Shruti Singh

ORCID Identifier(s)

0000-0001-7743-7671

Graduation Semester and Year

2022

Language

English

Document Type

Dissertation

Degree Name

Doctor of Philosophy in Civil Engineering

Department

Civil Engineering

First Advisor

Sahadat Md Hossain

Abstract

Plastic has many good properties such as inexpensiveness, light weightedness and durability, but it comes with one major catch i.e., its ‘indestructibility’. Plastic waste is now omnipresent and highlights that all plastic ever produced still exists in some shape or form either as macro, micro or nano plastics, making it one of the greatest challenges our planet is facing today. At the same time many existing pavements are experiencing structural and functional deficiencies due to rapid growth in traffic volume. This has led to an ever-increasing rise in construction and rehabilitation cost. So, an alternative has been explored through this research work that could provide the cost effective and environmental friendly solution to road maintenance, with the mass consumption of waste plastic. Incorporation of waste plastic in CAM has been proposed for road construction and maintenance purposes and check its viability in terms of rutting and crack resistance. An experimental program was developed to conduct different volumetric and performance tests with two different types of asphalt (PG 70-22 and PG 64-22), three different types of plastic (LDPE, HDPE and PP) and at four different trial plastic content (4%, 8%, 12% and 16%). The waste plastic were dry mixed with Crack Attenuating Mix (CAM) to evaluate plastic as potential binder in (CAM). A balanced mix design procedure has been developed to produce a new mix called “PCAM: Plastic Modified Crack Attenuating Mix” with the proposal of optimum binder (asphalt+plastic) content. Efforts has also been made to make CAM more economical by using class B aggregates instead of class A aggregates and PG 70-22 and PG 64-22 instead of PG 76-22. For being conservative a lower binder content of 6.5% instead of (7%-8%) is also proposed. Over the past decades asphalt mixes have been modified to completely eliminate the rutting which resulted in the stiffer mixes having decreased flexibility and cracking resistance, which further resulted in premature cracking of asphalt layer and has now became utmost concern for the pavement industry. Currently, TxDOT is using Texas Overlay Tester (OT) to evaluate the cracking resistance of HMAs. But this test is labor intensive and time consuming. Hamburg test is easier to perform. Hence, in order to estimate the crack resistance of plastic modified CAM, an MLR models were developed correlating the rut depth, asphalt type, plastic type and plastic content with crack propagation rate (CPR). According to the outcome of the Hamburg Test result it clearly shows that inclusion of plastic has an added advantage in improving the deformation and stripping resistance of mix design. The results from IDT and OT tests indicates that the tensile strength and toughness of the mix is increasing with the increased plastic content, indicating increased resistance during crack initiation phase. But mix resistance to crack propagation was observed to be reducing with increasing plastic content, which is reflected in decreased value of CPR and number of cycles to failure. This research work is aimed to serve dual purpose by proposing the reduction of legacy plastic waste by incorporating it into road construction and maintenance applications, which will result in the enhanced performance and extended service life of the pavement.

Keywords

Rutting, Cracking, Asphalt, Bitumen, Crack attenuating mix, Balanced mix design, Waste plastic

Disciplines

Civil and Environmental Engineering | Civil Engineering | Engineering

Comments

Degree granted by The University of Texas at Arlington

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