Fundamental Characterisation of Modified Cold Mix Asphalt Mixtures

Abstract

Cold Mix Asphalt (CMA) presents a sustainable alternative for road construction, however its usage is deterred by challenges such as weaker early life strength and longer curing times compared to Hot Mix Asphalt (HMA). These issues are addressed within the thesis by investigating the incorporation of Recycled Cellulose Pellets (RCP) and a combination of Ground Granulated Blast-Furnace Slag and Calcium hydroxide (GC) filler as sustainable modifiers to improve CMA’s performance.
The study investigates the chemical consistency and absorption properties of RCP, observing its consistent chemical properties despite being sourced from different locations, eliminating concerns of contamination or variability. The impact of curing temperature on RCP revealed that higher temperatures increase moisture absorption, however detrimental to the fibre’s structural integrity. Furthermore, the interaction between RCP and bitumen emulsion disclosed that RCP does not absorb bitumen, hence maintaining the optimal bitumen content, contributing to the mixture’s cost effectiveness and sustainability.
Key findings demonstrate that incorporating 1% RCP into CMA mixtures improves fatigue resistance, while including GC filler enhances the early life strength and stiffness, especially at higher curing temperatures. Nevertheless, increasing RCP content beyond 1% negatively impacts stiffness due to increased air void contents, while higher curing temperatures can reduce flexibility. The research highlights the importance of optimising RCP content, curing conditions, and GC filler inclusion to drastically improve the mechanical and durability performance of CMA. This results in a more practical alternative to HMA, especially in regions with extreme environmental conditions.

Date of Award	May 2025
Original language	English
Awarding Institution	Aston University
Supervisor	Mujib Rahman (Supervisor) & Ahmed Abed (Supervisor)