field and laboratory evaluation of winter season pavement

1

Field and Laboratory Evaluation of Winter Season Pavement Patching 1

Materials in Tennessee 2

3

Qiao Dong, Ph.D. 4

Postdoctoral Research Associate 5

Department of Civil and Environmental Engineering 6

The University of Tennessee 7

Knoxville, TN 37996 8

Ph: (865)974-2608 9

Fax: (865)974-2608 10

E-mail: [email protected] 11

12

Baoshan Huang, Ph.D., P.E. 13

Associate Professor 14

Department of Civil and Environmental Engineering 15

The University of Tennessee 16

Knoxville, TN 37996 17

Ph: (865)974-7713 18

Fax: (865)974-2669 19

E-mail: [email protected] 20

21

22

Word Count: Abstract: 228

Text: 5108

Figures: 7 (250 ea)

Tables: 1 (250 ea)

Total: 7108

TRB 2013 Annual Meeting Paper revised from original submittal.

Qiao Dong and Baoshan Huang 2

2

ABSTRACT 1

2

Field survey and laboratory tests were conducted to evaluate the performance of four 3

patching materials used in winter season pothole repair in Tennessee. The adhesiveness, 4

cohesion, moisture susceptibility and loaded wheel test were conducted to investigate the 5

bonding, freeze-thaw resistance and rutting resistance of the patching materials. 6

Statistical analysis on the six month field survey showed that edge disintegration and 7

missing patch are the mainly distress of “throw and roll” patching in winter season. 8

Severe freeze condition, high traffic level and vehicle speed accelerated the deterioration 9

of patching. Patchings with lower depth and larger size especially longer longitudinal 10

length deteriorated faster. Both field and adhesiveness test showed that the cold dump 11

mix had high potential to edge disintegration and missing patch, which is probably 12

caused by the insufficient binder content or an excessive stiff binder. One cold bag mix 13

showed high potential to deformation and low strength performance, mainly due to its 14

single size gradation and weak aggregate skeleton. Cohesion test conducted at different 15

temperature and compaction times presented consistent ranking of materials. 25°C and 15 16

blows were recommended to evaluate the cohesion of materials at moderate temperature. 17

Two cold mixes did not withstand the 60°C water bath in the freeze-thaw cycling due to 18

the high air voids and 25°C was suggested instead. Reduced wheel load is recommended 19

to improve the effectiveness of loaded wheel test for cold patching mixtures. 20

21

Keywords: Pothole; Patching; Cold mix; Adhesiveness; Cohesion; Moisture 22

susceptibility; Loaded wheel test. 23



3

INTRODUCTION 1

2

Background 3 4

Potholes are usually bowl-shaped holes frequently encountered on the surface of flexible 5

pavement. Low severity potholes are less than 1 in. deep, moderate-severity from 1 to 2 6

in. deep and high-severity potholes are deeper than 2 in. (1). Some potholes can penetrate 7

through the HMA layer to the base layer. Unlike raveling, potholes usually have sharp 8

edges and vertical sides at the top. Potholes greatly reduce the pavement performance 9

level and service life, and are the most aggravating pavement distresses for traffic safety. 10

Generally, potholes are the result of alligator cracking, which is a type of severe fatigue 11

failure of the pavement surface. As alligator cracking becomes more severe, the 12

interconnected cracks cause the pavement surface break into small pieces. The broken 13

pieces are then pulled up by travelling wheels and a pothole forms. Freeze-thaw cycles 14

accelerate the formation of potholes. The water inside the pavement expands when it 15

freezes to ice, forcing higher stress on an already cracked pavement. 16

Pothole repair is one of the most commonly performed maintenance operations 17

for many highway agencies, especially in areas where cold winters and warm, wet 18

springs. Pothole repair methods include various combinations of materials and 19

procedures. Patching materials include hot mixed asphalt (HMA) mixture and cold mixed 20

asphalt using either emulsified asphalt or cut-back asphalt. Patching procedure generally 21

includes placing and compacting asphalt mixtures in the potholes, and sometimes 22

cleaning and cutting before patching and sealing edge after patching. The most widely 23

used patching procedures include throw and roll and semi-permanent. Throw and roll 24

includes placing material and compacting with truck tires. Semi-permanent usually 25

includes cut sides, cleaning debris and compacting with specific compactors (2). Other 26

commonly used procedures include spraying edge sealing to seal the patch and heating 27

the old pavement using a infra-red heater. Many highway agencies use throw and roll 28

procedure in winter for temporary repairs while conduct semi-permanent patching in 29

summer as permanent repair (2). 30

31

Previous Studies 32 33

There have been several studies conducted to evaluate the performance and effectiveness 34

of various patching techniques through field survey and laboratory tests. Thomas and 35

