Evaluation of Bituminous Moisture Damage of High Silica Aggregate

Abstract

Moisture damage (Stripping) in Hot Mix Asphalt (HMA) is the loss of adhesive bond between aggregate particles and bitumen due to water action. Most urban roads in Iraq have been exposed to moisture damage failure because of the high silica content in aggregate, this phenomenon led to a decrease in the service life of roads and an increase in maintenance cost. This study used two anti-stripping agents: hydrated lime and Wetfix-BE. Lime was added as a powder to the aggregate in a dosage of 2.0 % of the aggregate weight and Wetfix-BE, a liquid chemical adhesion promoter for hot and warm mix asphalt, was added to asphalt at in dosage of 0.5 % from the total weight of asphalt. The retained Marshall stability, tensile strength ratio, Texas boiling test, and static immersion test are calculated to determine the resistance to moisture damage. The results indicated that both Wetfix-BE and lime could increase Marshall retained stability, tensile strength, and resistance to moisture damage of mixtures, especially at higher condition temperatures. The bitumen modified with Wetfix-BE had better results than bitumen modified with lime for all tests at different temperatures.

Keywords

• wetfix-be
• lime
• tensile strength ratio
• boiling test
• silica