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Technical Guide for the Pavement Preventive Maintenance

  • Feng LiEmail author
  • Jinyan Feng
  • Youxin Li
  • Siqi Zhou
Chapter
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Part of the Springer Tracts on Transportation and Traffic book series (STTT, volume 16)

Abstract

The preventive maintenance technical guide is a guideline and normative document for the preventive maintenance of asphalt pavement. It can improve the level of maintenance technology of asphalt pavement, so as to maintain and improve the performance of pavement, extend the overhaul period of the pavement, and reduce the life cycle maintenance of the pavement. Cost. The technical guidelines in this chapter include general principles, terms and symbols, pavement maintenance expectations, preventive maintenance decisions, post-assessment evaluation of preventive maintenance effects, and cycle life cost-benefit analysis.

Keywords

Preventive maintenance Pavement maintenance expectations Preventive maintenance decisions Post-assessment of preventive maintenance effects Cycle-life cost-benefit analysis 

2.1 General Provisions

2.1.1 Purpose

In order to standardize and guide the preventive maintenance of asphalt pavement, improve the maintenance technology of asphalt pavement, maintain and improve the performance of pavement, prolong the overhaul period of pavement, and reduce the maintenance cost of the whole life cycle of pavement, this guide is formulated.

2.1.2 Limitation

This guideline is suitable for preventive maintenance of asphalt pavement of expressway, First, Second and Third-Class Highway. Other roads can use this guide for reference.

2.2 Terms and Symbols

2.2.1 Pavement Preventive Maintenance

Pavement Preventive Maintenance is a pavement maintenance measure that does not disturb the pavement structure and does not change the strength of the pavement structure on the pavement without damage or only signs of minor diseases and diseases, which is for the sake of improving the whole maintenance benefit in cycle of pavement, preventing the occurrence of pavement diseases or the further expansion of minor diseases, delaying the attenuation of pavement performance, and maintaining and improving pavement performance.

2.2.2 Maintenance Benefit in Cycle

According to the pavement preventive maintenance mode, Maintenance Benefit in Cycle is the economic and social benefits generated by the pavement preventive maintenance during the period between new construction and overhaul or two overhauls of pavement.

2.2.3 Maintenance Cost in Cycle

According to the preventive maintenance mode, Maintenance Cost in Cycle is the maintenance costs that occur during the period between new construction and overhaul or two overhauls of the pavement.

2.2.4 Optimal Time of PPM

During the period from new construction to overhaul or two overhauls, the Optimal Time of PPM is the preventive maintenance implementation time point with the maximum benefit-cost ratio can be obtained.

2.2.5 Crack Filling and Sealing

Crack Filling and Sealing is a technique of filling cracks in asphalt pavement with special sealant.

2.2.6 Crack Seal Band

Crack Seal Band is a technology of using a joint band to stick cracks in asphalt pavement.

2.2.7 Fog Seal

Fog Seal is a kind of pavement preventive maintenance technology, which sprays special fog seal material on the surface of asphalt pavement, closes some micro-cracks and voids of asphalt pavement, plays a waterproof role, prevents further aging of pavement, and improves the appearance of pavement.

2.2.8 Sand Fog Seal

Sand Fog Seal refers to the original fog seal material mixed with adding clay, clay and other fillers, which improves the anti-slip performance and wear resistance of the fog seal.

2.2.9 Mastic Seal

It is a pavement preventive maintenance technology which uses special modified emulsified asphalt and fine aggregate to evenly spray or scrape to the surface of asphalt pavement, seal the micro cracks and pores of asphalt pavement, stabilize the loose aggregate on the surface of old pavement, improve the waterproof performance of old pavement and slow down the aging rate of pavement.

2.2.10 Slurry Seal

Slurry Seal is a thin layer technology that uses special mechanical equipment to spread emulsified asphalt, coarse and fine aggregates, fillers, water, and additives into slurry mixture on the original pavement according to the design ratio.

2.2.11 Micro-surfacing

Micro-surfacing is a thin layer technology with high skid resistance and durability, which uses special mechanical equipment to spread polymer modified emulsified asphalt, coarse and fine aggregates, fillers, water and additives into slurry mixture according to the design ratio on the original pavement, and quickly restores the traffic.