Anderson investigated the longevity and cost-effectiveness of different pothole repair 36

methods in the northern states based on field observations (3). They pointed out that 37

material cost is a small percentage of the total cost for pothole repair, and thus innovative 38

or more expensive materials that can provide longer repair longevity will be cost-39

effective. From 1991 to 1996, the Strategic Highway Research Program (SHRP) 40

conducted the most extensive field experiment, the SHRP H-106 project, to determine the 41

most cost-effective combinations of materials and patching procedures for pothole repair 42

(2)(4)(5)(6). Different repair methods were investigated through test sites installed at 43

eight locations in the United States and Canada under the SHRP and LTPP programs. It 44

was found that throw-and-roll technique was as effective as the semi-permanent 45

procedure and was more cost-effectiveness because of the lower labor and equipment. 46



4

Various laboratory tests have been developed to evaluate the performance of 1

different pothole patching materials (7)(8)(9). Virginia Department of Transportation 2

(DOT) evaluated the performance of different cold-mix patching materials through 3

coating test, stripping test, drain down test, cohesion test, workability test and adhesion 4

test (7). In addition to the traditional Marshall Stability and resilient modulus test, New 5

Jersey DOT conducted blade resistance and rolling sieve test to evaluate the workability 6

and cohesion of patching materials by simulating field operation (8). Texas conducted 7

wheel tracking test and indirect tensile strength test to evaluate the stability and strength 8

of cold mixes and developed a slump-based laboratory workability test (9)(10). 9

In addition to the wheel tracking test, accelerated tests on simulated potholes were 10

also proposed to evaluate the performance of pothole under analogue traffic and 11

environment conditions. Texas developed an accelerated pavement test to evaluate the 12

rutting of potholes installed on field by applying an accelerated wheel loading using a 13

mobile load simulator (10). Fragachan (11) evaluated the performance of patching by 14

applying an accelerated wheel load on potholes constructed in concrete blocks. The 15

distresses observed in the manufactured potholes were very similar to field distresses 16

reported in the literature. The accelerated testing was successful in differentiating the 17

performance of emulsion and asphalt binder mixes. 18

19

Objectives and Scope 20 21

The objectives of the present study is to investigate the performance of frequently used 22

pothole patching materials used in winter season in Tennessee through both field survey 23

and laboratory tests. Pothole patchings using different materials were installed on 24

highways of Tennessee in winter for long term field survey. According to the distress 25

observed on the field patchings, laboratory tests were designed and conducted to evaluate 26

the field performance of patching materials. 27

28

FIELD PERFORMANCE SURVEY 29

30

Installation of Pothole Patching 31 32

Tennessee Department of Transportation (TDOT) generally uses throw and roll 33

procedure for temporary pothole repairs in winter. The patching materials used for winter 34

repair include a hot mixed asphalt (HMA) mixture, a cold dump mix and two cold bag 35

mixes (A and B). HMA is a plant mixed mixture and pave with a heater truck. The cold 36

dump mix is a stockpile cold mixed asphalt mixture produced with slow curing cutback 37

asphalt. The two cold bag mixes use single size fine aggregate and rapid curing cutback 38

asphalt. 39

65 pothole patchings were installed on six highway sections in east and middle 40

Tennessee, including I75, I640, SR111, SR96, SR71 and SR33. The number of patchings 41

using HMA, cold dump, cold bag A and B were 21, 11, 28 and 5, respectively. The 42

length, width and depth of each patching was measured and recorded. The latitude and 43

longitude coordinates of the field spots were recorded by a GPS for the following survey. 44

Photos inventory was also set up for each patching. The average depth of patching ranged 45



5

from 1 to 3 in. The area of potholes ranged from 0.1 to 50 ft2. Large area pothole was 1

usually originated from longitudinal cracking. 2

3

Distress of Patching 4 5

The most commonly encountered distress for pothole patching includes bleeding, dishing, 6

edge disintegration, missing patch, raveling, pushing/shoving and alligator cracking 7

(7)(9). The descriptions and causes of those distresses are summarized as follows: 8

