microsurfacing paper issa world congress_english

7
7th ISSA World Congress, Lyon 2010 Micro surfacing as Pavement Preservation Technology TK Subhash Product Manager, Shell India Markets Pvt Ltd Abhishek Biswas Business Development Manager, Shell India Markets Pvt Ltd Janyajarasporn Yutthaporn Regional Technical Manager AP/IN/ME The Shell Company of Thailand Ltd Frits DeJonge Global Technology Excellence Manager, The Shell Company of Thailand Ltd ABSTRACT With hosting the Commonwealth Games 2010, the city of Delhi is gearing up its preparations for this mega event. Plans are underway for the provision of supporting facilities that cater for the requirements, which will arise during the influx of tourists and sports enthusiasts. The city is undergoing a major facelift in order to provide adequate infrastructure by 2010 and the Government of India is spending circa $17.5 billion for overall modernisation of the capital city. Transport is one of the significant areas under consideration by the planners. In particular, the roads providing the connectivity to the games stadium, hospitals and the games village are under focus. The total area to be paved is around 650,000 square meters. The city roads were overlaid three years ago with 50mm (2 inches) of asphalt concrete. After three years, the surface was rough and in some places heavy rutting defaults were observed. The pavement did not show any sign of structural weakness. The New Delhi Municipal Corporation (NDMC) was looking for the most cost effective alternatives to restore the surface conditions to the required level with regards to surface integrity and skid resistance. The NDMC was facing several important constraints: キ Heavy traffic during the day time making construction works during these hours impracticable キ A short duration for carrying out the works キ A ban of Hot Mix Asphalt Plants within the city limits キ Drainage constraints if the final pavement thickness increased significantly These constraints encouraged the NDMC to look at other solutions and micro surfacing was considered as an alternative Key words: micro surfacing, pavement, cost effective solution 1. Introduction The Delhi metropolitan area lies within the National Capital Territory of Delhi (NCT). The 2010 Commonwealth Games has provided a boost for the infrastructure in Delhi. The Government has planned to re-lay roads and install new electric lighting before the 2010 Games. By October 2010, all major roads in Delhi will have been revamped, freshly resurfaced and with new road markings. The public works department (PWD), the major road owning agency, has drawn up a map for micro surfacing of all stretches which were laid or resurfaced three years ago. The department has reportedly finalized the plan to use micro-surfacing technology to resurface over 400 kms length of PWD roads in the national capital. Maintenance is an essential activity for providing the required serviceability and durability of a pavement to the road user. It is established that appropriate and timely maintenance extends the 1 / 7

Upload: tk-subhash

Post on 05-Dec-2014

193 views

Category:

Technology


1 download

DESCRIPTION

Microsurfacing

TRANSCRIPT

Page 1: Microsurfacing paper issa world congress_english

7th ISSA WorldCongress, Lyon 2010

Micro surfacing as Pavement Preservation Technology

 

TK Subhash                                             Product Manager, Shell India Markets Pvt Ltd

Abhishek Biswas                                   Business Development Manager, Shell India Markets Pvt

Ltd

Janyajarasporn Yutthaporn                Regional Technical Manager AP/IN/ME The Shell Company of

Thailand Ltd

Frits DeJonge                                         Global Technology Excellence Manager, The Shell

Company of Thailand Ltd

ABSTRACT

With hosting the Commonwealth Games 2010, the city of Delhi is gearing up its preparations for this

mega event. Plans are underway for the provision of supporting facilities that cater for the

requirements, which will arise during the influx of tourists and sports enthusiasts. The city is

undergoing a major facelift in order to provide adequate infrastructure by 2010 and the Government

of India is spending circa $17.5 billion for overall modernisation of the capital city.

Transport is one of the significant areas under consideration by the planners. In particular, the roads

providing the connectivity to the games stadium, hospitals and the games village are under focus.

The total area to be paved is around 650,000 square meters.

The city roads were overlaid three years ago with 50mm (2 inches) of asphalt concrete. After three

years, the surface was rough and in some places heavy rutting defaults were observed. The

pavement did not show any sign of structural weakness. The New Delhi Municipal Corporation

(NDMC) was looking for the most cost effective alternatives to restore the surface conditions to the

required level with regards to surface integrity and skid resistance.

