The Guayule Plant: A Renewable, Domestic Source of Binder Materials for Flexible Pavement Mixtures

Status

Sequential Number

Identification Number

Matching Research Agency

NCHRP - IDEA Program

Principal Investigator

Student Involvement

Steven M. Lusher, Senior Research Specialist, PhD Candidate

Project Objective

Determine the feasibility of using materials that can be extracted from the guayule plant in the design and production of flexible pavement mixtures.

Project Abstract

The guayule (pronounced 'why-YOU-lee') plant grows in arid and semi-arid regions (e.g. the southwestern U.S.) and is a source of natural rubber. It was cultivated and processed during the World War II rubber shortage and is currently being processed primarily for the manufacture of hypo-allergenic latex (e.g. medical gloves, personal hygiene products). Depending on the process, many materials can be extracted from guayule. However, there are three basic products: rubber, resin, and bagasse.

The rubber and resin (biopolymers) are of particular interest as they could prove to be renewable binder materials for flexible pavement mixtures. Limited preliminary testing showed that the resin could potentially be used as a recycling agent (viscosity modifier) when designing flexible pavement mixtures with a high percentage of reclaimed asphalt pavement (RAP), a small percentage of processed roofing shingles, and some virgin aggregate.

The concept is to design a flexible pavement mixture produced with little to no virgin petroleum-based material. Due to the rising price of crude oil, flexible pavement costs have increased significantly. In regard to the concept, the potential impact on highway construction could be lower costs. A thorough experimental program is necessary to assess the limits of the use of the guayule rubber and resin in the context of this concept. Additionally, the guayule processing industry could benefit through the opening of another market for its products. Maybe more importantly, national security could be enhanced by decreasing the dependence on foreign oil.

Anticipated Benefits

Due to the rising price of crude oil, flexible pavement costs have increased significantly. In regard to the concept, the potential impact on highway construction and/or other flexible pavement applications could “eventually” be lower costs. The term “eventually” is highlighted because in the most likely scenario of using RAP and/or shingles as the major source of binder in the mix, the replacement of petroleum-based recycling agents with guayule-based materials may not be cost effective, at first. Like any new product to be put on the market, it may take time for demand and technology to make the guayule-based materials economically attractive to potential users.

It is also possible that the guayule-based materials will perform better in FPM than petroleum-based materials. Based on the literature search, the use of guayule products in the context of the concept is new; there does not seem to be a precedent indicating potential outcomes, good or bad. The prospect of developing a new and better product, in many respects, is what makes research exciting and important.

Additionally, the guayule processing industry could benefit through the opening of another market for its products. Maybe more importantly, national security could be enhanced by decreasing the dependence on foreign oil.

Milestones

Relationship to other Research/Projects

N/A

Technology Transfer Activities

Not Applicable. This is a “concept validation” project.

Transportation Research Board Keywords

Paving Materials