Bleeding is the flushing of asphalt to the surface of the patch. It is usually caused 9

by insufficient voids or excessive binder in the mix. 10

Dishing and Pushing/shoving is the bowl shape and vertical/horizontal 11

movement the patch and usually results from instability of mixture and inadequate 12

compaction during construction. 13

Edge disintegration and missing patch occurs when the patch material loses its 14

adhesion to the pavement underneath or sides of the pothole. The lose materials 15

can be easily pulled off by traffic. They are the most commonly distress for 16

“throw and roll” method and are usually caused by insufficient compaction, poor 17

cohesion, debonding and alligator cracking 18

Raveling is the loss of aggregate from the surface of the patch. Raveling is caused 19

by stripping, poor cohesion, excessive fine aggregates and poor aggregate 20

interlock of the patch material. 21

Alligator Cracking is the “bottom-up” cracking caused by the freeze thaw cycles 22

and is a typical distress of pothole patching during winter. 23

24

The pothole patchings were visually rated in terms of different distress by 25

following the procedure recommended by Virginia DOT (7). The ratings ranged from 1 26

to 4, with 4 indicated the best condition and 1 indicated the poorest distress condition. 27

Usually, an overall rating is determined in order of the importance and weighting factors 28

of different distress. The overall rating of a patching can be determined by equation (1). 29

The weighting factors were determined based on discussions with pavement maintenance 30

engineers of Tennessee DOT. The weighting factors of edge disintegration and missing 31

patching are higher since they are the two main distress for throw and roll patching in 32

winter season. 33

34 35

(1) 36 lligator cracking 37

38

Performance of Pothole Patching 39 40

Field performance surveys were performed 1, 3 and 6 weeks, 3 and 6 months after the 41

installation. Figure 1 shows the typical deterioration of a “throw and roll” pothole patch. 42

It can be seen that the patching deteriorated fast due to the freeze-thaw cycles, missing 43

patching was the major distress. According to the 3 month field performance survey, 44

missing patch and alligator cracking due to deboning and freeze-thaw cycles are the most 45

commonly encountered distress of potholes in winter season. 46



6

1

(a) Installation, rating 4

(b) 1 week after, rating 2

(c) 3 weeks after, rating 1

(d) 6 weeks after (new patch), rating 4

FIGURE 1 Installation and field survey of a pothole 2

3

Figure 2 summarized the number of distress before and after patching. It can be seen that 4

about half of the potholes were caused by various cracking, especially alligator cracking. 5

According to the field performance survey, missing patch and alligator cracking due to 6

deboning and freeze-thaw cycles are the most commonly encountered distress of potholes 7

in winter season. 8

9

10 (a) Count of main distress before patching 11

12 (b) Count of mian distress after patching 13

14 FIGURE 2 Distress of pothole patchings 15

0 10 20 30 40

Alligator crack

Longitudinal & transverse crack

Wheel path longitudinal crack

No

0

10

20

30

40

50

60

70

1 week 3 weeks 6 weeks 3 months 6 months

No

. of

Pat

chin

gs

No

New

Missing patch

Edge disintegration

Dishing



7

Influence of factors on Patching Performance 1 2

Multiple linear regression method, as shown in equation (2) was used to analyze the 3

influence of different factors (Xi) on the performance ratings (Y) of potholes. Analyzed 4

factors include service time, material, the length, width and depth of potholes, annual 5

average daily traffic (AADT), speed limit and freeze times. The freeze times are the 6

number of days when the temperature was lower than the freezing point. The daily 7

temperatures recorded by the weather stations within 5 miles of the pothole locations 8

were collected from the National Climatic Data Center (NCDC) (12). The responses of 9

the regression model include performance ratings in terms of dishing, edge disintegration 10

and missing patch and the overall rating. 11

12

kkii XXX Y 110 (2) 13

14

Where, βi = Parameters estimate of factor Xi, is the magnitude and direction change in 15

response with each one-unit increase in predictor i. 16

ε = random error term. 17

18

The ordinal least square method was used to estimate the parameters. Table 1 19

shows the p-value of the F-test, which indicates the significance of each predictor by 20

testing the significant increase in explained variation by adding that predictor to the 21

reduced model. Factors with p-values lower than 0.05 were regarded as significant; 22

indicating the probability of getting this result by chance is less than 5%. It can be seen 23

that the most of the factors are significant except for the width for missing patch. The p-24

value of time for missing patch is slightly larger than 0.05 and was regarded as marginal 25

significant. 26

27

TABLE 1 Summary of p-value of the partial t-test for the factors 28

Factors Dishing Edge disintegration Missing patch Overall rating

Time (Weeks) 0.0364 <.0001 0.0998 0.0181

Material <.0001 <.0001 0.0007 <.0001

Longitudinal length (ft) <.0001 0.0192 <.0001 <.0001

Transverse width (ft) 0.001 0.0261 0.3652 0.0158

Depth (in.) <.0001 <.0001 <.0001 <.0001

AADT 0.0155 <.0001 0.0014 0.0006

Speed limit (mile/h) <.0001 <.0001 <.0001 <.0001

Freeze time 0.0153 0.0013 0.0001 0.0002

29

Figure 3 shows the influence of each predictor on the response. The middle lines 30