The NDMC was facing several important constraints:

· Heavy traffic during the day time making construction works during these hours impracticable

· A short duration for carrying out the works

· A ban of Hot Mix Asphalt Plants within the city limits

· Drainage constraints if the final pavement thickness increased significantly

These constraints encouraged the NDMC to look at other solutions and micro surfacing was

considered as an alternative

Key words: micro surfacing, pavement, cost effective solution

1. Introduction

The Delhi metropolitan area lies within the National Capital Territory of Delhi (NCT). The 2010

Commonwealth Games has provided a boost for the infrastructure in Delhi. The Government has

planned to re-lay roads and install new electric lighting before the 2010 Games. By October 2010, all

major roads in Delhi will have been revamped, freshly resurfaced and with new road markings. The

public works department (PWD), the major road owning agency, has drawn up a map for micro

surfacing of all stretches which were laid or resurfaced three years ago. The department has

reportedly finalized the plan to use micro-surfacing technology to resurface over 400 kms length of

PWD roads in the national capital.

Maintenance is an essential activity for providing the required serviceability and durability of a

pavement to the road user. It is established that appropriate and timely maintenance extends the

1 / 7

Page 2: Microsurfacing paper issa world congress_english

7th ISSA WorldCongress, Lyon 2010

service life of a pavement considerably. In construction and maintenance of roads by conventional

hot mix technologies, energy inputs begin from quarrying of stones and continue until the asphalt

mixture is finally installed. Cold mixed technologies involving use of bitumen emulsions provide

effective, energy efficient and long lasting solutions. The use of surfacing such as micro-surfacing

are ideally suited to the maintenance of urban roads, as applications are thin enough so that utility

accesses and curbs do not need adjusting. Maintenance of roads and roundabouts in New Delhi has

become increasingly difficult and the subject of much debate with the closure of hot mix plants by

Honorable Supreme Court of India.

Micro surfacing is considered as an alternative to thin hot mix renewals. The project attracted wide

media attention. The advantages of micro surfacing were widely reported in many major daily

newspapers. The articles described the performance of pavements treated with micro-surfacing

technique for a wide climatic temperature range.

This paper discusses the specification adopted, experiences gained and the performance of micro

surfacing on busy urban roads in New Delhi.

2. Pavement Condition

Table 1 below provide guidelines on serviceability indicators

Table 1: Guidelines for Maintenance of Pavements (Indian Road Congress, 1997)

 

 

Guidelines for Maintenance

Serviceability

Indicators

Urban (Heavy Traffic) Urban (Light Traffic)

Preventive Periodic Preventive Periodic

Benkelman

Beam

Deflection, mm

(maximum)

0.8 0.8 1.2 1.2

Distress, %

(maximum)

5 10 5 10

Roughness,

mm/km

(maximum)

2500 3500 2500 4000

Rutting, mm

(maximum)

8 16 8 16

Vehicle

Damage Factor

(maximum)

4 4 2 2

Thickness, mm 4-6 7-8 3-4 6-8

Quantity of

aggregate,

kg/m2

10-12 14-16 6-7 12-14

Type of grading III III II II

The pavements chosen for micro-surfacing treatments are often found to have severe rutting in

some locations and minor cracks can also be present, however the overall pavement condition is

2 / 7

Page 3: Microsurfacing paper issa world congress_english

7th ISSA WorldCongress, Lyon 2010

relatively good.

3. Constraints

The major constraints encountered on Delhi road maintenance are as follows:

- Heavy traffic during day time making work during day time impossible

- Duration of traffic block

- Ban of Hot Mix Asphalt Plants within city limits, therefore hot mix is required to be transported over

long distances

- The pavement thickness increase due to hot mix and subsequent issues of drainage / utilities

Considering the above constraints, micro-surfacing technology was adopted by NDMC

4. Application:

Key success elements identified for this project are:

- Opening to traffic in 1 hour and minimal interruption to traffic

- Chemistry and selection of emulsion components

- Emulsion properties for good and durable road performance

- Understanding aggregate quality, weather conditions and fine tuning the emulsion chemistry

- Application machinery and operators competence

- Construction procedures and management

The processes involved identification of aggregate sources, choosing the right gradation, designing

the emulsion as per aggregate and climatic conditions and skilful execution of the project. Each

stage of the process will be discussed briefly in turn

4.1 Identification of aggregate

The aggregates were identified after an extensive search in the region. The finalised source is from

Bahadurgarh, which is 120 km away from the project site.