2.2.12 Chip Seal

Chip Seal is a technology that uses aggregates of near single particle size and asphalt binder that meets the requirements in accordance with the laying method.

2.2.13 Fiber Seal

Fiber Seal is a technology that uses Construction Equipment for Synchronized Fiber Seal, spraying two layers of asphalt binder and one layer of glass fiber at the same time, then spreading gravel on it, and forming a new wearing surface or stress absorbing membrane interlayer (SAMI) after rolling.

2.2.14 Thin Overlay

Thin Overlay is an asphalt overlay technology with a thickness of 30 mm (+5 mm) on the original asphalt pavement.

2.2.15 Ultra-Thin Overlay

Ultra-thin Overlay is an asphalt overlay technology with a thickness of 20 mm (+5 mm) on the original asphalt pavement.

2.2.16 In-Place Hot Recycling for Asphalt Pavement Surface

In-place Hot Recycling for Asphalt Pavement Surface is a technology of regenerating old asphalt pavement in the range of 20–30 mm by using special in situ thermal regeneration equipment, heating and loosening asphalt pavement, mixing a certain amount of new asphalt, new aggregates, new asphalt mixture or regeneration agent in situ, and through hot mixing, paving, rolling and other processes.

2.2.17 Symbols

Symbols used in this guide and their meanings are listed in Table 2.1.
Table 2.1

Symbols and their meanings

Number

Symbols

Meanings

2.2.1

PPM

Pavement preventive maintenance

2.2.2

AADT

Annual average daily traffic

2.2.3

PQI

Pavement quality index

2.2.4

PCI

Pavement condition index

2.2.5

RQI

Road quality index

2.2.6

RDI

Rutting depth index

2.2.7

SRI

Sliding resistance index

2.2.8

PSSI

Pavement structural strength index

2.2.9

IRI

International roughness index

2.2.10

PBI

Preventive benefit index

2.2.11

EUAC

Equivalent uniform annual cost

2.2.12

BCR

Benefit-cost ratio

2.2.13

EAC

Equivalent annual cost

2.3 Expectation Level of Pavement Maintenance

2.3.1 Evaluation Index of Pavement Technical Conditions

The evaluation of asphalt pavement technical condition is expressed by Pavement Quality Index (PQI) and Pavement Condition Index (PCI), Road Quality Index (RQI), Rutting Depth Index (RDI), Skid Resistance Index (SRI) and Pavement Structural Strength Index (PSSI). The range of PQI and corresponding sub-index is 1–100.

Asphalt pavement technology is divided into five grades: Excellent, Good, Medium, Secondary and Inferiority. The grade of technical condition of asphalt pavement is determined according to the standard specified in Table 2.2.
Table 2.2

Standard for evaluating the technical condition of asphalt pavement

Rating level

Excellent

Good

Medium

Secondary

Inferiority

PQI and sub-indicators at all levels

≥90

≥80, <90

≥70, <80

≥60, <70

<60

The performance index (PQI) of asphalt pavement is calculated by Formula (2.1).
$$ PQI = w_{PCI} PCI + w_{RQI} RQI + w_{RDI} RDI + w_{SRI} SRI $$
(2.1)

Formula:

wPCI—The weight of PCI in PQI is calculated in Table 2.3.
Table 2.3

Weight coefficient of PQI index of asphalt pavement

Evaluating indicator

Highway, first-class highway

Second and third-class highways

wPCI

0.35

0.60

wRQI

0.40

0.40

wRDI

0.15

wSRI

0.10

wRQI—The weight of RQI in PQI is calculated in Table 2.3.

wRDI—The weight of RDI in PQI is calculated in Table 2.3.

wSRI—The weight of SRI in PQI is calculated in Table 2.3.

2.3.2 Evaluation Index of Technical Condition of Urban Road Surface

The evaluation contents of urban road technical condition include road driving quality, road damage condition, road structure strength, road anti-sliding ability and comprehensive evaluation. The corresponding evaluation indexes are Road Quality Index (RQI), Pavement Condition Index (PCI), Rebound Deflection Value of Road Surface, Anti-sliding Coefficient (BPN or SFC) and Pavement Quality Index (PQI).