within the plots show how the response changes when changing the current value of an 31

individual factor. The dotted curve surrounding the prediction trace (for continuous 32

variables) and the context of an error bar (for categorical variables) show the 95% 33

confidence interval for the predicted values. It can be seen from Figure 5 that, severe 34

weather, indicated as freeze times, accelerated the failure of patchings. Vehicle speed and 35

traffic level also accelerated the deterioration of patching, which is mainly caused by the 36



8

higher abrasion, pushing and pulling effect of traveling wheels. In addition, potholes with 1

higher length or width and lower depth deteriorated faster. 2

The rating of dishing indicated the resistance to permanent deformation of 3

materials. HMA had the highest stability, followed by cold dump mix, cold bag A and B. 4

The two cold bag mixes use fine aggregate so that they could be used as cracking filling 5

materials. However, the resistance to deformation is compromised due to the weak 6

aggregate skeleton. The resistance to edge disintegration and missing patching were 7

mainly determined by the cohesion and adhesiveness of patching material. It can be seen 8

that HMA and Cold bag A had higher resistance to debonding while cold dump mix 9

performed the worst. Since edge disintegration and missing patching have high weighting 10

factors in the overall rating, the material rank in terms of the overall rating was similar 11

with that of the missing patch. 12

13

14 FIGURE 3 Influence of different factors on patching distress 15

16

LABORATORY TESTS 17

18

The quality of material is of great importance for a successful pothole repair. Some of the 19

desired properties of patching materials include workability, adhesiveness, cohesion, 20

durability, freeze-thaw resistance and storageability (7). The distresses observed in the 21

field performance survey include missing patch, edge disintegration, alligator cracking 22

and dishing. To investigate the resistance of patching materials to those distresses, four 23

laboratory tests were performed. Adhesiveness and cohesion tests were conducted to 24

evaluate the materials’ adhesiveness to original pavement and inner cohesion. Moisture 25

susceptibility including a freeze-thaw cycle was conducted to evaluate the freeze-thaw 26

resistance of patching materials. Loaded wheel test was tried to evaluate the resistance of 27

mixture to permanent deformation. 28

29

30



9

Adhesiveness Test 1 2

Adhesiveness is the bond between patching mixture, the underlying pavement, and the 3

sides of the pothole. Loss of adhesion usually causes edge disintegration and missing 4

patch, which were the two main distresses observed in the field survey. For the traditional 5

“throw-and -roll” pothole repair procedures, no tack coat is applied before patching. The 6

adhesiveness of the patching materials plays a vital role in the bond between patching 7

material and original pavement. It is important to test the adhesiveness of different 8

patching materials become very important. 9

Several laboratory tests have been tried in an effort to produce a suitable 10

procedure to evaluate the adhesiveness of patching materials. Shear test was conducted to 11

evaluate the bonding strength of patching materials with old pavement but the results 12

were inconclusive (13)(7). In this study, a test procedure used by Virginia DOT for 13

quality control of cold patching material was adopted (7). 500 g lose mixtures were 14

placed in a 100-mm diameter Marshall mold on top of a 75-mm sample of compacted 15

HMA and compacted with 10 blows of a standard Marshall hammer. The compacted 16

sample is extruded and the sample is inverted. The adhesion of the mixture is measured 17

by the amount of time it takes for the specimen to drop from the substrate asphalt. Two 18

groups of materials were tested, the original and oven-aged at 60°C for 4 hr. The test was 19

conducted at room temperature (25°C). Figure 2 shows the testing procedure. 20

21

Cohesion Test 22 23

Cohesion test, also named rolling sieve test, measures the cohesion or the bonding inside 24

the materials. It was developed by the Ontario Ministry of Transportation to evaluate the 25

cohesion and durability of stockpiled patching materials and then revised by AASHTO 26

TP-44-94 (7)(8)(14). In this study, sealed loose cold mixes and the Marshall mold were 27

put in a refrigerator at 4°C for 12 hours. 1000 g cold-mix was then put in the mold and 28

compacted 5 times on each side with the Marshall hammer. The extruded sample was 29

placed in a 30.5 cm diameter full height sieve with 25.4 mm (1 in.) openings. A cover 30

was placed on the sieve and the sieve is rolled back and forth on its side approximately 31

