Estimating the effect of aqueous cationic latex from the class of thermal elastic plastics on the properties of bitumen emulsions

To produce cationic bitumen emulsions, bitumen is used, whose penetration is not lower than 90 mm-1. Such bitumen has a small plasticity interval, which leads to a deterioration in its heat resistance at elevated temperatures and narrows the scope of application of emulsions based on it. Based on the review of emulsion modification methods, the modification has been proposed that involves mixing the finished bitumen emulsions with aqueous cationic latex. The process of interaction between a bituminous emulsion and an aqueous cationic latex has been considered. A mechanism for the disintegration of the modified bitumen emulsion on the surface of mineral materials was proposed. The emulsifiers have been selected and the composition of the aqueous phase has been chosen based on the analysis of surface tension isotherms. The influence of the modification on the properties of bitumen emulsions was investigated. It was established that the main physicochemical characteristics of the interphase surface accept similar values for the aqueous phase and emulsions based on it. It has been proven that the introduction of aqueous cationic latex quite moderately affects the basic physical-mechanical properties of emulsions, which makes it possible not to change the main technological parameters when using them. It was established that increasing the concentration of the polymer in the emulsion has a positive effect on the physical-mechanical properties of the binder. With an increase in the concentration of the polymer to 6 % the softening temperature increases by 16 °C, elasticity is 74 %, and the holding capacity at minus 25 °C is approaching 100 %. Improving the physical-mechanical properties of residual binder as a result of emulsion modification could increase the durability of layers in a roadbed based on bitumen emulsions and expand the scope of their application in the construction and repair of motorways

Mechanism Influencing the Drying Behavior of Bitumen Emulsion

The drying process of bitumen emulsion largely dominates the strength development of emulsion-based mixtures for pavement structure, thus it can be used to judge the quality of bitumen emulsion. However, the drying behaviour of bitumen emulsions was seldom considered. The emulsion drying and film formation theory are employed to study the drying process of different bitumen emulsions with a thin layer. Results indicated the drying process of bitumen emulsion can be divided into three stages: (a) an initial high evaporation rate stage; (b) an intermediate stage with a rapidly decreasing evaporation rate; (c) a final stage with a very small evaporation rate. The boundaries among the three stages can be identified by studying the water evaporation rate. Three drying parameters, i.e., the critical volume fractions of bitumen defining the boundaries among the three stages and the maximum packing fraction of bitumen droplets, are proposed to quantitatively characterize the drying behavior of bitumen emulsion. High values of these parameters indicate a bitumen emulsion that has rapid drying behavior. Therefore, these parameters are independent of the emulsifier type, but they are highly dependent on the bitumen’s droplet size. These drying parameters increase with a decrease in bitumen droplet size. Therefore, bitumen emulsion with a smaller size distribution of bitumen droplets can have a more rapid drying behavior, which is recommended in real engineering.

Anionic Bitumen Emulsions for Waterproofing

Bitumen emulsions (BE) are widely used in road construction, for building and structure waterproofing. Storage stability is one of the main BE requirements. They should only break on contact with the surface. The sodium oleate effect as a surfactant on the stability of anionic bitumen emulsions for waterproofing purposes has been studied. Bitumen emulsions with increased storage stability have been developed. The optimal content of sodium oleate, providing a high complex of emulsion and resulting binder properties has been determined.

The Effectiveness of Using Bitumen Emulsion in the Technology of Dedusting Roads with a Transitional Type of Coating

The article considers the effectiveness of using bitumen emulsion in technologies for dedusting sections of the Vilyui A-331 federal highway. The sections allocated for the work have transitional coatings of sand and gravel (crushed stone), crushed stone sand and gravel mixtures. Their wear degree is up to 100% and they belong to dust-forming and highly dusting ones. The average traffic intensity on Vilyui A-331 highway is 937 units per day. The efficiency of technologies for dedusting coatings of transitional type has been evaluated and the prospects of using cationic bitumen emulsions for these purposes have been shown.