Influence of Waste Crab Shell Powder on the Rheological Properties of Bitumen

Biomaterials make good substitutes for non-renewable products often used in the asphalt pavement industry. Including them in the asphalt mix is a good way to valorize by-products from other industries and optimize the existing technologies. This chapter focuses on the use of waste crab shells as an additive in bituminous binders for road asphalt pavement. Different concentrations were tested as well as pure chitin from crab and shrimp shells. Results show that adding powder, regardless of the origin, hardens the binder and improves its high-temperature properties, with an increase in complex shear modulus over the whole studied frequency range. An elastic behavior was spotted on the crab shell powder Black diagrams for high concentrations, with a decrease of phase angle at low complex shear moduli. The study of the separate components of crab shells (chitin and calcium carbonate) shows that chitin is responsible for this rheological property. The mineral part of the shell does not have a role in the phase angle reduction, but increases slightly the complex shear modulus.