550 mm (22 in) for 20 cycles. Recommended test times for this test is approximately 20 32

seconds (Tam and Lynch 1987). The sieve remained in this position for ten seconds to let 33

the lose material drop down. Then, the material loss is calculated by weighing the 34

material retained on the sieve. The percentage of materials retained on the sieve was 35

calculated as a measure of cohesion of the mixture. A higher percentage indicates a more 36

cohesive material. The Ontario Ministry of Transportation recommended a minimum 37

percentage retained of 60% for adequate cohesion in a cold-mix. One limitation of this 38

test is that it only indicates the cohesion at low temperature. The pavement surface 39

temperature could be much higher than 4°C direct sunlight even in winter. Thus, the test 40

was performed at room temperature (25°C) with different compaction times to investigate 41

the cohesion at moderate temperature. 42

43

44

45



10

Moisture Susceptibility Test 1 2

For all the patching materials used in the winter season pothole repair, freeze-thaw 3

cycling is the main cause of many distresses including alligator cracking missing patch 4

and edge-disintegration. Field survey indicated that the potholes at mountain area 5

deteriorated much faster due to the more severe freeze-thaw condition. Freeze-thaw 6

resistance, which is the capability of the patching mixture to withstand the expansion of 7

ice resulting from freeze-thaw cycles, plays a vital role in the durability of patching 8

mixture. 9

According to ASTM D4867, moisture susceptibility test with a freeze-thaw 10

cycling was conducted to evaluate the freeze-thaw resistance of patching materials. The 11

fresh loose cold mix using cutback asphalt could not be compacted into specimens. In 12

order to add stability to the mixture and simulate field conditions after several months of 13

traffic, the cold mixtures were cured and aged before compaction in an oven at 60°C for 14

96 hours (9). After curing, the cold and hot mixes were heated to 100°C and 135°C 15

respectively to prepare 100-mm diameter Marshall specimens. For moisture susceptibility 16

test, specimens are usually compacted to a void content between 6 to 8 %. However, due 17

to the lack of fine aggregate in the cold mix materials, the void content of cold bag A and 18

cold dump could not be controlled at 6% to 8% even with more compaction times. 19

Previous studies found that some cold mix patching material can have 10% air content 20

even with 200 gyration times (9). To simulate the actual compaction of repeated wheel 21

loads in the field, specimens were all compacted for 50 blows on each side. The air 22

content of cold dump, cold bag A, cold bag B and HMA are 10.5%, 13.5%, 4.1%, and 23

0.95%, respectively. The saturations were controlled between 70% and 80% as 24

recommended by ASTM D4867. 25

The partially saturated specimens were then wrapped with two layers of plastic 26

film, sealed into a leak-proof plastic bag, placed into a freezer at −7°C for 20 h and then 27

eventually immersed in a water bath at 60 °C for 24 h. During the test, the cold dump and 28

cold bag A specimens could not withstand the 60 °C water bath and collapsed after being 29

submerged in the hot water for 10 minutes. The low high temperature stability was 30

probably caused by the high air void and low viscosity. The air voids of cold dump and 31

Cold bag A were 10.5% and 13.5%m respectively, much higher than those of cold bag B 32

and HMA. At similar saturation level, specimens with higher air voids had higher void 33

pressure generated by the expansion of water in the freeze-thaw cycle. Even after curing 34

at 60°C for 96 hours, the viscosity of these cutback asphalt cold mixes might be still 35

lower than that of the traditional HMA and the low viscosity and cohesion caused 36

insufficient strength of the specimen. It seemed the traditional 60°C did not apply for 37

these cold patching mixtures. In addition, the pavement surface temperature in winter 38

season in Tennessee is not likely to be as high as 60 °C. In the revised procedure, the 39

water bath was changed to 25°C. 40

A MTS machine was utilized to test the indirect tensile strength (IDT) of both dry 41

and conditioned specimens. The indirect tensile strength (IDT) and tensile strength ratio 42

(TSR) can be calculated by using equation (1) and (2). 43

44

)(/2 psitDPSt (3) 45

46



11

Where, St = tensile strength (psi); 1

P = maximum load (lbf); 2

t = specimen height immediately before tensile test (in.); 3

D = specimen diameter (in.). 4

5

100)/( tdtm SSTSR (4) 6

7

Where, TSR = tensile strength ratio (%); 8

Stm = average tensile strength of the moisture conditioned subset (psi); 9

Std = average tensile strength of the dry subset (psi). 10

11

12

Loaded Wheel Test 13 14

In this study, Asphalt Pavement Analyzer (APA), a widely used loaded wheel tester, was 15

utilized to test the rutting resistance of mixture. As shown in Figure 4, the Hamburg test 16

procedure was adopted. A simulated pothole was made by putting two 150mm (6in.) 17

diameter and 38mm (1.5 in.) thick concrete pills at the bottom of the mold. The concrete 18

pill was fabricated by pouring 1.72 kg concrete into the 150mm (6in.) diameter and 19