The technical conditions of urban road pavement are divided into four grades: A, B, C and D. The technical condition grade of urban road pavement shall be determined according to the standards specified in Table 2.4.
Table 2.4

Evaluation standard for technical condition of urban road surface

Evaluating indicator

A

B

Expressway

Artery road and secondary artery road

Branch road

Expressway

Artery road and secondary artery road

Branch road

PQI

≥90

≥85

≥80

≥75, <90

≥70, <85

≥65, <80

Evaluating indicator

C

D

Expressway

Artery road and secondary artery road

Branch road

Expressway

Artery road and secondary artery road

Branch road

PQI

≥65, <75

≥60, <70

≥60, <65

<65

<60

<60

Pavement Quality Index (PQI) of Urban road pavement is calculated according to Formula (2.2)
$$ PQI = T \times \omega_{1} \times RQI + PCI \times \omega_{2} $$
(2.2)

Formula:

PQI—Pavement Quality Index, the value range is 0–100;

T—RQI score conversion coefficient, T is 20;

ω1, ω2—is the weight of RQI and PCI respectively; for expressway or trunk road, ω1 is 0.6, ω2 is 0.4; for the secondary artery road or branch road, ω1 is 0.4, ω2 is 0.6.

Pavement Quality Index (PQI), Pavement Condition Index (PCI), Road Quality Index (RQI) and Rutting Depth Index (RDI) should meet the requirements of Table 2.5.
Table 2.5

Asphalt pavement maintenance expectation level

Highway grade

PCI

RQI

RDI

Expressway

≥95

≥95

≥95

First-class highway

≥93

≥93

≥93

Second-class highway

≥90

≥90

Third-class highway

≥90

≥85

2.4 Preventive Maintenance Decision

2.4.1 General Provisions

For the roads that need the preventive maintenance, depending on the different maintenance objectives, Crack Sealing, Crack Seal Band, Fog Seal, Chip Seal, Fiber Seal, Slurry Seal, Micro-surfacing, Thin Overlay, Ultra-thin Overlay, In-place Hot Recycling for Asphalt Pavement Surface and other technologies are selected for preventive maintenance.

Taking 1 km road section as a unit, preventive maintenance decision-making is made taking into account traffic volume, road age, main maintenance objectives, original pavement technical status, maintenance funds, and other factors.

The basic requirement of preventive maintenance for road conditions is that the strength of pavement structure meets the requirement, the condition of pavement is good and the pavement is relatively flat.

Pavement adopting preventive maintenance measures should conform to the corresponding macro and micro road condition standards for preventive maintenance.

Before preventive maintenance, the local diseases of the original pavement should be pretreated.

2.4.2 Evaluation Criteria for Road Conditions Suitable for Preventive Maintenance

PSSI and PCI are two indicators for judging the appropriate road condition for preventive maintenance. Among them, PSSI is the test index and PCI is the judgment index. That is, on the premise that PSSI meets the requirements, PCI is used as the criterion to judge whether the pavement needs preventive maintenance.

The macro-technical conditions of pavement suitable for preventive maintenance are pavement structural strength PSSI (>85), pavement damage index PCI (>85), as shown in Table 2.6.
Table 2.6

Comprehensive indicators for preventive maintenance

Road grade

Expressway, first class highway

Second and third class highway

PSSI

≥90

≥85

PCI

≥90

≥85

When the function of water sealing and anti-skid of the original pavement is insufficient, the appropriate technology can be selected for preventive maintenance of the pavement.

On the premise that the macro road condition standard meets the requirement of preventive maintenance, it is necessary to judge whether the individual index meets the micro road condition standard of preventive maintenance.
  1. 1.

    Transverse crack and longitudinal crack belong to a slight degree;

     
  2. 2.

    Rutting depth less than 15 mm;

     
  3. 3.

    Surface irregularities such as overcrowding and subsidence are mild.

     
When there are one or more of the following conditions in the local pavement, the disease should be pre-treated before preventive maintenance to meet the Micro-condition standard of preventive maintenance.
  1. 1.

    Pavement with moderate or more cracks;

     
  2. 2.

    There are serious transverse cracks and longitudinal cracks in the pavement (crack width exceeds 3 mm);

     
  3. 3.

