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Transportation Research Procedia 17 (2016) 359 - 368
11th Transportation Planning and Implementation Methodologies for Developing Countries, TPMDC 2014,10-12 December 2014, Mumbai, India
Rehabilitation by in-situ cold recycling technique using reclaimed asphalt pavement material and foam bitumen at vadodara halol road
project (SH 87) - a case study
Hari Bhavsara, Rajiv Dubeya, Vishwas Kelkara* a IL&FS Transportation Networks Ltd, Mumbai, India
Transportation Research
Procedia
www.elsevier.com/locate/procedia
Abstract
Cold Recycling Technology (CRT) of worn out bituminous pavement is a relatively new technology which has important application in the road surface treatment and paving towards green highway. Due to economic and environmental constraints like reduction in construction cost, preservation of aggregate and binder, etc, more attention is turning towards recycling of bituminous surface as an alternative to conventional pavement rehabilitation. The objective of this paper is to analyze flexible pavement with insitu cold recycling technique using Reclaimed Asphalt Pavement Material (RAP) and Foam Bitumen. As a case study, pilot project consisting of segregated stretches having major distresses and totaling 10 km length were selected on Vadodara Halol Road Project (SH 87) where cold recycling technique using reclaimed material and foam bitumen was used as a part of rehabilitation of flexible pavement instead of conventional overlay in order to achieve economy and executing within limited time period. Various field as well as laboratory tests are conducted and representative cores were extracted to investigate the pavement characteristics. The results of tests conducted on the cold recycling surface are very encouraging and adopted CRT is found to be economically viable also.
©2016 The Authors.PublishedbyElsevierB.V. Thisis an open access article under the CC BY-NC-ND license (http://creativecommons.Org/licenses/by-nc-nd/4.0/).
Peer-review under responsibility of the Department of Civil Engineering, Indian Institute of Technology Bombay
Keywords: Insitu Cold Recycling Technique; Reclaimed Material; Foamed Bitumen; Indirect Tensile Strength; Economic Evaluation.
* Corresponding author. Tel.: +91-9099095887 E-mail address: vishwas.kelkar@ilfsindia.com
2352-1465 © 2016 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).
Peer-review under responsibility of the Department of Civil Engineering, Indian Institute of Technology Bombay doi:10.1016/j.trpro.2016.11.126
1. Introduction
According to Kamran et al [4] road transportation system is one of the key components in social and economic development of a country and it takes a considerable amount of national budget. Construction materials preservation, environment friendly construction, speedy and cost effective rehabilitation alternatives are the requirements of current age. M. Amaranatha et al [2] described that conservation of energy and materials is important practices for achieving sustainability in road construction. Major road infrastructure activities currently under taken by different agencies in India for the last one decade have shown greater impact on energy consumption and depletion of aggregates. There is a problem with non-availability of good quality aggregates in some states of the country and aggregate being very expensive because of large lead distances. It is also to be noted that thicknesses of existing pavements are increasing due to addition of periodic overlays. The rise of road levels causes serious drainage problems in the urban areas.
Even well designed road pavements reach a phase where the general condition demands rehabilitation for their structural and functional quality. The rehabilitation could be undertaken through an overlay consisting of one or more bituminous layer or through reutilization of existing pavement materials eventually with an improvement of their characteristics defined as pavement recycling.
Defined in handbook of Wirtgen cold recycling technology [5] pavement recycling is one of the technique by which one can address the scarcity of the natural material. In pavement recycling we use the aggregates obtained by cutting and milling of the existing pavement and by doing this we not only conserve the virgin aggregates but also address drainage problem and save millions of rupees. In situ cold recycling technique is environmental friendly, utilizes fewer amount of fuel as well faster in construction. Use of Reclaimed Asphalt Pavement (RAP), obtained from milling of existing distressed bituminous surfacing in pavement construction and rehabilitation works is being routinely used in developed countries for conserving natural resources.