300mm (12 in.) The rough surface of the pills faced up to simulate the actual rough 20

pothole bottom. Since the stiffness of the concrete base is much higher than that of 21

asphalt mixture, it doesn’t influence measured rutting depth. The volume for the asphalt 22

mixture left in the mold is around 828cm3. Loose were cured in an oven at 60°C for 96 23

hours first. After curing, 1800 g materials was heated to 100 °C, placed into the mold 24

and compacted with 30 blows of a standard Marshall hammer on each side. The 25

estimated air voids of the mixture were around 10%. The Hamburg wheel (8”in. diameter 26

and 1.85” in. width) was used in this test. The vertical load on each wheel was 158 lbs. 27

The test frequency was 1 Hz (one cycle per second) and test temperature was 25°C. 28

29

(a) Simulated Pothole

(b) Test device

Cold dump Cold bag B

(c) Specimens after test

30

Figure 4 Loaded wheel test device and simulated pothole 31

32

33



12

DISCUSSION OF LABORATORY TEST RESULTS 1

2

Adhesiveness Test 3 4

Figure 5 shows the adhesion time and weight of remnant of the adhesiveness test. HMA 5

had much higher adhesion time than cold mixes even with only one blow. Increasing 6

compaction greatly improved the adhesiveness of materials. Cured cold mixes had much 7

higher adhesiveness than the original cold mixes, since high temperature accelerated the 8

volatilization of the dilution in the mixture. High weight of remnant also indicates high 9

adhesiveness or inner-bonding of the material. For cured cold mixes, the ranking in terms 10

of the weight of remnant is the same with that of the adhesion time. 11

Previous researchers recommended 5 to 30 seconds as the optimum adhesion time 12

for cured cold mix (7). They pointed out that times less than 5 seconds may indicate 13

excessive binder contents; and times in excess of 30 seconds may indicate insufficient 14

binder content or an excessive stiff binder. The adhesion time of cured cold bag mixes 15

were between 20 to 30 seconds whereas that of cured cold dump mix was around 50 16

seconds. The cold dump seemed have insufficient binder content or excessive stiff binder, 17

which probably caused its poor performance regarding the edge integration and missing 18

patch in the field. 19

20

(a) Adhesion time

(b) Weights of remnant

21

Figure 5 Results of adhesiveness test 22

23

Cohesion Test 24 25

Figure 6 shows the cohesion test results, the percent of materials retained on the 25mm 26

size sieve. Generally, cold bag B had the highest percent of material retained, followed 27

by cold bag A and cold dump. At the standard test condition (4°C and 5 blows), the 28

percent of materials retained of the three cold mixes were all higher than the 29

recommended 60%, indicating sufficient cohesion. At 25°C test temperature, the 30

cohesion increased as the increase of compaction times. 31

The tested specimens can be classified into good, moderate and poor conditions. 32

The good specimen had little materials loss. The moderate specimen had moderate 33

material loss but still maintain its geometry shape. The poor specimen totally fell apart 34

0

10

20

30

40

50

60

70

Original Cured

Ad

he

sio

n ti

me

(Se

con

d)

Cold DumpCold bag ACold bag BHMA 1 blowHMA 2 blows

0

50

100

150

200

250

Original Cured

We

igh

t of R

em

nan

t (g)

Cold DumpCold bag ACold bag BHMA 1 blowHMA 2 blows



13

during the test and usually had percent of material retained lower than 60%. During the 1

test, cold dump and cold bag A specimens tested at 25°C and 5 blows were classified as 2

poor after testing. The test generating poor specimens could not differentiate different 3

materials if more than one group of material was in poor condition. A practical test 4

procedure should avoid having poor tested specimens. The 25°C with 15 blows test 5

conditions is recommended as an alternative to evaluate the cohesion of mixtures at 6

moderate temperature. 7

8

9 Figure 6 Results of cohesion test 10

11

Moisture Susceptibility Test 12 13

Figure 7 shows the indirect tensile strength of mixtures before and after the freeze-thaw 14

cycle and the TSR. HMA had highest indirect tensile strength among the three cold 15

mixed, followed by cold bag A, cold dump and cold bag B, which generally agreed with 16

the ranking of field performance rating for dishing distress. The low strength stability of 17

cold bag B is the main cause of its poor resistance to permanent deformation in the field. 18

