Chip seal is one of the most common and cost-effective maintenance treatment approaches to improve the life-time of pavements. Recently, the research team developed a rubberized chip seal where natural aggregate is replaced with crumb rubber obtained from recycled tires. During this study, chip seal specimens with crumb rubber and mineral aggregate were designed and constructed according to three different common methods including McLeod, Kearby, and modified Kearby.

The macrotexture of the laboratory specimens was investigated using the sand patch and image processing methods to show how each reflects on the skid resistance. The values of the mean texture depth (MTD), which is a measure for pavement macrotexture, of rubberized chip seal specimens were significantly higher than that of the conventional chip seal. The British Pendulum Tester (BPT) was found unreliable for skid resistance measurement of chip seal surface because of high macrotexture. Using a sweep test with different curing times indicated that rubberized chip seal requires more curing time compared to conventional chip seal. In addition, both conventional and rubberized chip seal were highly susceptible to raveling (chip loss) in the first six hours and after that, chip loss percentage reduced significantly.

The developed rubberized chip seal was implemented in a project in Boonville City, Missouri. Traditional equipment and procedure of chip seal implementation was successfully used for the rubberized chip seal. The project displayed severe reveling due to low ambient temperature and inappropriate season of implementation. Two new techniques were developed during the field monitoring. A modification on the BPT made it a reliable means for measuring friction of the chip seal surface. Moreover, a 3D scanning technique is proposed as a highly reliable mean capable of measuring both macrotexture and friction of the chip seal surface in a short time. This study concluded that crumb rubber can be implemented successfully and easily in the field with no need to change the current procedure. It is recommended to also increase the curing time for chip seal, regardless of aggregate type, to at least six hours to improve performance. Also, using the 3D scanning technique is highly recommended since it provides reliable and comprehensive data, which make it possible to study new aspects of chip seal texture.--Executive Summary


Civil, Architectural and Environmental Engineering


Region H- Missouri Department of Natural Resources


The authors wish to extend a very sincere thank you to the Region H of the Missouri Department of Natural Resources for providing funding for this project. Matching funding provided by Missouri Department of Transportation (MoDOT) is appreciated.

Keywords and Phrases

Rubberized Chip Seal; Field Loading; Field Implementation; Seal Coat; Chip Seal; Crumb Rubber; Macrotexture; 3D Scanning

Document Type

Technical Report

Document Version

Final Version

File Type





© 2019 Missouri University of Science and Technology, All rights reserved.

Publication Date

June 2019

Available for download on Thursday, March 17, 2022