Improving the storage stability and workability GTR-modified binder and mixtures with Sasobit and sulfur

Description

Improving the storage stability and workability GTR-modified binder and mixtures with Sasobit and sulfur

Amirhossein Ghasemirad, Seyed Mohammad Asgharzadeh and Nader Tabatabaee

ABSTRACT. A noticeable increase in the viscosity of a binder because of the absorption of aromatics is a common side effect of modifying a binder with additives. Some modifiers may separate from the binder phase during storage and accumulate at either the top or bottom of the container. Both alternatives mean poor storage stability at high temperatures. Binder modified with crumb rubber, or ground tire rubber (GTR), performs better than neat binder on most performance criteria, but is not exempt from these problems. Experience has shown that warm mix asphalt additives can effectively reduce binder viscosity. Furthermore, the sulfur-sulfur and sulfur-carbon crosslinks induced by the introduction of sulfur improves the storage stability of GTR-modified binders. The current study was undertaken to address the viscosity and storage stability problems of crumb rubber modified binder using Sasobit, a common WMA additive, and sulfur. The cigarette tube test for modified binders was employed to evaluate storage stability and an asphalt mixture workability test was used to determine the workability of the modified binders and mixtures. The results demonstrated that the addition of Sasobit and sulfur to GTR-modified binder effectively improved the viscosity, workability and storage stability of the binder.

KEYWORDS: crumb rubber, modified binder, sulfur, crosslinking, Sasobit, storage stability, viscosity