Fundamental characterization of SBS‐modified asphalt mixed with sulfur

Abstract

The purpose of this study was to characterize the mechanical behavior of asphalt modified by styrene–butadiene–styrene (SBS) and sulfur. Viscosity, microscopy, and rheological tests were conducted to understand the engineering properties of the polymer‐modified asphalt (PMA). Without the addition of sulfur, the polymer‐modified asphalt was microheterogeneous and was made up of two distinct finely interlocked phases, especially at high SBS concentrations. After the addition of sulfur, the PMA was observed to have smaller asphalt domains and a fairly homogeneous dispersion of the asphalt in the SBS matrix. The compatibility between polymer and asphalt produced an elastic network into the asphalt. The addition of sulfur resulted in an excellent elastic system and substantially increased the rheological properties of the PMA. Because of the colloidal nature of asphalt cements, their engineering properties were greatly improved because of the reinforcement of the SBS polymer and the physical‐chemical interaction between SBS and asphalt. The difference in the softening point between the top and bottom layers decreased significantly, and elastic recovery increased when was sulfur was present. A viscoelastic model was examined and shown to be appropriate for predicting the rheological properties ofthe asphalt–SBS blend mixed with sulfur. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 2817–2825, 2007

Polymer modification of bitumen: Advances and challenges

“…Researchers have attempted different ways to remove these drawbacks, including sulfur vulcanization [82][83][84][85][86][87], adding antioxidants [22,88,89], using hydrophobic clay minerals [90][91][92][93][94][95][96][97][98] and functionalization (including application of reactive polymers) [10,[99][100][101][102][103][104][105][106][107][108][109][110][111][112][113]. Including saturation [2,12,138], which has been discussed above, some attempted measurements for removing PMB's drawbacks are listed in Table 2 with their advantages and disadvantages.…”

“…SBS modified bitumen) [82][83][84][85][86][87]. It is believed that sulfur works in two ways: chemically crosslinking the polymer molecules and chemically coupling polymer and bitumen through sulfide and/or polysulfide bonds [83].…”

“…It was proven that sulfur vulcanization led to some improved properties of some PMBs. Besides enhanced storage stability, some researchers [83][84][85]148] claimed that sulfur vulcanization could also improve the elasticity, deformation resistance and some rheological properties of the PMB, but other ones [86,87] found that sulfur vulcanization made the PMB more susceptible to oxidative ageing and dynamic shear and concluded that it is not a good idea to use sulfur as a sole additional modifier in PMB. Furthermore, hydrogen sulfide, a hazardous gas for both human health and the environment, could be generated during sulfur vulcanization because of the abstraction of hydrogen atoms in both bitumen and polymer modifiers, especially at high temperatures [149][150][151].…”

Upgrading Iranian petroleum sludge using polymers

“…Increasing the sulfur content by 30-50% in bitumen causes the bitumen to have significantly increased resistance. Among a variety of polymers, styrene-butadienestyrene (SBS) is mostly used in modified asphalt (Chen and Huang 2007). Adding from 3 to 6% of the polymer significantly improves the flexibility, resistance and temperature sensitivity of asphalt (Chen and Huang 2007).…”

“…Among a variety of polymers, styrene-butadienestyrene (SBS) is mostly used in modified asphalt (Chen and Huang 2007). Adding from 3 to 6% of the polymer significantly improves the flexibility, resistance and temperature sensitivity of asphalt (Chen and Huang 2007). The viscosity of bitumen solutions in heptol and heptane above the level causing the onset of asphaltene precipitation has been studied by Mozaffari et al 2015).…”