Rutting and Fatigue Properties of Cellulose Fiber-Added Stone Mastic Asphalt Concrete Mixtures

Muhammad Irfan,Sarfraz Ahmed,Yasir Ali,Shahid Iqbal,Hainian Wang

doi:10.1155/2019/5604197

Abstract

This paper investigates dynamic response, rutting resistance, and fatigue behavior of three stone mastic asphalt (SMA) concrete mixtures selected on basis of nominal maximum aggregate size (NMAS): 25 mm, 19 mm, and 12.5 mm using cellulose fiber added as 0.3% of the total weight of aggregate. Superpave gyratory specimens were fabricated and subjected to the dynamic modulus (E∗) and flow tests (flow number and flow time) using an asphalt mixture performance tester. The E∗ test results were employed to develop stress-dependent master curves for each mixture, indicating that the mixture with the NMAS of 25 mm is relatively stiffer than other tested mixtures; this mixture also exhibits excellent strength against rutting failure. In addition, fatigue parameter, which is derived from dynamic response and phase angle, is determined, and results reveal that 12.5 mm NMAS mix has relatively better resistance to fatigue than other selected mixtures. Furthermore, nonlinear regression model specifications were utilized to predict accumulated strains as a function of loading cycles. Also, a flow number model is developed that predicts the rutting behavior of mixtures, and results suggest that model predicted and observed outputs of 25 mm SMA mix are found to be very close. The results of this study help in understanding the performance and behavior of cellulose fiber-added stone mastic asphalt concrete mixtures under varying simulated temperature and stress levels, which can be used in areas where the premature failure of flexible pavements is often observed. The testing protocol employed in this study will also help in evaluating pavement performance using Mechanistic-Empirical Pavement Design Guide.

Highlights

Rutting and fatigue in flexible pavements are two of the common distresses manifested on national highways across the globe
In various parts of the world, use of stone mastic asphalt (SMA) is very common for heavily trafficked areas. e reason for such usage could be the design of SMA mixtures, in which wheel load is endured by the coarse aggregate skeleton that contributes towards resistance to rutting and rich binder that seals the voids and makes it tougher. us, the contact among stones in coarse aggregate dominates, whereas the fine and intermediate aggregate sizes assist to grip the coarser particles when the mix is spaced out
Dynamic Modulus, |E∗|. e |E∗| testing was performed in accordance with AASHTO TP 62-07 [16], which recommends that |E∗| should be evaluated at four different temperatures and six different frequencies in order to develop master curves. e results obtained from the |E∗| test suggest that, for a given loading frequency, an increase in temperature, translated into 41, 55, and 26% drop in |E∗| values on average for 25, 19, and 12.5 mm mixtures, respectively

Summary

Introduction

Rutting and fatigue in flexible pavements are two of the common distresses manifested on national highways across the globe. Various factors are associated with these distresses including overloading, high temperatures, and empirical design approach used for structural design. To this end, SMA is considered an effective solution in heavily trafficked areas because of larger single size aggregate that can be used with the increased bitumen, controlling rutting susceptibility. E reason for such usage could be the design of SMA mixtures, in which wheel load is endured by the coarse aggregate skeleton that contributes towards resistance to rutting and rich binder that seals the voids and makes it tougher. E coarse aggregate provides durability that contributes towards tremendous resistance to permanent deformation, and higher bitumen content seals the voids and makes it exceedingly resilient. To enhance the mechanical properties of SMA, modified bitumen along with suitable additives can be used; and in some situations, it can reduce or even exclude the requirement for other drainage inhibitors

Methods

Results

Conclusion