Author(s):
I.M. Syed, T. Scullion
Publication Date
December 1998
Abstract
A structural evaluation was performed on 25 base recycling projects in the Bryan District. The recycled layers were stabilized with cement or lime, and each was 250 mm thick. On the higher volume roadways, an unstabilized flexible base was placed over the stabilized layer, followed by a two course surface treatment (2 CST). On the other pavements the 2 CST was placed directly on the stabilized layer. Testing involved the use of the Dynaflect, falling weight deflectometer, dynamic cone penetrometer, and ground penetrating radar. A correlation was generated between the backcalculated layer moduli and the percentage of stabilizer used.|Two visual surveys were completed. In 1997, of the 25 sections evaluated, 23 were judged to be performing well, with little or no surface distress. However, after the severe Texas summer of 1998, only 17 were judged to be performing well. The major distress found was severe localized longitudinal cracking, which originated in the subgrade. The shrink/swell potential of the subgrade soil appears to be the major factor controlling pavement performance. Sections constructed on soils with a plasticity index (PI) of more than 35 did not perform well. The severity of the surface cracking was also related to the following secondary factors: a) the summer droughts of 1996 and 1998, b) the presence of trees near the edge of the pavement, c) the side slope conditions, and d) the strength of the stabilized layer.|In conclusion, the base recycling technique applied by the Bryan District appears to be working if the subgrade soils have low to moderate PIs. This technique is not recommended for sections constructed on high PI subgrades. Recommendations to modify the existing design approach are proposed for these problem areas.
Report Number:
7-3903-S
Keywords:
Base Recycling, Cement, DCP, Dynaflect, FWD, Lime, pavement rehabilitation, Reclamation
Link(s):
Document/Product
http://tti.tamu.edu/documents/3903-S.pdf
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