Fundamental and rheological properties of oil palm fruit ash modified bitumen

This study was conducted to investigate the suitability of using oil palm fruit ash (OPFA) as a bitumen modifier. The OPFA was used to fulfil all bitumen modification requirements, as well as to take advantage of a waste by-product of the palm oil mill industry which could help to reduce environmental pollution. Twenty-four OPFA-modified bitumens (OPFA-MBs) were produced by the laboratory mixing of normal bitumen (80/100) from two sources with Fine and Coarse OPFAs of six different contents. This process was conducted at a mixing temperature of 160 °C, a mixing time of 60 min and a mixing stirring speed of 800 rpm. The consistency and rheological characteristics of the OPFA-MBs were analysed by means of conventional as well as dynamic mechanical analysis using dynamic shear rheometer (DSR), bending beam rheometer (BBR) and direct tension test (DTT). The results of the investigation indicate that binder compounded with OPFA becomes less susceptible to temperature, improve resistance to rutting at 70 °C, fatigue cracking at 20 °C, and thermal cracking at −17 °C of the surface pavement temperature compared to the unmodified bitumen. The OPFA-MB can be categorised as a binder with penetration grade of 60/70 or as PG 70–16 in the performance based system. Finally, it can be deduced that it is feasible to use OPFA as a modifier of bitumen.