Bitumen Foaming Optimisation Process on the Basis of Rheological Properties.

Marek Iwański,Przemysław Buczyński,Grzegorz Mazurek

doi:10.3390/ma11101854

Abstract

This article discusses the results of bitumen foam properties optimisation with respect to three factors: air pressure, bitumen temperature and amount of water. The test materials were unmodified bitumen 50/70 and bitumen 50/70 modified with 2.5% synthetic wax. The experiment was designed according to the 3(3−1) fractional factorial design. The distribution of parameters of bitumen foam were measured with the authors’ original apparatus using a laser beam. This measurement method increased the accuracy of maximum expansion ratio (ER) and half-life (HL) estimation. Based on HL and ER results, it was found that the foaming process increased bitumen stiffness due to the dynamic ageing of the bitumen. The experimental design allows more effective control over the properties of foamed bitumen with respect to its intended use. The presence of synthetic wax extended the half-life of the bitumen foam.

Highlights

One of the important factors for obtaining durable bituminous mixtures is the use of bitumen with a viscosity that will provide the mix with high in-service resistance to permanent deformation that correlates with high stiffness modulus and with adequate workability in the manufacturing process [1,2]
Analysis of the results (Figure 4a,b) shows that, at the 2.5% water content, expansion ratio (ER) was similar for both bitumen types
Results of of Analysis the resultsParameters (Figure 4a,b) shows that, at the 2.5% water content, ER was similar for both bitumen types

Summary

Introduction

One of the important factors for obtaining durable bituminous mixtures is the use of bitumen with a viscosity that will provide the mix with high in-service resistance to permanent deformation that correlates with high stiffness modulus and with adequate workability in the manufacturing process [1,2]. Research results reported in [7,8] indicate that foam expansion and its stability are dependent on the proportion of water used in the foaming process. It affects the size and distribution of the foam bubbles, thereby the shape of the foam decay curve [9] and the foaming index (FI) need to be determined [7]. Viscosity can be reduced with the application of zeolites [11] or of synthetic waxes that improve foaming parameters by stabilising foam decay [12], as does increasing the asphaltene fractions [13]. Chemical foam-enhancing agents are used to improve foam stability [9]

Objectives

Methods

Results

Conclusion