Factors influencing the strength of foamed bitumen stabilised mix

Abstract

Recycling of asphalt pavements has increased significantly since 1970 and in Malaysia the use of foamed bitumen as stabilizing agent was first introduced in year 2001. Recycling of asphalt pavements involves mixing of existing pavement material with stabilizing agent such as foamed bitumen, bitumen emulsion, cement or lime and placed on the milled pavement and compacted. Although the asphalt pavements recycling with foamed bitumen as stabilizing agent is gaining recognition and acceptance as a cost effective method of rehabilitating distressed pavement, so far in Malaysia no study has been carried out on the characteristic of foamed bitumen stabilized mix. The strength of foamed bitumen stabilized mix is influenced by factors such as cement content, moisture level and curing time. This study evaluates the effect of ordinary Portland cement as active filler, curing time and moisture content on the strength properties of foamed bitumen stabilized mix. Foamed bitumen treated samples with different RAP proportions were tested for their strength properties at various active filler contents, curing time and moisture contents. It was found that the strength in terms of resilient modulus, Unconfined Compressive Strength (UCS) and Indirect Tensile Strength (ITS) values, increased with curing time and percentage of active filler. It was also found that the maximum strength in terms of resilient modulus, Unconfined Compressive Strength (UCS) and Indirect Tensile Strength (ITS) was not at Optimum Moisture Content (OMC) and the strength decreased as the RAP proportion increased.