Abstract

RINCON-MORANTES, Jhon Fredy; ALVAREZ, Allex E  and  REYES-ORTIZ, Oscar J. Stiffness Estimation of Unbound Marginal Granular Materials Through Dynamic CBR Test. Ing. Desarro. [online]. 2022, vol.40, n.1, pp.92-113.  Epub Sep 02, 2022. ISSN 0122-3461.  https://doi.org/10.14482/inde.40.01.621.992.

Laboratory evaluation of unbound granular materials response (e.g., paving granular subbases and bases), subjected to dynamic load is limited in Colombia. This state of the practice is related, among other aspects, to the fact that the dynamic triaxial equipment required for its determination is expensive, and the test protocols are complex. In the last decade, work has been carried out to develop the dynamic CBR test (dCBR) that employs the CBR equipment but modifies the testing protocol applied in the CBR test. This research proposes the basis of a new protocol for the dCBR test to determine the stiffness of granular materials (i.e., equivalent resilient modulus) by applying seven steps repeated load, where each step is defined by a target strain. The study included two marginal granular materials (MGMs) with high plasticity indexes. The results suggest that the proposed dCBR test protocol allows for estimating the equivalent resilient modulus. In addition, the proposed protocol differentiates the effect of the plasticity index on the stiffness of the MGM (i.e., reduction of equivalent resilient modulus as the plasticity index increases). Therefore, we propose to extend the range of materials characterized to validate the preliminary results presented and inquire about a possible correlation between the values of resilient modulus and equivalent resilient modulus.

Keywords : dynamic cbr test; marginal granular material; unbound granular material; resilient modulus; equivalent resilient modulus; pavements.

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