With the help of FHWA’s grant, Pine Instrument is now turning the prototype into a user-friendly, industry-ready product. In phase one of the project, the company is converting the collection of components that make up the research prototype to an integrated hardware system. It also is enhancing the analysis software to make results easier for AIMS users to interpret.

The combined hardware/software system will undergo a standard ruggedness study at Texas A&M University, a partner in the project, to determine how a variety of variables impact results, says Roger Pyle, Pine Instrument’s director of product technology.

The project’s second phase will involve tests at university, commercial, and highway agency laboratories to establish the repeatability and reproducibility of AIMS results in a multi-laboratory environment. Texas A&M will analyze the data from those tests.

“It’s important to have an understanding of how reproducible the output from the system is,” Pyle says. “We want to determine how closely the results will match when one aggregate supplier evaluates a product with one AIMS system and another lab uses a different system.”

The planned outcome is an industry tool capable of accurately and rapidly measuring aggregate shape characteristics. Such a tool would offer an automated method of qualifying aggregate shape properties and surface texture to meet specifications, ensure good pavement performance, and enhance roadway safety. The ultimate goal of this whole process is to develop a commercially available product.

A future look

In addition to AIMS, research is under way on other methods for measuring aggregate characteristics. One uses X-ray tomography, an imaging method widely used for medical applications, to obtain detailed, three-dimensional information on aggregates. Both the National Institute of Standards and Technology’s Virtual Cement and Concrete Testing Laboratory and FHWA’s Turner-Fairbank Highway Research Center are conducting studies using this method.

Another method uses high-resolution laser detection and ranging (LADAR) technology to provide three-dimensional measurements of aggregates from which quantitative characteristics can be calculated. LADAR consists of a photon source, a photon detection system, a timing circuit, and optics for the source and receiver. An NCHRP project is developing a LADAR system capable of precisely measuring aggregate characteristics such as shape, volume, angularity, and surface texture.

Eventually, research efforts to better characterize aggregate properties may lead to more precise specifications for aggregate use on highway construction projects and better quality control tools for aggregate producers. “Once we have good aggregate measures that people can have confidence in, we can come up with more classes of materials and be more specific about what’s needed for a particular application,” Meininger says.