How the Mix Factors Affect the Dynamic Modulus of Hot-Mix Asphalt

• Main Authors: Md Rashadul Islam, Sylvester A. Kalevela, Guy Mendel
• Format: Article
• Language: English
• Published: MDPI AG 2019-07-01
• Series: Journal of Composites Science
• Subjects: hot-mix asphalt; dynamic modulus; effective binder content; air void; voids-in-mineral aggregates; voids-filled-with asphalt
• Online Access: https://www.mdpi.com/2504-477X/3/3/72

Hot-mix asphalt (HMA) is a composite material consisting of stone-aggregates, sand, asphalt binder and additives. The properties of this combined material are dependent on the volumetric parameters used in the mix design. This study investigates the effects of volumetric mix factors on the dynamic moduli (<i>E*</i>) of eleven categories of HMAs. For each category of asphalt mixture, the variations in dynamic modulus for different contractors, binder types, effective binder content (<i>V_be</i>), air void (<i>V_a</i>), voids-in-mineral aggregates (VMA), voids-filled-with asphalt (VFA) and asphalt content (AC) are assessed statistically. Results show that the S(100) mixture (nominal size of 19 mm, 100 gyrations) with the Performance Grade (PG) binder of PG 64-22 has the highest value of <i>E*</i> at low temperature or high reduced frequency. At high temperature or lower reduced frequency, S(100) PG 76-28 has the highest <i>E*</i> value. The SX(75) mixture (nominal size of 12.5 mm, 75 gyrations) with the binder of PG 64-28 has the lowest <i>E*</i> value at high temperature or lower reduced frequency. At low temperature or high reduced frequency, SX(75) PG 58-34 has the lowest <i>E*</i> value. The Stone Mix Asphalt (SMA) mix has a lower <i>E*</i> compared to S(100) and SX(100) mixes ((nominal size of 12.5 mm, 100 gyrations) with the Performance Grade (PG) binder of) at low temperature. The <i>E*</i> increases with an increase in <i>V_be</i>, <i>V_a</i>, and VFA, and decreases with an increase in VMA and AC. The <i>E*</i> of a mix can vary from 200 ksi (1380 MPa) to about 1000 ksi (6900 MPa) for a particular frequency (10 Hz) and temperature (21.1 &#176;C), even if samples are from the same contractor.