The objective of this paper is to analyze flexible pavement with insitu cold recycling technique using RAP / reclaimed material and foam bitumen. As a case study, pilot project consisting of segregated stretches having major distresses and totaling 10 km length were selected on Vadodara Halol Road Project (SH 87) where cold recycling Technique using reclaimed material and foam bitumen was used as a part of rehabilitation of flexible pavement. Vadodara Halol Road Project was commissioned in year 2000. The project road is four lane divided carriageway. Over a period, due to conventional overlay the thickness of bituminous layer increased excessively. Even after regular maintenance and rehabilitation, various distresses like segregation, severe cracking like alligator cracking, longitudinal cracking, etc undulation and rutting at segregated locations on the pavement were observed. Beyond a point distresses in the lower bituminous layers could not be curtailed as they surfaced after plying of traffic. Also the profile correction had reached its limits because of kerb height. Various field as well as laboratory tests were conducted and representative cores were also extracted on existing bituminous pavement to investigate the pavement characteristics and collecting data for design.
On the basis of results and considering design period of 10 years and 28 msa, conventional overlay was designed as per IRC 81:1997. In order to achieve economy and executing within limited time period, option of Insitu cold recycling technique was also considered.
Foam bitumen mix using RAP, virgin aggregate and bitumen proportioned was produced as per Cold Recycled mix design was produced. A 180mm thick foam bitumen RAP mix layer was prepared and over it 40mm thick bituminous concrete layer was laid. Laboratory investigation like Indirect Tensile Strength (ITS) on specimen of recycled mix and field investigation like Benkleman Beam Deflection (BBD) and Roughness Survey by 5th Wheel Bump Integrator was conducted. Laboratory and field test were conducted on rehabilitated surface before and after one monsoon season. Due to lack of availability of standards on foam bitumen in India, BSG guideline (TG-2, 2009) is adopted for mix design. At present the pavement surface seems to be intact without any visible distress. The results of tests conducted on the new surface have so far been very encouraging.
2. Literature review
Insitu cold recycling is being considered to be an efficient and effective method in the developed countries for rehabilitating asphalt roads showing non-structural aging and cracking of the pavement layer.
In rehabilitation of pavement using foam bitumen, the bitumen is heated in a chamber and cold water is injected into the hot bitumen resulting in the spontaneous formation of foam with huge expansion of bitumen. The foam bitumen
is added to the Reclaimed Asphalt Pavement (RAP) and virgin aggregates. As per TG-2 [6] foamed bitumen is a hot bituminous binder which has been temporarily converted from a liquid state to a foam state by the addition of a small percentage of water and pressurized air. This is mainly a physical rather than a chemical process. Foamed bitumen is characterized by Expansion Ratio (ER) and Half-life time (t'A). The expansion ratio is defined as the maximum volume over its original volume (before foaming) and half-life time is defined as the time it takes (in seconds) for foam to become a half of its maximum volume. The optimum foaming water content is determined by the amount to obtain the maximum expansion ratio and the longest half-life time of foamed bitumen. The expansion of the bitumen and the half-life time are dependent mainly on: the type and temperature of base bitumen, the working pressure of bitumen, water and air, the quantity of foamant water added and temperature of the mixing chamber or vessel into which the foamed bitumen is sprayed.
This cold recycling technique can be used to treat both marginal and recycled materials and applied as base and subbase layers in pavements.
The advantages of cold recycling with foam bitumen highlighted by Kamran et al [4] and handbook of Wirtgen cold recycling technology [5] are hereafter.
• Increase in strength over granular pavement material due to improved cohesion and moisture resistance.
• Quick construction method comparing with other hot mix technology
• Lower cost than reconstruction by utilizing RAP material.
• Bitumen stabilized material are not temperature sensitive.
• As only bitumen is required to be heated and not aggregate or RAP material, this technology is environmental friendly.
• Also due to less fuel consumption there is appreciate cost saving.
2.1. Mix design outline.
Defined by handbook of Wirtgen cold recycling technology [5] mix design procedure involves several steps and one or more levels depending on magnitude of design traffic. The mix design procedure starts with testing of materials to be stabilized and then commencing mix design Level 1 that provides an indication of application rate of bitumen and active filler required to achieve an indicated class of Bitumen Stabilized Materials (BSM). Thereafter depending on requirement of design traffic additional series Level 2 & 3 are adopted to refine application rate and gain confidence in performance potential of treated material. In this paper Level 1 mix design procedure is adopted.
2.2. BSM classification.
Described in handbook of Wirtgen cold recycling technology [5] BSM are classified in three classes depending on quality of parent material and design traffic. The three classes of BSM are BSM1, BSM2 and BSM3. In this paper Material Specification requirement for BSM1 is adopted. BSM1 material has high shear strength and is used as a base layer for design traffic.