    Rutting due to instability of asphalt concrete;

     
  4. 4.

    There are some serious phenomena on the surface of asphalt concrete pavement, such as overcrowding and pushing;

     
  5. 5.

    Poor subgrade condition;

     
  6. 6.

    Poor drainage conditions or humidity-related damage of pavement.

     

2.4.3 Appropriate Time of the Pavement Preventive Maintenance

When the relevant data are sufficient, the optimal preventive maintenance time is determined according to the process shown in Fig. 2.1.
Fig. 2.1

The process of determining the optimal preventive maintenance time

For preventive maintenance mode, the preventive maintenance time can be determined according to the technical condition, referring to Table 2.7.
Table 2.7

Recommended time for application of preventive maintenance measures

Measures

Crack sealing/crack seal band

Fog seal/sand fog seal/mastic seal

Chip seal/fiber seal

Slurry seal/micro-surfacing

Thin overlay/ultra-thin overlay/in-place hot recycling for asphalt pavement surface

Time (year)

Immediate

2–3

3–5

3–5

3–6

Note The time in this table refers to the opening time after new construction, last overhaul or preventive maintenance of the pavement

2.4.4 Cost-Benefit Analysis of Maintenance Countermeasures

The unit cost of pavement preventive maintenance measures is determined according to the cost of immediate materials and construction.

The service life of preventive maintenance measures can be determined according to practical experience, which can be determined with reference to Table 2.8.
Table 2.8

Service life of preventive maintenance measures

Type

Life expectancy (year)

Crack sealing/crack seal band

2–4

Fog seal/sand fog seal/mastic seal

1–2

Chip seal/fiber seal

3–4

Slurry seal/micro-surfacing

3–5

Thin overlay/ultra-thin overlay/in-place hot recycling for asphalt pavement surface

4–5

Equivalent Annual Cost method (EAC) is widely used because of its simplicity. The calculation equation is as follows:
$$ {\text{EAC}} = {\text{unit}}\,{\text{cost}}/{\text{life}}\,{\text{expectancy}} $$

On the basis of cost-benefit analysis, further analysis is needed for specific projects, considering construction, climate, and other factors comprehensively.

The PCI decay equation of conventional maintenance is determined, and the suitable time range for preventive maintenance is determined by the decay equation and preventive maintenance standard of PCI, and the preventive maintenance time comparison scheme is selected according to the same time interval or road maintenance plan.

Determine the decay equation of the road condition index of conventional maintenance and preventive maintenance time comparison schemes. For surface overlay preventive maintenance measures, PCI, RQI, and SRI should be included; for non-surface overlay preventive maintenance measures, only PCI can be selected as a road condition index.

For surface paving preventive measures, the area under PCI, RQI and SRI decay curves and the area under PCI, RQI and SRI decay curves of conventional maintenance were calculated respectively, and the preventive maintenance benefit index (PBI) was calculated; for non-surface paving preventive maintenance measures, the area under PCI, RQI, and SRI decay curves was calculated. The area under PCI decay curve increased by preventive maintenance relative to conventional maintenance is the preventive maintenance benefit index PBI.

Calculate the Equivalent Uniform Annual Cost (EUAC) of daily maintenance, preventive maintenance and intermediate repair of each time plan in the pavement life cycle.

Calculate the cost-benefit ratio of preventive maintenance of each time plan, and finally, take the time point corresponding to the time plan with the largest BCR value as the best time for preventive maintenance.

2.4.5 Selection of Preventive Maintenance Measures

The preventive maintenance engineering technology of pavement mainly includes Crack Sealing, Crack Seal Band, Fog Seal, Sand Fog Seal, Chip Seal, Fiber Seal, Slurry Seal, Micro-surfacing, Thin Overlay, Ultra-thin Overlay, In-place Hot Recycling for Asphalt Pavement Surface and so on. It encourages the popularization and application of new technology, new materials, new technology, and new equipment.

