Laboratory Study on Moisture Susceptibility of Dense Graded Mixes

摘要

Moisture damage is the degradation of the mechanical properties of the material attributable to the presence of moisture in its microstructure. To enhance the life of bituminous pavements, it is necessary to understand moisture's damage on pavements and to evaluate the effects of hydrated lime as moisture damage resisting agents. The basis of laboratory work was AASHTO T 283 test and it was performed on two types of dense graded bituminous mixes that included dense bituminous macadam and bituminous concrete mix. The study was carried out for mixes prepared without lime, and the same process was repeated with addition of 2% quantity of hydrated lime. The addition of hydrated lime in the asphalt mix improves the tensile strength ratio. However, a well-controlled lime treatment is required to maximize distribution and dispersion of lime particles on aggregate surfaces. This study also presents various causes of moisture damage and their mechanisms. Attention is also given to the chemical and mineralogical composition of aggregates and effect of some important minerals on moisture susceptibility of aggregates.