Recycled Asphalt Improvement Using EnviroGrid® Geocell

EnviroGrid® confines fill material to prevent lateral displacement and add structural support. UT Arlington was contacted by the Texas DOT to study the benefits of cellular confinement using recycled asphalt as infill material. Recycled Asphalt Pavement (RAP) materials have been considered one of the most sustainable and cost-effective options for pavements. The use of RAP materials reduces the depletion of natural resources and the amount of construction debris in landfills.

The low shear strength and high permanent deformation (PD) of RAP materials often limit their application in road bases. The objective of the study was to assess the efficacy of HDPE geocell reinforcements in enhancing the strength and stiffness properties of RAP bases and for mitigating PD behavior to determine if it could be used in place of conventional methods.


A large-scale laboratory box test setup was designed and fabricated to facilitate repeated load tests to evaluate the performance of HDPE geocell-reinforced RAP bases. The test setup consisted of a large steel tank with dimensions 1.83m x 1.83m x 1.52m with:

  • Loading frame, accumulator, and hydraulic pump to control and regulate hydraulic fluid

  • Cyclic load regulator for controlling the repeated load application

  • Load cell to measure the applied load

  • Linear variable displacement transducers (LVDTs) for measuring the vertical surface deformations

  • Data acquisition system to collect the data from the LVDTs and load cell

A circular steel plate of 152.4 mm (6in) diameter and 12.7mm (0.5in) thickness was used to simulate tire contact area.

The 6" geocell reinforcement increased the bearing pressure of RAP at 25% settlement ratio 2 times and the sub-grade modulus showed an improvement of 96%. The maximum percentage of reduction in settlement of the RAP was 75%, showing a significant decrease in vertical deformation. In addition, it was observed that HDPE geocell increased the resilient modulus of the base layer by approximately 3 to 4 times and reduced the permanent deformation of RAP base by 70% to 80%.


It was concluded that the geocell with RAP can be successfully used as a sustainable pavement base alternative for conventional crushed limestone aggregate. The use of geocell reinforcement in the base layer can improve the overall performance of the pavement infrastructure both structurally and sustainably when RAP is used as infill material.

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CS Recycled Asphalt Improvement EGA 30
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