP) applications

Abstract

Roller Compacted Concrete (RCC) has gained popularity in concrete pavement applications owing to its strength, durability, and cost-effectiveness. However, due to the growing scarcity of natural aggregates, sustainable alternatives for natural aggregates are in demand. This study explores the use of Recycled Concrete Aggregates (RCA) obtained from demolished concrete waste in RCC pavement applications, aiming to assess its mechanical performance. The research explores the most suitable compaction method for optimum moisture content (OMC) determination for RCC, the influence of RCA quality improvements on RCC properties and the impact of using clay tile aggregates (CTA) for internal curing. Various compaction methods, such as the Standard Proctor Test (SPT), Modified Proctor Test (MPT), Vibratory Hammer Test (VHT) and Modified Vebe Test (MVT), were analysed to determine the most suitable OMC for RCC mix design with RCA (RCC_RCA) and virgin crushed aggregates (RCC_VCA). VHT and MVT emerged as suitable methods for OMC determination of RCC. The study also compared the performance of RCA treated through various methods: surface coating with fly ash (FA), surface coating with sugarcane bagasse ash (SCBA), and ball milling. Results revealed that ball milling RCA significantly improved aggregate quality by reducing water absorption and porosity. RCC with 100% ball- milled RCA and cement showed increased strength, nearly matching the performance of RCC made with VCA. The incorporation of waste CTA in RCC mixes enhanced early-age (3-day) compressive strength by 13-18% compared to externally cured RCC, owing to the benefits of internal curing. However, it showed a reduction in long-term compressive strength in comparison to externally cured conventional RCC. Tensile and flexural strength also slightly declined with the inclusion of CTA. Uncured RCC specimens with CTA performed better than uncured RCC specimens without CTA in terms of all mechanical properties. These findings indicate that RCA can be successfully utilised in RCC pavements, and internal curing using CTA as fine aggregates at a replacement percentage of 5% will provide significant benefits for the early hydration of RCC. The study contributes to the scientific knowledge of sustainable construction practices and provides practical recommendations for incorporating RCA in RCC and alternative curing techniques for RCC pavements.