Table 1: Material indicators for bitumen stabilized material -1 with foamed bitumen
Test or Indicator Material Used For BSM-1 Codal Provision
Material passing 0.075 mm CS or RAP 0- 10 TG-2
Field Density All > 98% IS:2720 (Part-8 & 28)
Plasticity Index CS or RAP <4 IS:2720(Part5)
ITS (Dry) kpa 100 mm dia Marshall >225 TG-2
ITS (Soaked) kpa Mould > 100 TG-2
ITS (Dry) kpa 150 mm dia Marshall > 175 TG-2
ITS (Soaked) kpa Mould > 150 TG-2
Note: CS - Crushed stone, RAP - Reclaimed Asphalt Pavement Material
2.3. Gradation
The grading of material requires careful considerations. The grading requirement for BSM-Foam for BSM-1 classification as per TG-2 [6] is adopted in this paper.
Table 2: Gradation for BSM-foam
I S Sieve (mm) 50 37.5 26.5 19 13.2 9.5 6.3 4.75 2.36 1.18 0.6 0.425 0.3 0.15 0.075
87 77 66 67 49 40 35 25 18 14 to 28 12 10 7 4
Ideal 100 to to to To to To To to to to to to to
Percent 100 100 99 87 74 62 56 42 33 26 24 17 10
Passing Less Suitable — — 100 99 to 100 87 to 100 74 to 100 62 to 100 56 to 95 42 to 78 33 to 65 28 to 54 26 to 50 24 to 43 17 to 30 10 to 20
Foam bitumen requires sufficient fines particles to be present in the material to facilitate the dispersion of the bitumen. Where the material is deficient in fines, a poor mix will result. For this reason minimum requirement specified is 5% by mass for fines passing 0.075mm sieve. The general grading requirements for BSMs are indicated in terms of zones of most suitable aggregate composition in Figure 1.
Fig.l. Grading requirement in terms ofzones
2.4. Active filler
According to handbook of Wirtgen cold recycling technology [5] filler shall consist of finely divided mineral matter such as Portland cement, hydrated lime or rock dust as approved by Engineer. The filler shall be graded within limits indicated in Table 500-9 of MORT&H specification and shall be free from organic impurities. In this paper for cold mix blend 1% OPC was adopted.
Table 3: Application rate for cement or hydrated lime as filler
Plasticity index: < 10 Plasticity index: 10-16 Plasticityindex: >16
Add 1% Ordinary Portland cement Add 1% Hydrated Lime Pre Heat with 2% Hydrated Lime
2.5. Foaming properties
Foamed bitumen is a mixture of air, water and bitumen and the proportion of 98% bitumen, 1% water & 1% foaming agent (compressed air) was adopted for preparing foam bitumen in this paper. The minimum foaming properties that is acceptable for effective stabilization as per TG-2 [6] is as per table below.
Table 4: Foam characteristics limits (minimum value)
Aggregate Temperature 100Cto25°C Greater Than 25o C
Expansion Ratio, ER (Times) 10 8
Half Life, (Sees) 6 6
If these requirement does not meet than the bitumen should be rejected as unsuitable for foaming.
2.6. Indirect Tensile Strength Test (ITS)
Defined in TG-2 [6] the ITS test is used as an indirect measure of the tensile strength and flexibility of the BSM to reflect the flexural characteristics of the material. It is the most economical method for investigating the effectiveness of the bitumen. The ITS test is used to test the specimen under different moisture condition like dry, soaked and equilibrium moisture content. The ITS is determined by measuring the ultimate load to failure of a specimen that is subjected to a constant deformation rate of 50.8 mm/minute on its diametric axis.
Indirect Tensile Strength (ITS) = (2xP)/(nxhxd)x 10000 where,
P = Maximum applied load, H = Average height of specimen, D = diameter of specimen
Place the specimen under water at 25°C for 24 hours. Remove the specimen from water, surface dry and repeat the procedure to determine the ITS of soaked specimen. The tensile strength ratio is the relationship between the soaked and unsoaked ITS for a specific batch of specimen, expressed as a percentage using equation:
Tensile Strength Ratio (TSR) = (Soaked ITS / Unsoaked ITS) x 100
The TSR is useful to identify problem materials. Where a material has a TSR less than 50%, and the ITSdry exceeds 400 kPa, the material is likely to contain clays and the bitumen is ineffective.
