There are millions of kilometers of unpaved roads around the world managed by
numerous authorities, land owners, and public and private organizations. Common
to all of these roads are unacceptable levels of dust, poor riding
quality (caused by erosion, washboarding, and/or raveling), and/or impassability
in wet weather, and expensive maintenance and gravel replacement activities. Along
with good construction practices, these problems can often be mitigated through
better gravel selection, or by blending two or more materials to meet a
performance-based specification.
With the growing interest in converting severely distressed low-volume paved roads to
engineered unpaved roads, understanding expected performance in terms of the material
properties after the conversion, which typically involves pulverizing the
existing surface and blending it with the underlying layers, is increasingly
important to ensure that the unpaved road is “better” than the paved road
was. Mechanical stabilization of unpaved roads through blending of two
materials is not new. However, determining appropriate blending ratios
to meet performance-based specifications tends to be done on a trial
and error basis until a satisfactory blend is achieved. This tool aims to
eliminate the trial and error nature of material blending by providing a
more accurate starting blend that can then be refined to provide optimal
performance for a given application.
An overview of performance-based specifications for unpaved road materials can be
downloaded
here. Use of this tool is fully described in the UCPRC guidelines
entitled
Guidance on the Conversion of Severely Distressed Paved Roads to
Engineered Unpaved Roads and
Guidance on Performance-Based Material
Selection and Blending for Unpaved Roads.
Disclaimer
This Unpaved Road Material Design Tool has been developed to guide selection and/or blending
of materials to meet a performance-based specification. Using the tool requires input of
laboratory test results for the actual materials that will be used. Skipping the laboratory
testing and guessing input values, or using default values from other projects, will lead to
inaccurate output values. Output from the tool provides a starting point for a blend, which
will need to be tested to confirm that it meets the required specification. In no event shall
the University of California be liable to any party for direct, indirect, special, incidental, or
consequential damages, including lost profits, arising out of the use of this system, even if
the University of California has been advised of the possibility of such damage. The University
of California specifically disclaims any warranties, including, but not limited to, the
implied warranties of merchantability, fitness for a particular purpose and noninfringement.