SUPER-STABLE CATIONIC BITUMEN EMULSIONS FOR COLD RECYCLING TECHNOLOGY OF PAVEMENT

Abstract

The article presents the results of a study on the effect of a composite binder consisting of bitumen emulsion and Portland cement on the physical and mechanical properties of materials produced by cold recycling technology. It discusses the feasibility of using super-stable cationic bitumen emulsions for mixtures produced by this method.

Super-stable cationic bitumen emulsions are defined as emulsions that exhibit high resistance to decomposition, low reactivity with the mineral components of the mixture or individual aggregates, and high storage stability.

It was found that the compressive strength at 3 days in mixtures containing bitumen emulsion (at different dosages) was lower than in mixtures without it. However, by 7 days, the strength of the mixtures with emulsion surpassed that of those containing only the mineral binder. This trend continued after 28 days of curing. Thus, the cationic emulsion delays the initial hardening of the cement but does not reduce the final strength of the samples.

Furthermore, the delayed heat of hydration can result in reduced shrinkage and improved crack resistance of the layer.

The highest compressive strength at 20°C and 50°C, along with the lowest water absorption, were observed in samples containing Portland cement and 2% bitumen emulsion with the Redicote 4875 NPF emulsifier. This is expected, as this bitumen emulsion provides superior resistance to decomposition.

In terms of bitumen emulsion dosage efficiency, all performance indicators were optimized when the emulsion content in the composite binder was at 2% by weight.

Overall, the addition of bitumen emulsion slows the hardening of Portland cement, enabling longer transportation times for the mixture when produced "at the plant," and allowing for extended timeframes for laying, profiling, and compacting operations.