2.7. Determination of optimum binder content
The 100 mm dia Marshall Specimen are tested for indirect tensile strength under dry and soaked conditions. The results of the dry and soaked ITS test are plotted against respective bitumen content that was added. The added bitumen content that best meets the desired properties is regarded as optimum binder content.
3. Existing pavement investigation
The segregated locations were selected along the project road and were considered for rehabilitation by In situ cold recycling.
Table 5: Selected stretches for rehabilitation
Left Carriageway From To 9.000 10.000 17.000 18.000 22.000 23.000 23.000 24.000 24.000 25.000 25.000 26.000 30.000 31.000
Right Carriageway From To 20.000 21.000 21.000 22.000 25.000 26.000 26.000 27.000 29.000 30.000 30.000 31.000 35.000 36.000
The pavement investigation on selected stretches on existing pavement was carried out for rehabilitation. The activities like Pavement Condition Survey, Roughness survey, BBD test and existing pavement bituminous layer Tk were conducted under pavement investigation.
3.1. Pavement condition survey
The pavement condition was carried out prior to commencement of BBD test. The pavement condition survey was conducted by visual observations and collecting details regarding the distresses that have crop up on existing pavement. On conducting pavement condition survey it is observed that various distress exists in varying percentage on entire road project. The distress that were observed are alligator cracks, reflection cracks, stripping, ravelling, pot hole, undulations, etc. At very few locations minor rutting or settlement were observed. This indicates that the existing pavement is structurally sound from base. The photos of the distresses observed at selected stretches are presented below.
Km 9+400 LCW Km 22+200LCW Km 30+200LCW Km20+100RCW Km 26+900RCW Km35+600RCW Fig.2. Photographs offew stretches with distresses
3.2. Roughness survey
The pavement roughness is defined as the irregularities in the pavement surface that affect the ride ability of a vehicle and thus causes discomfort to road users. The roughness survey on selected stretches was carried out by using 5th Wheel Bump Integrator (Automatic Road Unevenness Recorder) towed by Scorpio Gateway utility vehicle. The vehicle attached with 5th Wheel Bump Indicator was moved along the wheel paths at an averagely speed of 30 Km/hr over the slow lane & fast lane of both left carriageway & right carriageway of project road. The roughness data was measured at every 100m interval. The roughness value in mm/Km for fast lane & slow lane of right carriageway & left carriageway is presented in table below.
Table 6: Roughness value in mm/Km on existing pavement at selected stretches_
Chainage (in Km) Left carriageway Chainage (in Km) Right carriageway
From To Slow Lane Fast Lane From To Slow Lane Fast Lane
9.000 10.000 2600 2524 20.000 21.000 2800 2724
17.000 18.000 2712 2590 21.000 22.000 2682 2576
22.000 23.000 2740 2616 25.000 26.000 3000 2890
23.000 24.000 2500 2432 26.000 27.000 2620 2534
24.000 25.000 2262 2220 29.000 30.000 2600 2564
25.000 26.000 2590 2470 30.000 31.000 2858 2766
30.000 31.000 2602 2520 35.000 36.000 2690 2614
3.3. Benkelman Beam Deflection (BBD) test
BBD test was undertaken on carriageway to determine the residual strength of the existing pavement. The test was carried in accordance with IRC: 81-1997 "Guidelines for Strengthening of Flexible Road Pavement using Benkelman Beam Deflection Technique". The readings taken during the test are used for arriving characteristic deflection. The pavement temperature and subsoil moisture correction factor was also considered. The achieved characteristic deflection is presented in table below.
Table 7: Characteristic deflection in mm on existing pavement at selected stretches
Left hand side carriageway Chainage (in Km) Characteristic
deflection
Right hand side carriageway Chainage (in Km) Characteristic
deflection
9.000 10.000 1.48 20.000 21.000 1.36
17.000 18.000 1.65 21.000 22.000 1.53
22.000 23.000 1.14 25.000 26.000 1.42
23.000 24.000 1.60 26.000 27.000 1.67
24.000 25.000 1.28 29.000 30.000 1.39
25.000 26.000 1.59 30.000 31.000 1.39
30.000 31.000 1.46 35.000 36.000 1.18
3.4. Existing pavement bituminous layer thickness
Due to overlay and patchwork the bituminous layer thickness has been increased excessively resulting in kerb height reaching the limit. In order to verify the same, cores were extracted at different locations of selected stretches and the thickness of bituminous layer is provided in table below.
