Aggregates used in hot-mix asphalt, hydraulic cement concrete, and unbound aggregate pavement layers influence the structural integrity and durability of pavement systems.

A Federal Highway Administration (FHWA) grant will help move a prototype system that analyzes the properties of aggregates used in pavement closer to market, making specification of paving materials that enhance roadway durability and skid-resistance more reliable.

The FHWA awarded $200,000 to Pine Instrument Co. of Grove City, Pa., to refine and test its aggregate imaging system, which combines hardware that captures digital images of aggregate samples and software that analyzes characteristics – such as shape and texture – that affect pavement quality.

The grant was one of five awarded under the agency’s Technology Partnerships Program, which encourages industry to develop technologies now at the prototype stage in partnership with transportation agencies. The goal is to test promising innovations designed to improve highway quality and safety or reduce congestion in real-world settings and help make them commercially viable.

“Through the Technology Partnerships Program, we’re working to accelerate private sector engagement in addressing the challenges of building and maintaining the nation’s highway system,” says FHWA Associate Administrator King W. Gee. “Industry innovation is essential to meeting the demands of roadway users for quality and safety.”

Boosting pavement performance

Research has shown that the characteristics of aggregates used in hot-mix asphalt, hydraulic cement concrete, and unbound aggregate pavement layers influence the structural integrity and durability of pavement systems. These also affect the skid resistance of pavement surfaces.

Key aggregate characteristics include shape, such as round, elliptical, or flat; angularity, the sharpness of the corners of the aggregate particles; and texture, the smoothness or roughness of the particle surfaces. Accurate characterization of these properties – which vary with the type and source of aggregates and processing techniques – can improve specifications for projects and, ultimately, boost pavement performance and driver safety.

Manual methods now used to measure these characteristics can be time consuming and subjective, according to Richard Meininger, FHWA research highway engineer. That can lead to inconsistencies in measurement, quality assurance, and mix design.