HOT MIX ASPHALT WITH FLY ASHES FOR DENSE-GRADED SURFACE LAYERS OF RURAL ROADS

This paper aims to define a well-structured methodology that can be applied to perform an effectiveness evaluation of strategies in the road maintenance field by emphasizing local resources use in light of life cycle impact assessment requirements. The experimental study aims to provide a methodological structure to assess when alternative aggregates to limestone can be used in the bituminous mixtures. Properties concerning mechanical, physico-chemical and environmental compatibility features were studied carefully to check fly ash use. A comparative study was carried out on the performance of two mixtures using fly ash and limestone filler. The laboratory program consisted of two phases wherein a first phase mix design is carried out by adopting the Marshall method packaging 6 hot mix asphalt (HMA) mixtures with different bitumen contents between 4% and 5.25% by total aggregate weight at 0.25% increments. In the second phase, additional mechanical properties were investigated concerning final solution of bituminous blend designed in terms of the indirect tensile strength, water sensitivity, complex modulus and cumulative axial strain. The results show that the mixtures prepared with fly ash have better mechanical properties than the mixtures with limestone filler. Furthermore, the mixtures with fly ash also have a high environmental compatibility having recorded negative results of the environmental leaching tests.