The use of lignin for sustainable asphalt pavements: A literature review

Nowadays, one of the most interests of modern society is to replace increasingly larger quantities of petroleum -derived products, which is a non-renewable source progressively depleting, so promoting both environmental and economic benefits. In this context, the practice to employ renewable sources to replace part of the bitu-minous materials is an effective approach in pavement engineering. Among different biomasses which are recognized as possible sources mixable with bitumen, lignin can represent a valid material. Lignin is a natural resource commonly deriving from the by-product of the production of pulp and paper industry. It is the second most common biopolymer on Earth and represents a potentially attractive alternative as partial substitute of bitumen. However, in order to understand the environmental and technical feasibility of the application of lignin in bituminous pavement applications, a multi-scale approach must be adopted. For this purpose, the paper aims at providing an overview of the use of lignin as renewable source in bituminous binders and mixtures, by investigating chemical, rheological and mechanical properties of lignin modified asphalt materials. Moreover, based on the available literature, field application experiences and Life Cycle Assessment (LCA) analysis are also discussed.