Abstract
In order to quantitatively study the applicability of needle/cone penetration experiment for asphalt-rubber (AR), the dynamic model of needle/cone in penetration process was established based on the Kelvin model, and the different impacts of crumb rubber (CR) particles on needle/cone penetration depth were analyzed using Matlab. The probability of needle/cone contacting CR particles in penetration process was statistically calculated. AR binders with different CR particle sizes were observed using scanning electron microscope (SEM) and prepared for testing needle/cone penetration. The results showed that the solid-liquid two-phase feature of AR binders gradually weakened with the reduction of CR particle size. At the same viscoelastic parameters, CR particles had little impact on cone penetration depth when cone contacted CR particles. The probability of cone contacting CR particles was close to 100% in penetration process while that of needle was around 50%. The standard deviations of the needle penetration experimental results for AR binders with #20, #30, #40, #60, and #80 mesh CR were 4.0, 3.8, 2.8, 1.1, and 1.1 times of cone penetration, respectively. This study shows that the cone penetration experiment has a significant advantage in evaluating the consistency of the AR binder with coarse CR.
Highlights
Nearly 1.5 billion waste tires are discarded around the world each year and the number is still increasing sharply [1]
Obvious crumb rubber (CR) particles can be observed in AR binders with #20, #30 CR, and tiny CR particles distributing in the AR binder with #40 CR can be observed
CR particles cannot be observed in AR binders with #60, #80 CR macroscopically. e scanning electron microscope (SEM) images of AR binders with #40, #60, and #80 CR are shown in Figure 2. e silver particles are CR in picture
Summary
Nearly 1.5 billion waste tires are discarded around the world each year and the number is still increasing sharply [1]. Needle/cone penetration is an important index to evaluate the AR binder’s consistency, which represents the soft (hard) degree of the binder. Exploring the applicability of needle/cone penetration experiment for the AR binder is of great significance to improve the AR binder’s product quality and popularize its applications. Huang and Pauli et al carried out experiments using eight different AR binders, and the needle penetration experimental results were highly discrete [10]. Based on the modification mechanism of coarse/fine CR, this paper emphatically analyzed the needle/cone penetration experimental process for the AR binder with coarse CR which shows obvious solid-liquid two-phase feature macroscopically. The needle/cone penetration experiments on AR binders with different particle sizes were carried out to verify the correctness of theoretical analysis. The needle/cone penetration experiments on AR binders with different particle sizes were carried out to verify the correctness of theoretical analysis. is paper can provide theoretical support for the superiority of cone penetration to evaluate the AR binder with coarse CR
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