Table 8: Existing pavement bituminous layer Tk in mm at Selected Stretches
Left Hand Side Location 9+500 22+550 23+500 24+700 25+650 30+400
Carriageway BT Tk in mm 220 230 210 180 220 230
Right Hand Side Location 20+300 25+500 26+300 29+500 30+000 35+600
Carriageway BT Tk in mm 200 210 200 280 220 210
4. Proposal for rehabilitation
On the basis of pavement investigation collaborating roughness survey and BBD test results, proposal for rehabilitation by conventional overlay and cold recycling was evaluated and compared. On the basis of traffic data collected and analysed, the rehabilitation was designed considering design period oflO years and 28 msa.
4.1. Conventional overlay
The overlay bituminous thickness is derived based on characteristic deflection and projected msa as per design chart given in IRC: 81-1997. The overlay thickness in terms of Bituminous Macadam (BM) layer established as per design chart is accordingly converted into DBM (Dense Bituminous Macadam) & BC (Bituminous Concrete). The proposed bituminous overlay for strengthening the existing pavement is presented in table below.
Table 9: Proposed bituminous overlay as per conventional method_
Left carriageway Right carriageway
Chainage (in Km) Character -istic deflectio BM in Overlay Chainage (in Km) Characteri -stic deflection BM in Overlay
From To mm proposal From To mm proposal
9.000 10.000 1.48 151.57 40mm BC + 70mm DBM 20.000 21.000 1.36 137.75 40mm BC + 60mm DBM
17.000 18.000 1.65 166.79 40mm BC + 80mm DBM 21.000 22.000 1.53 156.52 40mm BC + 70mm DBM
22.000 23.000 1.14 103.03 40mm BC + 50mm DBM 25.000 26.000 1.42 145.03 40mm BC + 65mm DBM
23.000 24.000 1.60 162.76 40mm BC + 75mm DBM 26.000 27.000 1.67 168.31 40mm BC + 80mm DBM
24.000 25.000 1.28 126.71 40mm BC + 50mm DBM 29.000 30.000 1.39 141.49 40mm BC + 60mm DBM
25.000 26.000 1.59 161.91 40mm BC + 75mm DBM 30.000 31.000 1.39 141.49 40mm BC + 60mm DBM
30.000 31.000 1.46 149.47 40mm BC + 65mm DBM 35.000 36.000 1.18 110.43 40mm BC + 50mm DBM
4.2. Cold recycling
It was observed that the bituminous layer thickness of existing pavement at selected stretches that were distressed excessively was averagely 220 mm. It was decided to replace 220mm thickness of bituminous layer of existing pavement by 180 mm of cold insitu recycle layer + 40 mm fresh bituminous concrete layer as wearing course. After conducting number of trial with varying blending proportions of RAP, 20mm virgin aggregate & Cement, the blending as shown below falls within the specified limits and was adopted.
Table 10: Coldmixmaterialblending
IS sieve (mm) 45 37.5 26.5 19 13.2 4.75 2.36 0.600 0.300 0.150 0.075
RAP 100 100 100 90.5 82.34 44.36 33.87 21.45 16.65 11.25 5.7
% Passing 20 mm 100 100 100 71.93 27.11 2.07 0.15 0.04 0.02 0.01 0.01
Cement 100 100 100 100 100 100 100 100 100 100 98
Blending (RAP 91%+ 20mm 8% + OPC 1%) 100.00 100.00 100.00 89.11 78.10 41.53 31.83 20.52 16.15 11.24 6.17
Mid limit 100.00 93.50 88.50 82.50 77.00 45.50 33.50 21.00 17.00 12.00 7.00
Lower limit 100 87 77 66 67 35 25 14 10 7 4
Upper limit 100 100 100 99 87 56 42 28 24 17 10
On finalizing the cold mix with blending proportion of 91% RAP, 8% 20mm virgin aggregate & 1% Ordinary Portland Cement (OPC), the modified proctor test was conducted as per IS: 2720 Part 8 to determine Maximum Dry Density (MDD) in gm/cc and Optimum Moisture Content (OMC) in percentage. On achieving MDD and OMC, foamed bitumen mix samples were prepared by mixing blended mix with foam bitumen. VG 10 bitumen was used for preparing foam bitumen with proportion of 98% bitumen, 1% water &1% foaming agent (Compressed Air). The foam bitumen properties were verified prior to cold mix preparation. Total 18 numbers of foam bitumen mix samples were prepared with 6 samples for each percentage of 1.8%, 2% and 2.2% of foam bitumen. The Foam bitumen mix sample of 100 mm dia was prepared adopting Marshall Method. Out of 18 foam bitumen mix samples prepared, 9 samples were tested for ITS dry condition and remaining 9 samples for ITS wet condition. The Indirect Tensile Strength (ITS) Test is conducted as per ASTM: D 6931 - 12 to determine Optimum Bitumen Content (OBC) to be adopted. The obtained results for foam bitumen as well modified proctor and Indirect Tensile Strength (ITS) on cold recycle mix are presented below.