The strength level of HMA was at least 4 times higher than those cold mixes, indicating 19

that it has the best stability with sufficient compaction. Although cold bag B had lowest 20

tensile strength, its TSR was higher than 1. HMA had TSR higher than 80%. The TSR of 21

cold dump and cold bag A were lower than 80%, which was mainly caused by the high 22

air voids of the specimen. 23

24

(a) Indirect tensile strength

(b) TSR

Figure 7 Results of moisture susceptibility test 25

0%

20%

40%

60%

80%

100%

4°C 5 blows 25°C 5 blows 25°C 10 blows 25°C 15 blows

Mat

eial

ret

aine

d (%

)

Cold DumpCold bag ACold bag B

0

30

60

90

120

150

Before After

Ind

ire

ct T

en

sile

Str

en

gth

(psi

) Cold DumpCold bag ACold bag BHMA

0.740.7

1.3

0.86

0%

20%

40%

60%

80%

100%

120%

140%

Cold Dump Cold bag A Cold bag B HMA

TSR



14

Loaded Wheel Test 1 2

During the loaded wheel test, the rutting depth of cold bag B reached 14 mm after around 3

200 load cycles and the test stopped. Tested specimens were shown in Figure 4. Because 4

of coarser gradation and tight aggregate interlock, the cold dump mixture exhibited better 5

rutting resistance. However, its rutting depth was still very high at such a low load cycles 6

comparing with traditional HMA mixture. Chatterje et al. also acknowledged that the 7

Hamburg stability testing was unstable for uncured materials or at temperatures greater 8

than 25 °C (77°F) regardless of the curing time (9). There are mainly two reasons for the 9

high deformation. Firstly, the laboratory compaction of the simulated pothole is 10

insufficient to simulate the tire compaction on the field. Secondly, the gradation of cold 11

bag B is very fine and does not provide a good skeleton for deformation resistance. Both 12

the two cold bag mixes use single size fine aggregate so that they can also be used as 13

cracking filling materials. However, their resistance to permanent deformation is highly 14

compromised. The traditional loaded wheel test doesn’t apply for such cold mixes. 15

Reduced wheel load is recommended for future study. 16

17

CONCLUSIONS AND FUTURE RESEARCH 18

19

This study evaluated the performance of patching materials used in winter season in 20

Tennessee through field survey and laboratory tests. The laboratory tests were conducted 21

to characterize the material properties that are critical for the desired field performance. 22

Base on findings of field survey and laboratory tests, some conclusions can be 23

summarized as follows: 24

25

1. Six month field survey indicated that edge disintegration and missing patch were 26

the two main distresses of throw and roll patchings in winter season. In addition 27

to service time and material, freeze condition, vehicle speed, traffic level, and the 28

size and depth of potholes are significant for the performance of patching. Severe 29

freeze condition, high traffic level and vehicle speed accelerated the deterioration 30

of patching. Patchings with lower depth and larger size especially longer 31

longitudinal length deteriorated faster due to the increased abrasion. 32

2. In terms of the overall rating in the field, HMA performed the best followed by 33

the two cold bag mixes and the cold dump. The cold dump mix showed high 34

potential to edge disintegration and missing patch, which is probably due to the 35

insufficient binder content or an excessive stiff binder, as indicated in the 36

laboratory adhesiveness test. The cold bag mixes exhibited weak resistance to 37

permanent deformation, which is caused the weak aggregate skeleton and low 38

strength performance as indicated in the laboratory indirect tensile strength test. 39

3. Laboratory tests showed that HMA mixture had higher adhesiveness and strength 40

than all the three cold mixes. Improve compaction could greatly increase both 41

adhesiveness and cohesion of patching mixes. 42

4. Cohesion test conducted at different temperature and compaction times presented 43

consistent ranking of materials. 25°C and 15 blows was recommended to evaluate 44

the cohesion of materials at moderate temperature. 45

46



15

5. The cold dump and cold bag A did not withstand the 60°C water bath in the 1

freeze-thaw cycling due to the high air void in the specimen. 25°C was 2

recommended instead of 60°C water bath in the freeze-thaw cycling for moisture 3

susceptibility test. The TSR of cold dump and cold bag A were between 60% and 4

80% which were mainly caused by the high air voids. The air voids of cold dump 5

and cold bag were higher than 10% with regular compaction effort because their 6

aggregate were of single size and could not form a dense gradation. 7

6. Loaded wheel test results showed that the cold bag mix using fine aggregate 8

exhibited high dishing and pushing potential due to the weak aggregate skeleton. 9