What preventive maintenance measures should be taken should be determined according to road conditions, traffic volume, funds, and cost-effectiveness. The specific application can refer to the measures recommended in Tables 2.9 and 2.10.
Table 2.9

Preventive maintenance measures applicable to all grades of roads

Road grade

Preventive maintenance measures

Crack sealing/crack seal band

Fog seal/sand fog seal/mastic seal

Chip seal/fiber seal

Slurry seal

Micro-surfacing

Thin overlay/ultra-thin overlay

In-place hot recycling for asphalt pavement surface

Express, first class highway

×

×

Second and third class highway

×

Note ★—recommend, ∆—prudent use, ×—not recommended

Table 2.10

Recommendation form for the application of preventive maintenance measures

Pavement leading damage types

Severity

Crack sealing/crack seal band

Fog seal/sand fog seal/mastic seal

Chip seal/fiber seal

Slurry seal

Micro-surfacing

Thin overlay/ultra-thin overlay/in-place hot recycling for asphalt pavement

Crack type

Crazing

Sight

×

×

Moderate

×

×

×

×

×

Severe

×

×

×

×

×

×

Massive cracks

Sight

×

×

Severe

×

×

×

×

×

×

Longitudinal crack

Sight

×

Severe

×

×

×

×

×

Transverse crack

Sight

×

Severe

×

×

×

×

×

Deformation class

Rutting

Sight

/

×

Severe

/

×

×

×

×

Loose class

Loose

Sight

/

Severe

/

×

×

×

×

Other classes

Pan oil

/

/

×

Polish

/

/

×

Pothole

Sight

/

×

×

×

×

×

Severe

/

×

×

×

×

×

Settlement

Sight

/

×

×

×

×

×

Severe

/

×

×

×

×

×

Other

Sealing water

/

/

Restoration of skid resistance

/

/

×

PCI

>90

/

85–90

/

<85

/

×

×

×

×

×

Traffic

Sight

/

Moderate

/

Severe

/

Particularly severe

/

×

×

Note ★—recommend, ∆—prudent use, ×—not recommended

2.5 Post-evaluation of Preventive Maintenance Effect

The post-evaluation mechanism of the preventive maintenance effect should be established, the road performance of preventive maintenance section should be tracked and observed, and the preventive maintenance effect of pavement should be summarized.

All the data of the pavement technical condition of preventive maintenance section should be collected, and the test basis is the relevant provisions of the industry standard of the People’s Republic of China, JTG E60.

The evaluation of pavement technical condition is expressed by pavement performance index PQI and corresponding sub-index. The calculation methods of each index shall be implemented in accordance with the provisions of the Industry Standard of the People’s Republic of China “Evaluation Standard for Highway Technical Conditions” (JTG H20).

PCI is the main evaluation index for the preventive maintenance effect of pavement, and the main basis is whether the actual road effect achieves the anticipated goal of preventive maintenance.

The preventive maintenance test road should be evaluated. If the preventive maintenance effect is not good, the lessons should be summarized, the reasons should be analyzed, and the preventive maintenance effect is good. The experience should be summarized and popularized.

2.6 Cost-Benefit Analysis of Life Cycle

2.6.1 Periodic Maintenance Costs

The cost items that need to be considered include daily maintenance fees, preventive maintenance fees, and repair fees. In the actual analysis, if there is no data, only one or several items can be selected, but the preventive maintenance fee must be included.

Because the maintenance period of each comparison scheme is different, the EUAC method is used to calculate the cost of each comparison scheme.

In calculating EUAC, for any preventive maintenance scheme j, the cost analysis period is selected [0, Xej] because the cost items considered are all in the period from the new construction or the latest major (medium) repair to the next mid-repair. The computational model of EUACj is shown in Fig. 2.2. According to the computational model, the computational process can be divided into the following two steps:
Fig. 2.2

Schematic diagram of a calculation model for EUACj

Step 1: Calculate the total present value of all maintenance costs during the cost analysis period and choose the time of new road construction or the latest major (medium) repair at zero point. The calculation formula is as follows:
$$ PW_{j} = \sum {C_{i} (1 + d)^{ - t} } $$
(2.3)

\( PW_{j} \)—The total present value of maintenance costs incurred by the jth preventive maintenance time plan during its cost analysis period;

\( C_{i} \)—A maintenance cost incurred in the future t-time;

\( d \)—Interest rate (e.g. 4%, d = 0.04) can be chosen according to the local economic development level;

\( t \)—The time (year) of future maintenance.