Table 11: Test results for Reclaimed Asphalt Pavement (RAP) material and virgin 20mm aggregate_
Reclaimed Asphalt Pavement Material (RAP) Virgin 20mm Aggregate
Parameters Results Parameters Results
Unit weight (gm/cc) 2.20 Bulk specific gravity (Oven dry) 2.826
Optimum moisture content (%) 5.00 Bulk specific gravity (SSD) 2.847
California bearing ratio (%) 24.20 Water absorption (%) 0.72
Aggregate impact value (%) 12.10 Aggregate impact value (%) 10.20
Aggregate abrasion value (%) 13.20 Aggregate abrasion value (%) 12.30
Parameters Results
Expansion Ratio, ER (Times) 24
Half Life, (Sees) 11
Table 13: Test results for modified proctor & ITS
Maximum dry density (g/cc) 2.42 Optimum moisture content (%) 6
Summary for Indirect Tensile Strength Test (ITS)
Bitumen content (%) Average ITS Dry (kPa) Average ITS wet (kPa) Tensile Strength Ratio (TSR) (%)
1.8 367.90 313.80 85
2.0 331.11 269.15 81
2.2 284.64 218.80 77
Cr nJiHilartjMurtmin
^frT. WW
L&y, 1JLU
wrt MS, IJ
WK. J1» K
Fig.3. Graph for OBC
From the above results of ITS and TSR as well graph plotted for ITSdry and ITSwet against % foam bitumen, it was observed that the achieved results satisfies the required criteria for all three percentage of foam bitumen. Even though results were satisfying at 1.8% foam bitumen, but looking to percentage of finer material it was decided to adopt 2% foam bitumen for cold recycle mix to be on a safer side.
5. Construction methodology adopted
It was decided to replace 220 mm thick existing bituminous pavement by 180 mm of in situ cold recycled layer and 40 mm bituminous concrete layer as wearing course. The cold recycle mix consist of91% RAP material + 8% virgin 20 mm aggregate +1% OPC + 2% foam bitumen. The top 66 mm of existing bituminous pavement was milled and discarded to compensate 40 mm thick fresh BC layer and 26 mm thickness to accommodate additional 8% virgin aggregate. After milling 66 mm of existing bituminous pavement, 20 mm virgin aggregate and 1% OPC in proportion was spread on the milled surface. The remaining 154 mm thick existing bituminous pavement along with layer of 20 mm virgin aggregate and OPC was pulverized with 2% foam bitumen at in situ by WR 2400. The recycled cold mix was then compacted using heavy compactor to achieve required density. Finally 40 mm BC wearing course was laid on top of cold recycled surface.
Fig.4. Photograph of Cold Recycle Construction in Progress
6. Investigation on rehabilitated (cold recycled) stretch
After cold recycling at selected stretches and allowing drying for one day, field density test was conducted to verify the compaction. Moreover few representative cold recycle cores were extracted for ITS testing. Also BBD testing and roughness survey were conducted on the selected stretches. As planned, the set of testing were conducted on selected stretches before monsoon season and also after monsoon season.
Table 14: Test results for field density & % compaction achieved
Location 22+550 LCW 23+500 LCW 25+650 LCW 30+400 LCW 20+300 RCW 25+500 RCW 30+000 RCW 35+600 RCW
FDD(g/cc) 2.38 2.38 2.40 2.40 2.39 2.40 2.39 2.40
% Compaction ^ ^ Achieved ' 98.5 99.0 99.1 98.7 99.2 98.6 99.3
Table 15: ITS & TSR results on cold recycled core specimen after cold recycling.
