Mechanistic-based comparisons of stabilised base and granular surface layers of low-volume roads

ABSTRACT

Granular surface and base layers of low-volume roads (LVRs) are frequently subjected to severe damage that adversely affects safety and requires regular repair and maintenance. Various stabilisation methods have been evaluated for mitigating damage and improving serviceability of LVR systems. However, few well-documented comparisons exist of the field mechanical performance, durability and construction costs of different stabilisation methods under the same set of geological, climate, and traffic conditions. Therefore, the present study was conducted to identify the most effective and economical among several stabilisation methods for repairing or reconstructing granular surface and base layers of LVRs. In this study, a range of promising technologies from a comprehensive literature review was selected and examined using field demonstration sections. A total of nine geomaterials, three chemical stabilisers, and three types of geosynthetics were used to construct various test sections over a 3.22 km stretch of granular-surfaced road. Extensive falling weight deflectometer (FWD) and dynamic cone penetrometer tests were performed to evaluate the multilayered elastic moduli and strengths of the various sections. This paper details the design and construction of each test section, compares the as-constructed mechanistic performance of all test sections, and assesses stiffness changes of several sections one year after construction. To provide a statistical basis for the comparisons, a pairwise multiple-comparison procedure applied for unequal sample sizes and variances and the paired t-test were used to analyse the FWD test results, demonstrating that the performance measures of the various sections were significantly different.

KEYWORDS:

• Low-volume roads
• granular surface
• base stabilisation
• mechanical stabilisation
• chemical stabilisation
• geosynthetics
• recycled Portland cement concrete
• falling weight deflectometer
• dynamic cone penetrometer
• statistical analysis

Acknowledgements

The authors would like to thank the Iowa Department of Transportation for sponsoring this project. The cooperation and assistance of the Hamilton County Secondary Roads Department is greatly appreciated. The authors would also like to acknowledge the support of Hamilton County Engineer Dan Waid for overseeing construction of the test sections and providing cost records. The assistance of Greene County Engineer Wade Weiss is also appreciated in providing equipment and personnel for installation of the aggregate columns.

Additional information

Funding

This work was supported by the Iowa Department of Transportation [Project Number TR-664]. Any opinions, findings, and conclusions or recommendations expressed in this paper are those of the authors and do not necessarily reflect the views of the Iowa Department of Transportation.