The aggregate type is evaluated to be granite. The properties of aggregates as per Recommended

Performance Guidelines for Emulsified Asphalt Slurry Seal, 2005 - A 105 are evaluated in Table 2

(International Slurry Surfacing Association, 2005)

Table 2: Aggregate properties

Quality Test Method Specification Values

Sand

Equivalent

ASTM D 2419 -

2009

> 45 70

Abrasion

Resistance (%)

ASTM C 131 -

2006

< 35 12

 

4.2 Choosing the Aggregate Gradation

When tested in accordance to AASHTO T27 - 2006 (ASTM C136 - 2006) and AASHTO T11- 2005

(ASTMC117 - 2004), the target (mix design) aggregate gradation (including the mineral filter) shall

be within the band given in Table 3 below (International Slurry Surfacing Association, 2005)

Table 3: Aggregate Gradation as per ISSA Type III

3 / 7

Page 4: Microsurfacing paper issa world congress_english

7th ISSA WorldCongress, Lyon 2010

ASTM No #mm Type III

    Lower Upper

3/8 9.5 100 100

4 4.75 70 90

8 2.36 45 70

16 1.18 28 50

30 0.6 19 34

50 0.3 12 25

100 0.15 7 18

200 0.075 5 15

The gradation adopted is as per Type III (Recommended Performance Guidelines for Emulsified

Asphalt Slurry Seal, 2005 - A 105). The aggregate gradation was set at the quarry itself by adopting

suitable sieves (Fig 1: Aggregate Gradation achieved). It has been an excellent cooperation from the

quarry owner for making such adjustments in the process.

 

Fig 1: Aggregate Gradation achieved

 

 

 

4.3 Designing the emulsion

Designing the emulsion has been extremely challenging, due to the many variables in the process.

The emulsion specified is as per the Indian Standard, Table 4: Specifications of Emulsion for Micro

surfacing (IRC SP 81: Specifications for Slurry Seal and Micro surfacing, 2009). The emulsion

designed is using Synthetic latex.

Table 4: Specification for Emulsion for Micro surfacing

Requirement  Specifications Method of Test

4 / 7

Page 5: Microsurfacing paper issa world congress_english

7th ISSA WorldCongress, Lyon 2010

Residue on 600 Micron

Sieve (% Pass), Max

0.05 IS 8887

Viscosity by Say bolt

Furol Viscometer at 25C,

Sec

20 - 100 IS 8887

Coagulation of Emulsion

at low Temp

Nil IS 8887

Storage Stability after 24

h (168 h), % Max

2 (4) IS 8887

Particle charge +ve IS 8887

Tests on Residue:    

- Residue by

evaporation, % Min

60 IS 8887

 

- Penetration at 25C,

100g, 5 Sec

40 - 100 IS 1203

- Ductility at 27C, cm,

Min

50 IS 1208

- Softening Point, C, Min 57 IS 1205

- Elastic Recovery, % Min 50 IS 15462

- Solubility in

Trichloroethylene

97  IS 1216

The final mix design is given below in tables 5 and 6. Cement is used as the mineral filler in the mix.

Table 5: Mix Design Ratio

Aggregates, %  100

Cement, % 2

Added Water, %  10

Emulsion, % 13

 

Table 6: Properties of Designed Mix

ISSA Test No Description Specification Values

 

ISSA TB 139 Wet Cohesion 30

Minutes Min (Set)

12 kg cm Min 18 kg cm

  Wet Cohesion 60

Minutes Min

20 kg cm Min 33 kg cm

ISSA TB 114 Wet stripping Pass (90% Min) Pass

ISSA TB 100 Wet Track

Abrasion Loss,1

hr soak

807 g/m2 550 g/m2

ISSA TB 113 Mix Time 180 sec Min 180 Sec

 

5 / 7

Page 6: Microsurfacing paper issa world congress_english

7th ISSA WorldCongress, Lyon 2010

4.4 Execution:

There were many challenges faced during the execution of the micro surfacing. Frequently, even a

short blockage of traffic lead to large-scale discontent amongst commuters. The work had to be

compulsorily done in the night hours, which reduced the working window to between three and four

hours in a working shift. Therefore it was imperative that the emulsion set within one hour. The time

required for setting of emulsion also depends upon humidity as well as the ambient temperature. As

the temperature and humidity were in the extremes during the project, a continuous monitoring and

fine-tuning of emulsion chemistry was necessary. The huge success of the project has largely been

achieved by ensuring that the right emulsion has been used for the climatic and aggregate

variations. The average time taken to open the traffic on the freshly laid Micro-surfacing pavement

has been 1 hour.

