Alleviating Permanent Deformation and Moisture Damage in Hot Mix Asphalt Using Polypropylene Fibers

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Fazli - Karim

Abstract

The asphalt pavements in Pakistan suffer from various failures where rutting and fatigue cracking are significant. These failures may occur due to uncertainty in predicting actual traffic, material properties, poor construction methods, and poor mix design. As per existing literature, polypropylene fibers (PPF) have been extensively used in pavement engineering for many years to cope with the pavement failures. These PPF are effectively used in asphalt concrete due to the adequate adhesion between PPF, bitumen, and aggregate. Therefore, in the current study, the asphalt concrete specimens for Marshall Stability, Rut resistance, and Moisture damage, modified with PPF, ranging from 2% to 10% by weight of optimum binder content (OBC), were produced at a mixing temperature of 160 oC and tested as per ASTM D1559, ASTM D8292, and ASTM D6931 protocols, respectively. An OBC of 4.42% by weight of the Marshall specimen for the conventional mix was concluded in terms of Marshall Stability and flow. The PPF of 8%, by weight of OBC, used as per the wet method in the asphalt mixture, was concluded to be optimum in terms of Marshall Stability of 15.2 KN and flow value of 2.2 mm. The modified asphalt mixtures at PPF content of 8% leads to a least rut depth of 3.44 mm as compared to conventional specimens having rut depth of 7.35 mm, particularly due to the PPF's long-lasting integrity formed in the modified asphalt mixture at an 8% PPF content, supporting the asphalt mixture's ability to sustain repeated wheel loads. The values of TSR showed an increasing trend with the increase in PPF content from 2% to 8%, particularly due to the adequate mobility and dispersion of the PPF in the asphalt mixture and cohesion due to the optimum coating in the asphalt mixture. The TSR value of the asphalt mixture decreased at 10% PPF content as compared to conventional asphalt mixtures because of excessive rigidity or a lack of the required marginal flexibility in the asphalt mixture because of excessive PPF content. Therefore, the asphalt mixture modified with 8% PPF fibers as per wet method is recommended to be used in the construction industry to control permanent deformation and moisture damage in asphalt mixtures.

Article Details

How to Cite
Karim, F. (2024). Alleviating Permanent Deformation and Moisture Damage in Hot Mix Asphalt Using Polypropylene Fibers. Technical Journal, 29(03), 1-8. Retrieved from https://tj.uettaxila.edu.pk/index.php/technical-journal/article/view/2184
Section
CIVIL ENGINEERING