The development of polyurethane modified bitumen emulsions for cold mix applications

Abstract

Bitumen emulsions stand for an alternative paving practice to the traditional hot-mix asphalts. In addition, modified bitumen emulsions show a better performance than unmodified ones. This work studies the feasibility of obtaining polyurethane modified bitumen emulsions, in which an isocyanate-functionalized polyol constitutes the bitumen modifier (in varying concentration from 1 to 4 wt.%). Storage stability and high in-service performance are evaluated by means of evolution of droplet size distribution (DSD) and rheology tests, respectively. Regarding the emulsion stability, the key factor seems to be the bitumen modifier concentration used to prepare the modified emulsions. Thus, for a selected 50 wt.% bitumen fraction, there is a limit concentration (between 1 and 2 wt.%) above which the emulsion becomes unstable under storage. Hence, this result limits the modifier content that can be used in the emulsion and the final level of modification achieved if compared to the original nonmodified emulsion. On the other hand, the rheological characterization conducted on the emulsion residues at 60ºC has shown an improved resistance to deformation.In terms of applicability, polyurethane modified bitumens allows for the obtaining of modified emulsions which can be prepared at much lower temperatures than those derived from other polymers.

Saving Energy in the Transportation Sector: An Analysis of Modified Bitumen Application Based on Marshall Test

“…However, in this study, the used polymers were completely manufactured and developed at a local level. In addition, back in 2015, studies [32][33][34] analyzing the efficient use of polyurethane-foam-modified bitumen [35] proposed a completely new approach of developing in situ polymerization of monomers that was derived from PET wastes. In these studies, the materials were replaced by up to 10%.…”

“…Three samples were prepared for each of the different percentage of additives added to bitumen. The average stability value of all three samples for each tested proportion was considered for detailed analysis with reference to previously followed procedures [2,10,15,25,34,62,63], as shown in Table 5. The testing of the modified bitumen samples showed that stability and flow value, along with mixing temperatures, were within ranges of up to 40% modification, i.e., PUF 5 and PW 5.…”

Formulation of Emulsified Modification Bitumen from Industrial Wastes

“…Besides, bitumen emulsion presents a much lower viscosity and can be applied at a temperature as low as 80 °C. A conventional binder is sprayed at 160-200 °C so there is a much more additional risk of fire and explosion [9]. Since the beginning of the evolution in recycling technology, many studies involving EMB formulations and applications have been conducted and published.…”

“…However, not much waste was used and limited in terms of its application. Carrera et al [9] stated that using recycled polyethylene by up to 5 wt.% improved the bitumen performance at high service temperatures of 60 °C. Carrera et al [10] claimed that a higher content of polymer of 4 wt.% enhanced the resistance to permanent deformation at approximately 60 °C compared with the standard nonmodified bituminous emulsions.…”

Modification of bitumen emulsion via heterocoagulation with SIS triblock copolymer latex

“…Bitumen, a byproduct of crude oil distillation, has been largely used as a binder of mineral aggregates in road paving . The common pavement technique, hot spray chip sealing, requires the bitumen to be applied at a temperature of typically 180 °C, which leads to significant consumption of energy and high levels of carcinogen emissions to the environment during road construction and maintenance operations, which increases risks to the health of the operators . Growing concerns about energy conservation and environmental protection have led to an interest in the production of bitumen emulsions for a number of years.…”