Experimental Investigation of Rubber Swelling in Bitumen

Abstract

Rubber swelling in bitumen, which is a diffusion-induced volume expansion process, plays a dominant role in the design of crumb rubber modified bitumen binders and their properties development. This study aims to investigate the kinetics of bitumen diffusion into truck tire rubber, the equilibrium swelling characteristics of rubber, and the mechanical properties of rubber before and after swelling at different high temperatures. Fourier transform infrared spectroscopy results indicate that no rubber dissolution happens during the interaction in the temperature range from 160°C to 200°C. Aliphatic compounds from bitumen preferentially diffused into rubber during the swelling process. The diffusion coefficients of bitumen into rubber were determined by the sorption test using the gravimetric method. The diffusion coefficient increases with the increase of temperature in an Arrhenius form. The volume expansion of rubber during swelling was captured by the X-ray computed tomography scan images. Rubber swells faster at the earlier stages, then the expansion rate slows down. The swelling ratio of rubber increased from 1.97 at 160°C to 3.03 at 200°C after 36 h interaction. Mechanical tests by dynamic shear rheometer reveal that swollen rubber becomes softer compared with the dry rubber and exhibits obvious viscoelastic behaviors. With the increase of temperature, the softening and viscous effect are more significant. The obtained parameters can be implemented to swelling and micromechanical models to better predict the binder properties.

Performance Evaluation of Crumb Rubber Asphalt Modified with Silicone‐Based Warm Mix Additives

“…e number of loading cycles to failure has been defined as fatigue life, more especially in the strain-controlled mode. Several researchers used the peak in the phase angle approach to evaluate the fatigue life of asphalt binders, mastics, and mixtures [52,53]. According to this approach, a point showing the maximum phase angle is a reasonable fatigue failure point, since the phase angle versus time curve shows a rapid loss of the phase angle when asphalt no longer accumulates distress.…”

The Importance of the Foreman’s Motivation in the Implementation of High-rise Building Projects in Quality Management

“…For CRM modified binders, Figure 13c shows a swollen rubber particle embedded in the bitumen matrix with a multilayer structure due to the process of sequential diffusion of bitumen into the rubber [36]. In addition, previous studies have shown that swollen rubber is softer than bitumen at the intermediate temperature of 20 C [37]. When the fatigue cracks initiated in the rigid bitumen phase start to propagate, they will meet the swollen rubber particle.…”

Aging Potential and its Impact on the Bonding Strength of Rubberized RAP Asphalt Binder

“…The CR chains physically interact with the asphalt binder by adsorbing the light components of the binder (saturates and nonpolar aromatics). As a result, the CR chains swell to be 3–5 times their original size and form the gel phase. , Therefore, the binder colloid of CRMB is a two-phase structure, a gel phase surrounded by a liquid phase. The liquid-phase binder is dominated by the heavy components (asphaltene and resin), which are left after the adsorption of light components by the CR chains .…”