Implementation and experimental monitoring of a subgrade road layer based on treated marine sediments

摘要

Abstract Purpose In France, 50?mm3 of sediments are dredged every year in ports and rivers for the development and maintenance of waterways. The aim of this research was to determine the feasibility of using sediment as a material for subgrade road layer. This required preliminary work in the laboratory in order to define optimized treatments. Materials and methods During the Sustainable, Environmental Treatment and Reuse of Marine Sediment (SETARMS) project, 13 sediments were dredged from different ports of each side of the Channel Sea, France. Out of these, four representative sediments were chosen to build an experimental subgrade road layer. In order to meet necessary mechanical criteria, optimal treatment mix design was studied in the laboratory and applied in the field. Experimental sections were built with the usual equipment used for road construction. During 1?year of monitoring, different in situ tests were performed such as plate load test, Westergaard Test and cone penetration test. Additionally, unconfined compressive and indirect tensile tests were carried in the laboratory on samples collected by core boring. Results and discussion Results from plate load test (EV2) show that, at 7?days, treated sediments satisfy the minimum value. Core specimens show a better mechanical behaviour than laboratory samples (twice to seven times). However, it has been noticed that results obtained from plate load test and core specimens seem to depend on the spot tested. For instance, standard deviation of unconfined compressive strength results from core samples reached 40%. These observations were confirmed by cone penetration test results. It shows that, according to the tested area, there is strength heterogeneity in the material. Conclusions This study shows that, using an adapted treatment formulation, sediment can be used as an alternative material for subgrade road layer. However, it is necessary to improve the placement and implementation methods to insure the homogeneity of the subgrade road layer. ]]>