Onsite Use of Recycled Asphalt Pavement Materials and Geocells to ...

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Chapter 5 Conclusions and Recommendations The experimental work was carried out on unreinforced and geocell-reinforced flexible pavements with recycled asphalt pavement (RAP) bases under cyclic loading in the large geotechnical testing box at the University of Kansas. These tests simulated onsite use of RAP with geocell as bases overlaid by thin hot mix asphalt (HMA) surfaces to support heavy trucks. Six experiments were carried out by varying the thickness of the base course with and without geocell confinement. 5.1 Conclusions Based on the test results, the following conclusions can be drawn: 1. The vane shear test, dynamic cone penetration test, and light weight deflectometer test were effective methods for quality control for subgrade, base course, and hot mix asphalt (HMA) surface during the preparation of test sections. 2. The novel polymeric alloy (NPA) geocell reinforcement significantly reduced the permanent deformation of the flexible pavement and increased the pavement life by a factor of 10. 3. The thinner geocell-reinforced base section had equivalent performance to the thicker unreinforced base section. In this study, the 15 cm thick geocell-reinforced RAP base was equivalent to the 30 cm thick unreinforced RAP base. 4. The geocell confinement increased the stiffness of the base course and reduced the compression of the base course. 5. The geocell-reinforced RAP bases provided a solid foundation for better compaction of the HMA surface and resulted in lower percent of air void in the HMA surface. 116
6. The subgrade contributed to most of the total permanent deformation, followed by the RAP base and the HMA surface. 7. The geocell-reinforced base acted as a semi-rigid mattress foundation, which distributed the applied load to a wider area on the subgrade with higher stress distribution angle and resulted in lower compression of subgrade, RAP base, and HMA surface layers as compared with unreinforced base sections. 5.2 Recommendations This experimental study of geocell-reinforced flexible pavements with RAP bases is the original research on the geocell technology for flexible pavement applications. The experimental results from this study can be used as a basis for numerical modeling and development of a design method in the future. The following work should be carried out to further advance the geocell technology for flexible pavement applications: 1. Investigate the effects of subgrade CBR and HMA thickness on the pavement performance; 2. Develop a method to quantify the benefit of geocell confinement; 3. Verify the cyclic plate load test results with accelerated moving wheel load tests and/or field trafficking tests; and 4. Develop a design method for geocell-reinforced flexible pavements with RAP bases. 117
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Report # MATC-KU: 462 Final Report
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Technical Report Documentation Page
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4.3.4 15 cm Thick Geocell-Reinforce
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Figure 4.11 Profiles of the HMA sur
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Figure 4.48 The permanent deformati
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List of Tables Table 2.1 Percentage
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Acknowledgements This research was
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Abstract Asphalt pavements deterior
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1.1 Background Chapter 1 Introducti
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On-site use of RAP materials has re
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Chapter 2 Literature Review Recycle
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Protection. Geosynthetics are somet
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wet weather conditions. Webster and
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subgrade can be improved in terms o
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annually in the early 1990s (FHWA-H
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Figure 2.2 Usage and potential of v
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Table 2.1 Percentage of use of RAP
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Type of Property Physical Propertie
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permeability values. The addition o
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Chapter 3 Material Properties and E
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Table 3.1 Properties of the RAP bas
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3.3 Asphalt Concrete Figure 3.4 Sta
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Table 3.2 Basic Properties of NPA g
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Earth pressure cells were installed
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central pocket, and one at the top
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plate on one end was buried at the
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loading plate to simulate the rubbe
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3.6.7 Dynamic Cone Penetration Test
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Figure 3.15 Light weight deflectome
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Chapter 4 Experimental Data Analysi
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The quantity of RAP placed in each
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Geocell infilled with RAP Geocell i
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Figure 4.4 Prime coat on the RAP ba
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4.2 Cyclic Plate Load Tests Figure
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dynamic deformation moduli from LWD
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Depth (cm.) 0.00 5.00 10.00 15.00 2
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Depth (cm.) 10 14 18 22 26 Before t
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surface at the center was under ten
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4.3.3 15 cm Thick Geocell-Reinforce
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Depth (cm.) 0 10 20 30 40 50 60 0 5
Page 81 and 82: The permanent deformation was obtai
Page 83 and 84: Strain on geocell (%) Figure 4.23 T
Page 85 and 86: Stress distribution angle (°) 50 4
Page 87 and 88: Figure 4.28 The calculated dynamic
Page 89 and 90: Elastic deformation (mm.) 3 2.5 2 1
Page 91 and 92: Strain (%) 0.15 0.1 0.05 0 -0.05 -0
Page 93 and 94: 4.3.5 23 cm Thick Geocell-Reinforce
Page 95 and 96: The profiles of the HMA surfaces as
Page 97 and 98: Figure 4.41 shows the measured maxi
Page 99 and 100: Figure 4.43 The vertical stress at
Page 101 and 102: Table 4.5 The average CBR values of
Page 103 and 104: at the distances of 25 and 50 cm aw
Page 105 and 106: Strain (%) 0.014 0.012 0.01 0.008 0
Page 107 and 108: 4.3.7 30 cm Thick Geocell-Reinforce
Page 109 and 110: The profiles of the HMA surfaces as
Page 111 and 112: Figures 4.58 and 4.59 show the meas
Page 113 and 114: Strain (%) 0.04 0.02 0 -0.02 -0.04
Page 115 and 116: 4.4 Analysis of Test Data Six cycli
Page 117 and 118: Table 4.7 Average CBR values of tes
Page 119 and 120: The percentages of air void of the
Page 121 and 122: Table 4.10 Number of loading cycles
Page 123 and 124: Table 4.11 Elastic deformation and
Page 125 and 126: HMA surface compression (mm.) Base
Page 127 and 128: strain was higher for the geocell a
Page 129 and 130: Vertical stress (kPa) 250 200 150 1
Page 131: Stress distribution angle ( ̊) 80
Page 135 and 136: Berthelot, C., R. Haichert, D. Podb
Page 137: Pokharel, S. K., J. Han, D. Leshchi
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Onsite Use of Recycled Asphalt Pavement Materials and Geocells to ...

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