The surface chemistry of the aggregate begins to have an important role, and emulsions must be tailored to the mineralogy of different aggregate types.
More precisely, it is the poor ability of bitumen emulsion to develop sufficient bonding in the mixture skeleton, which normally takes time and is generally caused by the poor compatibility between bitumen emulsion and aggregate (even more complex with RA aggregate due to aged bitumen). One of the main obstacles that stands against the vast usage of bitumen emulsion in cold recycling is the low early mechanical performance, such as the low bearing capacity and adhesion.
GORMAN BROTHER ASPHALT EMULSION MILL SERIES
Whereas hot mixtures rely on the viscoelastic properties of bitumen, emulsion mixtures introduce a new series of conditions that must be controlled in order to successfully produce and lay these materials. Bitumen emulsion’s main properties, including type, average drop size, size distribution, rheology, and stability, as well as its further use properties, such as adhesion on the substrate, must be tailored according to the pavement application (i.e., cold recycling, chip sealing).Ĭold mixture technology presents a new set of challenges to engineers who are traditionally used to work with hot mixes. The amphiphile molecule (surfactant) prevents droplet coalescence by decreasing the interfacial tension between bitumen and water, thereby stabilizing the system and allowing emulsification. Surfactants lower the viscosity of the system in comparison to the initial viscosity of the bitumen. According to industrial experience, the proper emulsion for road applications has a high bitumen content, which normally ranges from 60 to 70%, with a unimodal droplet size distribution and an average droplet size ranging from 5 to 15 μm. For phase compatibility, non-ionic, anionic, or cationic surfactants are added at a concentration of 1–2 weight percent of the total bitumen emulsion mass. As an emulsion, bitumen emulsion is considered as an oil in water (O/W) emulsion system with water (or soap) as the continuous phase and bitumen as the dispersed phase. As a result, the cold mix emits less ozone-depleting hydrocarbons. Furthermore, there are fewer hazards of fire and burns, and the process consumes less energy. Bitumen emulsions have a significant advantage over hot bitumen since their operations need less energy because their viscosity is lower than that of hot bitumen. Bitumen emulsions are an innovative method for liquifying bitumen by dispersing it in water. its applications are quite diverse, including cold recycling mixtures, tack coating, and surface treatment. This review paper aims to enable the ultimate potential of bitumen emulsion by further reviewing the research progress of bitumen emulsion manufacturing and discussing the literature available up to now on this topic, in the realm of bitumen emulsion manufacturing and emulsion chemistry.īitumen emulsion is becoming more popular in the pavement construction sector. Therefore, discussing some important issues in this field could be useful to offer a practical guide for bitumen emulsion manufacturers when trying to formulate a well-defined bitumen emulsion to best fit its use in pavement infrastructure rather than to simply to meet standard specifications. Some of them have technical limitations to be utilized for practical industrial application, whereas others are still not understood enough to be applied in bitumen emulsion formulation. Several pre-established formulation procedures have been presented in the literature. Consequently, obtaining the desired product is mostly based on a series of random and tedious trials because of the enormous number of tests that are carried out to meet the required properties, such as emulsion stability, viscosity, droplet size (and distribution), and bitumen emulsion chemistry. The bitumen emulsion formulation process and compositional optimization are subjected to a high number of degrees of freedom. However, there are still scientific and technical obstacles standing against its regular application. One group of those materials is produced by using bitumen emulsion. The global increase of road infrastructure and its impact on the environment requires serious attention to develop sustainable and environmentally friendly road materials.
0 kommentar(er)
