Bitumen Extraction Techniques and their Influence on Hot Mix Asphalt Properties

The bitumen content plays a crucial role in ensuring the quality of hot mix asphalt (HMA). Precise measurement of bitumen levels in HMA is vital for assessing its performance and durability in pavement applications. This study employs two systematic methods for determining bitumen content using the volumetric properties of aggregates, asphalt in the HMA. The methods used are the Centrifuge Solvent Extraction Test (AASHTO T164), which quantitatively extracts bitumen from bituminous paving mixtures, and the Ignition Furnace Test (AASHTO T308), which measures the bitumen content in bituminous mixtures. Laboratory data were collected from two mixes of asphalt concrete wearing course (14 mm and 20 mm). Designed with the Marshall mix design system according to the AASHTO standard. Aggregate from a quarry at Ras Al-lafia and bitumen of 60/70 PEN. The optimum bitumen content for each mix was 5.0% and 5.3%, respectively. Samples were extracted using the centrifuge method at a speed of 3600 rpm and the ignition method at a temperature of 538°C. Testing revealed a significant difference in bitumen content between the two methods. Additionally, sieve analysis results showed that high temperature and solvent exposure affect aggregate gradation, leading to noticeable differences.