Laboratory Evaluation of Polymer and Multi-Grade Asphalt Binders, MLR-90-5, 1992

A number of claims have been made that polymer modified asphalt cements, multi-grade asphalt cements, and other modifications of the liquid asphalt will prevent rutting and other deterioration of asphalt mixes, thereby, extending the service life of asphalt pavements. This laboratory study evaluates regular AC-20 asphalt cement, PAC-30 polymer modified asphalt cement and AC-10-30 multi-grade asphalt cement. PAC-30 was also evaluated with 15% Gilsonite and 15% Witcurb in a 75% crushed stone - 25% sand mix. These mixtures were evaluated for all Marshall properties along with indirect tensile, resilient modulus, and creep resistance.

Development of Non-Petroleum Based Binders for Use in Flexible Pavements, TR-594, 2010

Most bituminous adhesives or binders that are used for pavement materials are derived primarily from fossil fuels. With petroleum oil reserves becoming depleted and the drive to establish a bio-based economy, there is a push to produce binders from alternative sources, particularly from biorenewable resources. However, until now, no research has studied the applicability of utilizing bio-oils as a bitumen replacement (100% replacement) in the pavement industry. The main objective of this research was to test various properties of bio-oils in order to determine the applicability of using bio-oils as binders in the pavement industry. The overall conclusions about the applicability of using bio-oils as bio-binders in the pavement industry can be summarized as follows: 1. Bio-oils cannot be used as bio-binders/pavement materials without any heat pre-treatment/upgrading procedure. 2. Current testing standards and specifications, especially Superpave procedures, should be modified to comply with the properties of bio-binders. 3. The temperature range of the viscous behavior for bio-oils may be lower than that of bitumen binders by about 30°–40° C. 4. The rheological properties of the unmodified bio-binders vary in comparison to bitumen binders, but the rheological properties of these modified bio-binders change significantly upon adding polymer modifiers. 5. The high-temperature performance grade for the developed bio-binders may not vary significantly from that of the bitumen binders, but the low-temperature performance grade may vary significantly

Asphalt Binders for Thin Maintenance Surfaces, TR-435, 2003

Asphalt is used as a binder for thin maintenance surface (TMS) applications because of two key properties, it is waterproof and it adheres relatively well to the aggregate. Since asphalt is too stiff at room temperature to apply to the road surface, it is usually applied as either a cutback asphalt or an asphalt emulsion. The asphalt emulsions can be further divided into high float emulsions, cationic emulsions or polymer-modified binders, which are emulsions with polymers added to them. These types of binders are discussed further below.

Development of Non-Petroleum-Based Binders for Use in Flexible Pavements – Phase II, TR-650, 2015

Bio-binders can be utilized as asphalt modifiers, extenders, and replacements for conventional asphalt in bituminous binders. From the rheology results of Phase I of this project, it was found that the bio-binders tested had good performance, similar to conventional asphalt, except at low temperatures. Phase II of this project addresses this shortcoming and evaluates the Superpave performance of laboratory mixes produced with the enhanced bio-binders. The main objective of this research was to develop a bio-binder capable of replacing conventional asphalt in flexible pavements by incorporating ground tire rubber (GTR) into bio-oil derived from fast pyrolysis of agriculture and forestry residues. The chemical compatibility of the new bio-binder with GTR was assessed, and the low-temperature performance of the bio-binders was enhanced by the use of GTR. The newly developed binder, which consisted of 80 percent conventional binder and 20 percent rubber-modified bio-oil (85 percent bio-oil with 15 percent GTR), was used to produce mixes at two different air void contents, 4 and 7 percent. The laboratory performance test results showed that the performance of the newly developed bio-binder mixes is as good as or better than conventional asphalt mixes for fatigue cracking, rutting resistance, moisture sensitivity, and low-temperature cracking. These results need to be validated in field projects in order to demonstrate adequate performance for this innovative and sustainable technology for flexible pavements.

A Progress Report on Treating Loess, Fine Sands and Soft Limestones with Liquid Binders, HR-20, 1954

Certain areas of Iowa abound in loess, others contain soft limestones that are readily and cheaply available, and a large portion of the state is underlaid with sand. None of these materials is considered suitable in present practices for use in all-weather road construction. The loess is too fine and too difficult to handle; the limestones are considered too soft, and some of the harder ones unsound for this use; the sands are not naturally of the desired gradation and do not lend themselves to blending into satisfactory gradations. The purpose of this project is, therefore, to study and develop means and to determine the feasibility of using these materials, loess, fine sand, and soft limestones, either separately or in combinations in conjunction with liquid binders to produce paving mixtures applicable for all-weather road construction. Also included in the project was the development of methods of processing any of these materials, if necessary, to make them suitable for the desired purpose