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CHAPTER FOUR
TECHNOLOGY OF PAVEMENT PRESERVATION TREATMENTS
This chapter describes the technology of pavement M&R ments are used across the country. For example, 84% of air-
treatments for AC and PCC pavements. It also describes the ports (that have AC pavements) reported that they routinely
survey results concerning the use and performance of M&R use crack sealing with hot-poured sealant (Table 3). Simi-
treatments reported by airport agencies. larly, 61% of agencies (that have PCC pavements) reported
that they are routinely using, or have tried using, joint seal-
ing with silicone sealant (Table 4).
SURVEY RESULTS
The use of some M&R treatments depends on the size and
Survey results for AC and PCC pavements are summarized
volume of traffic of the airport, such as the treatments aimed
in Tables 3 and 4, respectively. The tables contain informa-
at increasing pavement friction. Consequently, although about
tion on the usage and performance of common M&R treat-
ments as reported by 50 representatives of airport agencies. 39% of the responding airports reported using diamond grind-
There were 19 M&R treatments included in the survey for ing (routinely or on a trial basis), the percentage for small air-
AC pavements (Table 3) and 19 M&R treatments for PCC ports would probably be considerably lower, and for large
pavements (Table 4). The treatments traditionally considered airports most likely considerably higher.
to be preventive maintenance treatments are shown in Tables 3
and 4 in italic font. For AC pavements, the following six M&R treatments
were used by less than 15% of agencies that had AC pave-
Data presented in Tables 3 and 4 are the percentages of ments on at least one facility: spray patching, texturization
usage or performance of M&R treatments reported by survey using fine milling, microsurfacing, hot and cold in-place
respondents. For example, referring to the first row of data in recycling, and PCC overlay.
Table 3, 84% of airports that responded to the survey routinely
use crack sealing with hot-poured sealant and 11% of airports For PCC pavements, the following four M&R treatments
have tried using this treatment. Consequently, 95% of the air- were used by less than 15% of the agencies: load transfer
ports routinely use or have tried using this treatment and the restoration treatments using sub-sealing and slab stitching,
remaining 5% have not. Continuing with the example data in full-depth repairs using precast panels, and microsurfacing.
the first row, 19% of the airports that routinely use or have tried
using crack sealing with hot-poured sealant reported very good
Performance of Maintenance
performance with this treatment, 71% of the airports reported and Rehabilitation Treatments
good performance, and 10% of the airports reported poor per-
formance. The number of reporting airports, corresponding to Survey results concerning the performance of M&R treat-
the percentages of airports given in Tables 3 and 4, are pre- ments reported in Tables 3 and 4 are not reliable because of
sented in Appendix A as part of the Survey Questionnaire. sample size limitations and the lack of objective guidelines
for the evaluation of treatment performance. A very large
Approximately 70% of the responding airports had both sample size would be needed to obtain a statistically signifi-
AC and PCC pavements on at least some airfield facilities, cant number of performance reports for the M&R treatments
and about 30% of airports had both AC and PCC pavements that are not frequently used, even if all survey responses were
on runways (Figure 11). Approximately 50% of airports had grouped in one sample. However, the treatment performance
only AC pavements on runways and 20% of airports had only may depend on the environmental zone (e.g., wet-freeze,
PCC pavements on runways. Considering the distribution of dry-freeze, dry-no freeze, and wet-no freeze) and on the air-
pavement types, a large segment of airports need to have staff
port facility (runway, taxiway, and apron) further increasing
familiar with the technology of both AC and PCC pavements.
the sample size.
Use of Maintenance and Rehabilitation Treatments To obtain an objective rating of the treatment perfor-
mance shown in Tables 3 and 4 would also require the devel-
Information on the use of M&R treatments obtained from the opment of performance evaluation guidelines for all M&R
survey provides a good indication of what types of such treat- treatments and adherence to such guidelines by the respon-
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TABLE 3
PAVEMENT PRESERVATION TREATMENTS FOR ASPHALT
CONCRETE PAVEMENTS
Survey Result, %
Usage Performance
Treatment Type
Routine
Good
Good
Tried
Have
Total
Very
Poor
hot-poured sealant 84 11 95 19 71 10
Crack sealing with
cold-applied sealant 9 7 16 17 66 17
hot mix 52 16 68 42 58 0
Small area (pothole) cold mix 43 18 61 13 50 37
patching using
proprietary mix 9 11 20 25 50 25
Spray patching (includes manual chip seal) 5 7 11 0 100 0
Machine patching with AC 27 14 41 39 55 6
Milling and machine patching with AC 34 18 52 39 61 0
fine milling 7 5 11 20 80 0
Texturization using
controlled shot blasting 0 16 16 0 71 29
Rejuvenators, fog seals, etc. 30 23 52 23 59 18
Surface treatment 15 18 43 6 81 13
Slurry seal 23 25 48 10 75 15
Microsurfacing 2 9 11 25 75 0
Hot-mix overlay 45 23 68 48 48 4
Milling and hot-mix overlay 45 18 64 58 42 0
Hot in-place recycling 5 2 7 N/A N/A N/A
Cold in-place recycling 2 0 2 N/A N/A N/A
Whitetopping (PCC overlay) 7 7 14 60 20 20
Notes: Treatments traditionally considered preventive maintenance treatments are in italics.
