Date of Award

2026-05-01

Degree Name

Doctor of Philosophy

Department

Civil Engineering

Advisor(s)

Imad Abdallah

Abstract

Field sands are commonly incorporated into hot mix asphalt (HMA) pavements due to their availability and cost-effectiveness compared to crushed aggregates, primarily to enhance workability. Their usage, however, is generally restricted to no more than 10% of the total aggregate content because of concerns regarding their potential negative influence on pavement performance. A major concern is the presence of deleterious clay particles, which can substantially affect the behavior of asphalt concrete (AC). This research explored how clay minerals influence AC performance by examining Superpave mixtures and characterizing both clay and sand properties. The methylene blue value (MBV) was employed to evaluate clay characteristics, while the sand equivalent (SE) test was used to assess sand quality. Rutting and moisture-induced damage resistance were measured using the Hamburg wheel tracking test (HWTT). The experimental program utilized Superpave gradation C, twenty-four different field sand sources, two asphalt binder grades (PG 64-22 and PG 70-22), and hydrated lime as an anti-stripping additive. Among the field sands tested, MBV ranged from a low of 3.7 mg/g to a high of 45.8 mg/g. When measured on the aggregate blend, the MBV varied between 2.4 mg/g and 10 mg/g. SE values for the field sands fell between 37 and 98, whereas the aggregate blends used in the mixtures exhibited SE values ranging from 50 to 91. For mixtures prepared with PG 64-22 binder, an MBV below 4 mg/g on the aggregate blend corresponded to excellent performance, while mixtures using PG 70-22 binder showed optimal behavior at MBV levels below 8 mg/g. These trends remained consistent across the three field sand contents examined i.e., 5%, 10%, and 20% by total aggregate weight. Additionally, the findings demonstrated that employing a stiffer binder grade and incorporating hydrated lime enhanced the moisture damage resistance of HMA mixtures containing field sands. Based on these results, updated guidelines are proposed for successfully integrating field sands into Superpave mixtures while maintaining satisfactory pavement performance.

Language

en

Provenance

Received from ProQuest

File Size

118 p.

File Format

application/pdf

Rights Holder

Suhail Rashid Vaid

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