Traditional loaded wheel test procedure does not apply to the cold patching 10

material. Reduced wheel load and improved compacted specimens are 11

recommended to improve the effectiveness of the test. 12

13

Future research will primarily focus on improving the effectiveness of loaded 14

wheel test on differentiate the fine grade cold mixes. It is recommended to modify the test 15

method to evaluate the rutting resistance of cold mix, including reducing the wheel load 16

level and improving the compaction of specimens. With more field survey data collected, 17

long-term cost-effectiveness will be investigated by including the cost factor into 18

performance evaluation. 19

20

ACKNOWLEDGEMENT 21

22

The funding of this study was supported by the Tennessee Department of Transportation 23

(TDOT). The TDOT maintenance engineers are acknowledged for their assistance on 24

field patching installation. The contents of this paper reflect the views of the authors, who 25

are responsible for the facts and the accuracy of the data presented herein, and do not 26

necessarily reflect the official views or policies of the TDOT, nor do the contents 27

constitute a standard, specification, or regulation. 28

29

REFERENCE 30

31

1. Miller, J. S. and W. Y. Bellinger. Distress Identification Manual for the Long-Term 32

Pavement Performance Program (Fourth Revised Edition), Report no. FHWA-RD-33

03-031, Federal Highway Administration, 2003. 34

2. Wilson, T. P. and A. R. Romine. Materials and Procedures for Repair of Potholes in 35

Asphalt Surfaced Pavements - Manual of Practice, Report no. SHRP H348, 1993. 36

3. Thomax, H. R. and D. A. Anderson Pothole repair: you can't afford not to do it right. 37

Transportation Research Record: Journal of Transportation Research Board, No. 38

1102, TRB, National Research Council, Washington, D.C., 1986, pp 32-40. 39

4. Wilson, T. P. and A. R. Romine. Pavement Surface Repair Materials and 40

Procedures: Training Program - Pothole Repair. Report no. SS-20, Strategic 41

Highway Research Program, 1994. 42

5. Wilson, T. P. and A. R. Romine. Innovative Materials Development and Testing 43

Volume 2: Pothole Repair, Strategic Highway Research Program, Report no. SHRP-44

H-353, 1993. 45



16

6. Wilson, T. P. and A. R. Romine. Materials and Procedures for Repair of Potholes in 1

Asphalt Surfaced Pavements - Manual of Practice, Report no. FHWA-RD-99-168, 2

Federal Highway Administration, Washington, D.C. , 1999. 3

7. Prowell, B. D. and A. G. Franklin. Evaluation of Cold Mixes for Winter Pothole 4

Repair, Transportation Research Record, No. 1529, TRB, National Research Council, 5

Washington, D.C., 1996, pp76-85. 6

8. Maher, A., N. Gucunski, W. Yanko and F. Petsi. Evaluation of Pothole Patching 7

Materials, Report no. FHWA 2001-02, New Jersey Department of Transportation, 8

Federal Highway Administration, Washington, D.C. , 2001. 9

9. Chatterjee, S., R. P. White, A. Smit, J. Prozzi, and J. A. Prozzi. Development of mix 10

design and testing procedures for cold patching mixtures, Report no. FHWA/TX-11

05/0-4872-1, Texas Department of Transportation, Federal Highway Administration, 12

Washington, D.C. , 2006. 13

10. Rosales, V. I., J. Prozzi and J. A. Prozzi. Mixture Design and Performance-Based 14

Specifications for Cold Patching Mixtures. Report no. FHWA/TX-08/0-4872-2, 15

Texas Department of Transportation, Federal Highway Administration, Washington, 16

D.C. , 2007. 17

11. Fragachan, J. M. Accelerated Testing Methodology for Evaluating Pavement 18

Patching Materials, Thesis for master's degree, Worcester Polytechnic Institute, 19

2008. 20

12. National Climatic Data Center, National Oceanic and Atmospheric Administration. 21

http://gis.ncdc.noaa.gov/map/cdo/. Accessed July 6, 2012. 22

13. Anderson, D. A., H. R. Thomas, Z. Siddiqui, and D. Krivohlavek. More Effective 23

Cold, Wet-Weather Patching Materials for Asphalt Pavements, Report no. FHWA-24

RD-88-001. Federal Highway Administration, Washington, D.C. , 1988. 25

14. Tam, K. K., and D. F. Lynch. New Methods for Testing Workability and Cohesion of 26

Cold Patching Materials, Ontario Ministry of Transportation, Engineering Materials 27

Office, Bituminous Section, 1987. 28


field and laboratory evaluation of winter season pavement

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