Multiple Stress Creep and Recovery Behavior of SBR-Modified Bitumen Emulsions

The effect of two grades of styrene-butadiene rubber (SBR) at 2, 4, 6, and 8 wt. % on the deformation behavior of cationic polymer-modified bitumen emulsion by a multiple stress creep and recovery test at three different temperatures (58 degrees C, 68 degrees C, and 78 degrees C) was investigated. It was observed that increasing SBR latex content leads to a decrease in nonrecoverable creep compliance (J(nr)) of the bituminous residue, whereas increasing temperature leads to an increase in J(nr). The results also revealed that reduction in J(nr )is not remarkable for polymer content higher than 6 wt. %. Furthermore, comparing the effect of different SBR5 revealed that at equal polymer content, the J(nr )of SBR-modified bitumen emulsion residue was found to be twice that of a branched carboxylated styrene-butadiene rubber (X-SBR)-modified one. At the same polymer modification rate and temperature, X-SBR can be used for higher traffic levels compared to an SBR-modified bitumen emulsion.