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

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pressure was well distributed within the geocell mattress and was transferred to a wider area of the subsoil compared to the unreinforced sand bed. Latha et al. (2006) conducted laboratory model tests to investigate the benefit of geocell confinement on the performance of earth embankments constructed over weak foundation soil. They evaluated the influence of several factors on the behavior of the embankment, such as tensile stiffness of geocell material, height and length of geocell layer, pocket size of the cell, pattern of formation of geocells, and type of fill material inside the cells. Geocell confinement was found to be beneficial in increasing the bearing capacity and reducing the deformation of the embankment. 2.2 Recycled Asphalt Pavement Materials 2.2.1 Sources and Applications Recycled Asphalt Pavement (RAP) is a removed or reprocessed material derived from existing aged asphalt pavements or plant hot mix asphalt (HMA) waste containing asphalt and aggregate. Generally, asphalt pavements are removed either by milling using a milling machine or full depth removal using a bulldozer or pneumatic pavement breaker. The removed asphalt material is processed using a series of operations including crushing, screening, conveying, and stacking, etc. The RAP is processed either at the central processing plant or on site. According to the National Asphalt Pavement Association (NAPA), it is estimated that U. S. production of asphalt pavement materials is around 500 million tons per year. In 2011, about 60 million tons of RAP were reused or recycled directly into pavements by transportation agencies. In addition, agencies reuse or recycle about 40 million tons of RAP for other pavement related applications every year. About 100 million tons of RAP were used in 2011, compared to 72 million tons used 12
annually in the early 1990s (FHWA-HRT-11-021). High-quality and well-graded aggregates coated with asphalt binder can be obtained when RAP is crushed and screened properly. The use of RAP in pavement construction has become more popular since the mid-1970s, although it was practiced as early as 1915. Previous sustained efforts to recover and reuse old asphalt paving materials in road construction were undertaken in Nevada and Texas in 1974. RAP has been used mostly in hot or cold mix asphalt with virgin asphalt binder and aggregate. In addition, RAP has been used as granular bases or sub-bases, stabilized base aggregate, and embankment fill for constructing roadways, roadbeds, shoulders, and embankments (AASHTO Center for Environmental Excellence 2003). According to the FHWA Pavement Recycling Guidelines (FHWA-HRT-11-021), the recycling or reuse of RAP for pavement construction has the following advantages: (a) reduced cost of construction, (b) preservation of aggregate and binder resources, (c) preservation of the environment, and (d) preservation of energy. According to NAPA, more than 90% of U.S. roads are paved with HMA. As roads become old, transportation agencies face increasing demand for raw materials required to maintain and rehabilitate these roads. Because of growing demand, the scarcity and rising cost of aggregate and binder, and environmental and energy saving considerations, RAP is considered as a viable alternative to virgin aggregate materials in roadway construction. According to the FHWA survey (FHWA-HRT-10-001), as of 2007, the average amount of RAP incorporated into HMA mixtures by state DOTs was 12% by weight. State DOT specifications have set restrictions on the maximum amount of RAP in HMA. If more than 15% RAP is used in a new mix, the required performance grade of the virgin binder should be adjusted. In 2007, the North Carolina Department of Transportation (NCDOT) conducted a survey on behalf of FHWA and AASHTO to determine the level of RAP use across the country, as well 13
Page 1 and 2: Report # MATC-KU: 462 Final Report
Page 3 and 4: Technical Report Documentation Page
Page 5 and 6: 4.3.4 15 cm Thick Geocell-Reinforce
Page 7 and 8: Figure 4.11 Profiles of the HMA sur
Page 9 and 10: Figure 4.48 The permanent deformati
Page 11 and 12: List of Tables Table 2.1 Percentage
Page 13 and 14: Acknowledgements This research was
Page 15 and 16: Abstract Asphalt pavements deterior
Page 17 and 18: 1.1 Background Chapter 1 Introducti
Page 19 and 20: On-site use of RAP materials has re
Page 21 and 22: Chapter 2 Literature Review Recycle
Page 23 and 24: Protection. Geosynthetics are somet
Page 25 and 26: wet weather conditions. Webster and
Page 27: subgrade can be improved in terms o
Page 31 and 32: Figure 2.2 Usage and potential of v
Page 33 and 34: Table 2.1 Percentage of use of RAP
Page 35 and 36: Type of Property Physical Propertie
Page 37 and 38: permeability values. The addition o
Page 39 and 40: Chapter 3 Material Properties and E
Page 41 and 42: Table 3.1 Properties of the RAP bas
Page 43 and 44: 3.3 Asphalt Concrete Figure 3.4 Sta
Page 45 and 46: Table 3.2 Basic Properties of NPA g
Page 47 and 48: Earth pressure cells were installed
Page 49 and 50: central pocket, and one at the top
Page 51 and 52: plate on one end was buried at the
Page 53 and 54: loading plate to simulate the rubbe
Page 55 and 56: 3.6.7 Dynamic Cone Penetration Test
Page 57 and 58: Figure 3.15 Light weight deflectome
Page 59 and 60: Chapter 4 Experimental Data Analysi
Page 61 and 62: The quantity of RAP placed in each
Page 63 and 64: Geocell infilled with RAP Geocell i
Page 65 and 66: Figure 4.4 Prime coat on the RAP ba
Page 67 and 68: 4.2 Cyclic Plate Load Tests Figure
Page 69 and 70: dynamic deformation moduli from LWD
Page 71 and 72: Depth (cm.) 0.00 5.00 10.00 15.00 2
Page 73 and 74: Depth (cm.) 10 14 18 22 26 Before t
Page 75 and 76: surface at the center was under ten
Page 77 and 78: 4.3.3 15 cm Thick Geocell-Reinforce
Page 79 and 80:
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 and 132:
Stress distribution angle ( ̊) 80
Page 133 and 134:
6. The subgrade contributed to most
Page 135 and 136:
Berthelot, C., R. Haichert, D. Podb
Page 137:
Pokharel, S. K., J. Han, D. Leshchi
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