N/A: sample size is too small.
dents. For example, evaluation guidelines would need to be routinely use or tried making shallow repairs of PCC slabs
prepared to explain what conditions need be met to rank the using PCC material or AC material. It is generally recom-
performance of an overlay as very good. Several respondents mended that PCC material be used to repair PCC slabs. This
did not provide performance ranking for treatments that they recommendation is supported by the performance data given
do not use routinely, and some respondents were reluctant to in Figure 12. As expected, the survey data show somewhat
provide any ranking at all. Nevertheless, the performance better performance of PCC material.
information obtained from the survey provides information
on overall trends. Innovative and Additional Treatments
Average performance data from the survey respondents In addition to the common M&R treatments listed in Tables 3
for both AC and PCC pavements are presented in Table 5. and 4, airport agencies reported the use, and in some cases
There is only a very small, statistically insignificant differ- commented on the performance, of the following innovative
ence between the average performance of M&R treatments M&R treatments:
for AC pavements and those for PCC pavements. For exam-
ple, on the average, the performance of approximately 60% · Stress-relieving membranes to retard reflective crack-
of M&R treatments for AC pavements was rated as good, ing in AC overlays.
whereas the corresponding number of M&R treatments for · Proprietary materials for AC overlays.
PCC pavements was about 58%. On average, only about · Portland cement with high proportions of fly ash and
11% of M&R treatments for AC pavements received a poor blast furnace slag.
performance, whereas the corresponding percentage for PCC · Rejuvenators (asphalt emulsions) to stabilize granular
pavements was 12. shoulders.
· Over-band method of sealing cracks in AC pavements
For frequently used treatments, it is possible to identify with sealing material containing fibers.
some expected trends in the performance of M&R treat- · Slurry seals containing thermoplastic coal-tar (fuel-
ments. For example, approximately 50% of airport agencies resistant) emulsion.
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TABLE 4
PAVEMENT PRESERVATION TREATMENTS FOR PORTLAND CEMENT
CONCRETE PAVEMENTS
Survey Result, %
Usage Performance
Treatment Type
Routine
Good
Good
Tried
Have
Total
Very
Poor
Joint/crack sealing bituminous sealant 29 15 44 13 80 7
with silicone sealant 39 22 61 29 71 0
neoprene seal 7 22 29 36 36 27
Load transfer restoration sub-sealing and slab
2 5 7 N/A N/A N/A
jacking
slab stitching 2 5 7 N/A N/A N/A
dowel retrofit 12 5 17 60 40 0
Shallow patch repair PCC 34 15 49 28 67 6
using AC 29 20 49 18 65 18
proprietary mix 17 17 34 42 42 17
Full and partial depth PCC 46 15 61 47 47 6
repairs or slab AC 20 39 59 31 54 15
replacement using
proprietary mix 7 17 24 30 50 20
precast panels 2 2 5 N/A N/A N/A
Machine patching with AC 5 12 17 33 50 17
Diamond grinding 5 34 39 21 79 0
Controlled shot blasting 0 15 15 0 80 20
Microsurfacing 0 5 5 N/A N/A N/A
AC overlay 10 27 37 36 64 0
Bonded PCC overlay (whitetopping) 7 7 15 40 40 20
Notes: Treatments traditionally considered preventive maintenance treatments are in italics.
N/A: sample size is too small.
· Fuel-resistant AC containing resin-modified asphalt
Only AC Only PCC AC & PCC
80 cement.
· Warm-mix AC (rather than the traditional hot mix).
Percentage of respondents
60 · Transverse grooving of AC pavement surfaces to improve
pavement friction.
· Specific repairs of wide or deteriorated pavement cracks
40
in AC pavements.
· Various types of fog seals.
20 · Crack filling AC mixes (mastic) for repairs of large
cracks in AC pavements.
0 · Proprietary AC and PCC mixes for patching repairs.
All facilities Runways only
Facility type
All of these M&R treatments and materials require continu-
FIGURE 11 Distribution of pavement types. ing evaluation to document cost-effectiveness.
TABLE 5
AVERAGE PERFORMANCE OF M&R TREATMENTS
FOR DIFFERENT PAVEMENT TYPES
Average Performance for all Treatments
No. No. and Airports (%)
of of
Pavement Type Airports Treatments Very Good Good Poor
AC Pavements 44 19 30.2 59.1 10.7
PCC Pavements 41 19 29.6 58.1 12.3
