Evaluation of compactability and mechanical properties of bituminous mixes with warm additives

Among the different existing asphalt technologies used to manufacture mixes at low temperature, this article focuses on the use of different additives, both chemical and organic, and on the use of zeolites to foam the bitumen. The influence of manufacture and compaction temperatures has been analyzed for seven different mixes in relation to compaction by gyratory compactor and also to mechanical properties, such as water susceptibility and stiffness modulus. The results have shown that when the temperature is reduced, mixtures with additives require less compaction energy and their water susceptibility improves compared to the Reference mix at the three temperatures studied. Moreover, the stiffness modulus is affected by working temperatures, although this variation was smaller in the mixes manufactured with additives.

Research highlights
► Measuring of compaction energy: use of CEI-TDI indexes.
► Use of additives: lower CEI values at lower working temperatures than R mix at 160 °C.
► Use of additives: similar TDI values at lower working temperatures than R mix at 160 °C.
► Reduction of working temperature: mixes less stiff, with worse behavior in %ITSR.
► Addition of additives improved %ITSR and reduced stiffness modulus compared to R mix.