Formulation of optimized excavatable cement treated materials using a new punching test aparatus
Résumé
Classical techniques for backfilling of trenches use unbounded materials. Unfortunately, they have always been presenting several drawbacks: difficulty of compaction, noise disturbance and time of implementation... Controlled Low Strength Materials (CLSM) could be a good alternative thanks to their fluidity and cementitious setting, provided that they remain excavatable, even with a pick. In fact, it is essential to ensure a rapid and easy permanent access to the underlying networks, in case of emergency or maintenance. Modular concrete pavements were developed during the last years for that purpose. The concrete elements are laid on a base of cement treated material to keep their stability. They are designed to be easily removed but the base material must be excavated with a light facility as well. Yet, until recently, the excavatability was not well defined, nor well measured. Recently, a new approach based on a simple laboratory punching test was developed at Ifsttar to provide a quantitative characterization in laboratory of cement treated materials excavatability. This paper first details the general approach. Then a large parametric experimental campaign conducted with the punching test on mixes with various compositions is presented. From the results obtained, a model linking the mix proportions to the pick penetration depth is proposed. Finally, excavations are realized on real scale trenches to confirm that the optimization of the penetration leads to a better excavatability of the material.
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35-Eric Gennesseaux - M&S - 2017 - R2 avec entete.pdf (1.07 Mo)
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