ARR-MAZ Products Background

Moisture damage or stripping is an asphalt pavement distress that is generally recognized as the loss of the bond between the asphalt binder and the aggregate. Several pavement distresses that can include stripping as the underlying cause are rutting, cracking, raveling, flushing, and bleeding. Stripping can progress from either the top or bottom of hot mix pavement layer. The common cause in all cases of stripping is the presence of water. The potential for a hot mix asphalt pavement to incur moisture damage can be controlled or reduced through material selection, mixture designs that include a high asphalt film thickness, additives, proper pavement design, construction, compaction, and drainage. Many agencies include moisture sensitivity testing in the asphalt mixture design stage. The outcome of this testing can be used to eliminate certain asphalt and aggregate combinations or to require the use of an antistrip additive. The most commonly used antistrip additives are hydrated lime and liquid chemical additives. The moisture sensitivity test procedure recommended in the SHRP SuperPave mixture design protocol is AASHTO T-283, “Resistance of Compacted Bituminous Mixture to Moisture Induced Damage”. The purpose of this research is to determine if hydrated lime and high performance chemical additives perform similarly using AASHTO T-283 as the prediction model for the moisture sensitivity of a hot mix asphalt mixture. In this research, the optional freeze cycle was incorporated in the test method in order to increase the potential for moisture damage to occur to the specimens. This was done to distinguish high performing, no additive mixtures and also at the recommendation of McGennis and Aschenbrener that high traffic and severity one pavement mix designs should include it (1). An additional purpose of this research was to determine the effective dosage concentrations for the liquid chemical additives