The second step is to convert the present value of each maintenance expense into the equivalent average annual cost (EUAC). The calculation formula is as follows:
$$ {EUAC}_{j} = PW_{j} \left[ {\frac{{d(1 + d)^{nj} }}{{(1 + d)^{nj} - 1}}} \right] $$
(2.4)

Among them:

\( EUAC_{j} \)—The equivalent average annual cost of the jth preventive maintenance program;

\( nj \)\( nj = X_{ej} \). The length of the cost analysis period of the jth preventive maintenance scheme.

2.6.2 Benefit Analysis

2.6.2.1 Benefits of Routine Maintenance

Conventional maintenance refers to the method of routine maintenance instead of preventive maintenance when the pavement is in good condition, until the condition of the pavement decreases to an unacceptable level. The benefits of conventional maintenance can be expressed by the area under the performance curve of the pavement. Benefit area of conventional maintenance refers to the area surrounded by the baseline (offline) calculated by the decay curve of each benefit analysis index and its benefit during the benefit analysis period.

2.6.2.2 Benefits of Preventive Maintenance

The benefit of preventive maintenance can be expressed by the area under the pavement performance curve increased by preventive maintenance relative to conventional maintenance. The benefit area of preventive maintenance refers to the area surrounded by the analysis index decay curve under conventional maintenance, the analysis index decay curve under preventive maintenance and the benefit calculation baseline during the benefit analysis period.

2.6.2.3 Standardization of Preventive Maintenance Benefits

The benefits of preventive maintenance are mainly manifested in the comprehensive improvement of PCI, RQI, and SRI after preventive maintenance of pavement. Therefore, the periodic maintenance benefit is characterized by the standardized preventive benefit of each benefits analysis index according to the weighted value of its weight coefficient, that is, the preventive benefit index. Abbreviated as PBI, the calculation formula is as follows:
$$ PBI_{j} = \gamma_{1} SB_{j} (PCI) + \gamma_{2} SB_{j} (RQI) + \gamma_{3} SB_{j} (SRI) $$
(2.5)

In the equation:

\( PBI_{j} \)—The preventive maintenance benefit index of any scheme j;

SBj (PCI)—Standardized benefits of PCI;

SBj (RQI)—Standardized benefits of RQI;

SBj (SRI)—Standardized benefits of SRI;

\( \gamma_{1} \), \( \gamma_{2} \) and \( \gamma_{3} \)—Benefit weight coefficients of PCI, RQI and SRI respectively.

Standardization benefits of PCI, RQI, and SRI are achieved by using the percentage of the benefit area of preventive maintenance to the benefits area of conventional maintenance, respectively, SBj (PCI), SBj (RQI) and SBj (SRI).

For example, for a preventive maintenance scheme j, the standardized benefits of PCI, SBj (PCI), can be calculated by the following formula:
$$ SB_{j} (PCI) = \frac{{A_{j} (PCI)}}{{A_{0} (PCI)}} $$
(2.6)

Formula:

\( A_{j} (PCI) \)—Preventive maintenance benefit area of PCI;

\( A_{0} (PCI) \)—The benefit area of routine maintenance of PCI.

2.6.3 Benefit-Cost Ratio

After calculating the preventive maintenance benefit index and its equivalent annual cost EUACj of any maintenance scheme according to the above method, the benefit-cost ratio can be further calculated.

As shown below. According to the cost-benefit method, the best maintenance scheme is the one with the highest benefit-cost ratio.
$$ BCR_{j} = \frac{{PBI_{j} }}{{EUAC_{j} }} $$
(2.7)

Formula:

\( BCR_{j} \)—The benefit-cost ratio of the jth preventive maintenance scheme;

\( PBI_{j} \)—The preventive maintenance benefit index of the jth preventive maintenance scheme;

\( EUAC_{j} \)—The equivalent annual cost of the jth preventive maintenance program.

Copyright information

© Springer Nature Singapore Pte Ltd. 2021

Authors and Affiliations

  1. 1.Beihang UniversityBeijingChina
  2. 2.Beihang UniversityBeijingChina
  3. 3.Beihang UniversityBeijingChina
  4. 4.Beihang UniversityBeijingChina

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