Effect of Gilsonite Use on Storage Stability of Styrene-butadiene-styrene Modified Bitumen

Abstract

Styrene-butadiene-styrene (SBS) polymer is one of the most preferred additives to improve performance in hot mix asphalt pavements. The storage instability, in other words, the separation of a polymer-rich phase from the bitumen-rich phase in the course of storage and transportation is one of the prevalent problems in SBS modified bitumen. The present study attempted to obtain modified bitumen at the same performance level with the SBS modified bitumen, but stable with respect to the storage stability. For this purpose, both SBS and American Gilsonite (AG) were used in modified bitumen production. It was determined that modified bitumen at the same performance level was obtained with the use of 5 % SBS or 18 % AG in bitumen modification. It was also determined that the performance levels of the modified bitumen obtained with the use of 2 % SBS + 13 % AG, 3 % SBS + 10 % AG and 4 % SBS + 6 % AG were similar. Additionally, 2 %, 3 % and 4 % SBS modified bitumen were used for the assessment of storage stability properties of the SBS modified binders. These 8 different modified bitumen samples were tested for storage stability based on the EN 13399 standard. Penetration, softening point, rotational viscometer, bending beam rheometer, and dynamic shear rheometer tests were conducted on the samples. Based on all conducted tests, it was determined that more stable binders were obtained with the use of AG and SBS in terms of storage stability compared to solely SBS modified bitumen.

A Review on Improving Asphalt Pavement Service Life Using Gilsonite-Modified Bitumen

“…Yalçın et al [41] carried out experimental work to investigate the effect of using gilsonite on the storage stability of SBS-modified asphalt binder. The results of penetration tests indicated that the most stable modified binders based on storage stability were 18% gilsonite and 2% SBS + 13% gilsonite.…”

“…Other tests used in assessing the performance of the gilsonite-modified binder at high temperatures and at low temperatures were DSR and BBR, respectively. Based on the available literature, the gilsonite improved the performance of asphalt binder in high temperatures through increased shear strength of the modified binder [12,15,17,28,37,39,41]. However, the reviewed studies confirmed the weakness of gilsonite as a modifier for asphalt binder in terms of its properties at low temperature, due to the stiffness values of gilsonite-modified asphalts increasing with increasing gilsonite concentration [15,38,39].…”

“…Since gilsonite is recognized as an additive material which contributes towards to modification of the asphalt binder and consequently improves the asphalt mixture properties, some of the research projects [37][38][39]41,42] have carried out further investigations combining other additives alongside gilsonite to develop the asphalt binder. Most of these investigations have decided to select SBS as an extra additive with gilsonite, due to SBS improving the HMA performance properties, and also used gilsonite to replace SBS due to SBS being an expensive additive [37,38,41]. Based on the rheological evaluation of the modified binders, using gilsonite with SBS in the same mixture decrease the viscosity of binder [37,38], which helps to increase the workability of the asphalt mixture by decreasing the mixing and compaction temperatures.…”

“…Based on the rheological evaluation of the modified binders, using gilsonite with SBS in the same mixture decrease the viscosity of binder [37,38], which helps to increase the workability of the asphalt mixture by decreasing the mixing and compaction temperatures. Based on the reviewed studies, modification of the asphalt binder with gilsonite and SBS improved stability, ITS, moisture sensitivity and fatigue life [37,38,41]. It also improved the storage stability of asphalt-modified binder [41], thus, extending the service lives of HMA.…”

“…Based on the reviewed studies, modification of the asphalt binder with gilsonite and SBS improved stability, ITS, moisture sensitivity and fatigue life [37,38,41]. It also improved the storage stability of asphalt-modified binder [41], thus, extending the service lives of HMA.…”