Estimating In Situ Optimum Bitumen Content of Dense Bituminous Macadam: An Alternative Approach

摘要

Optimum bitumen content (OBC) in dense bituminous macadam (DBM) in India is determined using Marshall mix design method, which simulates the field condition in laboratory. It is a cumbersome, temperature-controlled laboratory process varies widely from the actual field condition. To overcome this mismatch, an easy empirical method is attempted for calculating in situ OBC in DBM. In the process, the OBC is calculated as a function of physical properties of the materials used in DBM for bitumen viscosity grade-30 (VG-30) and compared with the actual bitumen consumptions in the field samples obtained through bitumen extraction test. The laboratory DBM specimens prepared based on each field sample gradation using OBC calculated by empirical method are tested for Marshall properties for field acceptability. The analysis of forty-field samples concluded that the OBC calculated by empirical method can be comparable with actual consumption with a negligible average variation of 0.03554%, ascertaining the use of alternative method as an in situ model of calculating OBC for DBM.