Location 9+600 LCW 17+300 LCW 24+300 LCW 30+500 LCW 21+700 RCW 26+400 RCW 29+600 RCW 30+600 RCW
Average ITS Dry(kPa) 341.51 337.12 335.25 338.12 339.12 333.65 335.28 336.19
Average ITS Wet (kPa) 278.89 270.54 271.23 273.21 274.61 269.17 270.69 271.52
Tensile Strength Ratio (%) 82 80 81 81 81 81 81 81
368 Hari Bhavsar et al. / Transportation Research Procedia 17 (2016) 359 — 368 Table 16: Roughness value in mm/Km on cold recycled surface at selected stretches_
Chaînage Left carriageway Chaînage Right carriageway
(in Km) Before Monsoon After Monsoon (in Km) Before Monsoon After Monsoon
From To Slow Fast Slow Fast From To Slow Fast Slow Fast
Lane Lane Lane Lane Lane Lane Lane Lane
9.000 10.000 1990 1944 2010 1976 20.000 21.000 2005 1965 2020 1972
17.000 18.000 1978 1928 2000 1948 21.000 22.000 1902 1872 1900 1878
22.000 23.000 1970 1932 1998 1952 25.000 26.000 1865 1887 1958 1906
23.000 24.000 2080 2024 2110 2070 26.000 27.000 2020 1970 2050 1976
24.000 25.000 1956 1900 2000 1928 29.000 30.000 2000 1952 2090 2064
25.000 26.000 1900 1876 1940 1900 30.000 31.000 1942 1900 1980 1958
30.000 31.000 2050 2002 2090 2042 35.000 36.000 1834 1780 1840 1806
Table 17: Characteristic deflection in mm on cold recycled surface at selected stretches
Left carriageway Right carriageway
Chainage Characteristic deflection Chainage Characteristic deflection
(in Km) (in mm) (in Km) (in mm)
From To Before Monsoon After Monsoon From To Before Monsoon After Monsoon
9.000 10.000 1.19 1.21 20.000 21.000 1.06 1.08
17.000 18.000 1.33 1.34 21.000 22.000 1.21 1.24
22.000 23.000 0.99 1.01 25.000 26.000 1.14 1.15
23.000 24.000 1.21 1.24 26.000 27.000 1.27 1.30
24.000 25.000 1.08 1.11 29.000 30.000 1.11 1.12
25.000 26.000 1.15 1.18 30.000 31.000 1.05 1.09
30.000 31.000 1.08 1.10 35.000 36.000 0.98 0.99
7. Conclusion
Based on achieved test results of cold recycled with foam bitumen, following conclusions can be drawn:
• On analyzing the roughness survey and deflection value between existing bituminous surface and cold recycled surface, it was observed that there was significant improvement.
• Moreover roughness survey and deflection value on cold recycled surface before and after monsoon season remains almost near.
• The Indirect Tensile Strength (ITS) & Tensile Strength Ratio (TSR) for cold recycle mix during mix design and for cold recycle core specimen after cold recycling, both satisfies the required criteria.
• The field density & % compaction of cold recycled surface is found satisfactory.
• From the laboratory as well field evaluation of recycled pavement using foam bitumen, it appears that CRT is promising alternative for rehabilitation of in service pavement.
• Looking to construction cost and the present performance of CRT we expect of saving around 15% in 10 years of cycle cost.
8. References
[1] Felice Giuliani, Silvia Rastelli, "An Analytical Approach to Evaluate the Performance of Cold Recycled Asphalt Mixture".
[2] M. Amaranatha Reddy, K Sudhakar Reddy & B.B. Pandey "Recycling of an Urban Road using Foam Bitumen: An Indian Experience"
[3] K. Kranthi Kumar, R. Rajashekhar, M. Amaranatha Reddy & B.B.Pandey "Reclaimed Asphalt Pavement in Bituminous Mixes", (April 2014), Indian Highways.
[4] Kamran Muzaffar Khan, Mumtaz Ahmed Kamal, Faizan Ali, Shiraz Ahmed & Tahir Sultan (2012) "Performance Comparison of Cold in Place Recycled and Conventional HMA Mixes", IOSR-JMCE, PP 27-31.
[5] Wirtgen Cold Recycling Technology (2010), Wirtgen GmbH, Third Edition, Germany.
[6] Technical Guideline(TG 2), Asphalt Academy, 2nd Edition (May 2009), Pretoria, South Africa.