4.4.1 Surface preparation

Any depressions in the surface were filled with a cold mix asphalt of appropriate grading suitable to

the depth of the depression and any visible cracks were repaired before applying the micro

surfacing. Severely cracked portions were removed and laid with cold mix prepared at site using

medium setting emulsions. The surface was cleaned by mechanical / power broom effectively before

application of the micro surfacing.

4.4.2 Calibration of Machine

In micro-surfacing works, the mix design is based upon the combined mass of dry aggregate and the

mass of mineral filler. To set the machine to a given mixture design and to produce a consistent

micro surfacing, accurate information on the delivery rates of the aggregate, emulsion, water and

mineral filler (cement) are necessary. A correction for natural moisture content in the aggregate is

also necessary for the mixture design. The Micro surfacing machine was thus frequently calibrated

for flow of aggregates, water, mineral filler (cement) and emulsion.

5. Regulation

National Highways Authority of India (NHAI) took note of this emerging technology in India and

studied the performance closely on various sections of pavement, which had been treated with micro

surfacing. Evaluation reports produced by the Central Road Research Institute (CRRI, 2005) helped

the NHAI to identify the benefits of this technology. Major conclusions of the various studies were:

- Need for reconstruction can be delayed using a thin layer of micro surfacing as preventive

treatment.

- Micro surfacing could be an alternative to thin hot mix renewals in maintenance of urban roads in

environment friendly manner and to saves energy.

- Only a marginal increase in pavement heights

- Faster laying process than HMA

- Effective quality control plays a vital role in success of a micro-surfacing projects

It is also indicated that Micro-surfacing treatment can fulfill the following different functions:

- Restores minor surface defects and acts as a protective layer. The inference drawn from the

experience and the data collected are as follows:

· One layer of micro-surfacing (7-8 kg/m2) brings down roughness values by about 200-300 mm/km,

which could be suitable mainly for preventive maintenance on structurally adequate pavement

· Two layers of micro-surfacing (15-16 kg/m2) help in reduction of roughness by 700-800 mm/km,

when used for periodic renewals in place of thin hot mix layer, provided roughness of original surface

is below 3000 mm/km. However, for periodic maintenance of surfaces with roughness over 3500

6 / 7

Page 7: Microsurfacing paper issa world congress_english

7th ISSA WorldCongress, Lyon 2010

mm/km, thickness of micro-surfacing needed will be around 12-14 mm, which can be achieved by

application of 28-30 kg/m2 of aggregate in multiple applications

In view of these established benefits, NHAI issued circular regularizing Micro surfacing treatments as

a preventive and periodic maintenance technique (NHAI, 2010).

6. Conclusions:

Road pavement maintenance and road pavement up grading are vital elements of road pavement

development and management programme. The fast growth in road pavement surface area offers

excellent growth potential for use of advanced technologies such as micro surfacing. Great efforts

have been made in co-ordination with local road authorities, and applicators to change the mind-set

of the markets and move to professional operations.

It is concluded that:

· Micro surfacing cannot rectify structural defaults, potholes and heavy rutting

· When the surface of existing pavement is uneven, the surface of single layer micro surfacing

application is also uneven. Experience shows that two-layer application has been successful over

cracked and patched surface.

· Environmental advantages

· No increase in road level due to thin layer application.

· Provide new friction and anti-skid resistance to the network

· Provide a protection sealing for the road surface and bridge-deck from water permeation. Restores

the surface condition and waterproofs the surface layer

· Emulsion chemistry allows a fast opening to traffic (minimal traffic interruption)

References:

Central Road Research Institute, Evaluation and Improvement Measures for Selected Roads of NDMC,

2005

Indian Road Congress, IRC 81 – 1997, Tentative Guidelines for Strengthening of Flexible Pavements

Using Benkelman Beam Deflection Techniques

Indian Road Congress, IRC SP 81 – 2009: Tentative Specifications for Slurry Seal and Micro surfacing

International Slurry Surfacing Association, Recommended Performance Guidelines for Emulsified

Asphalt Slurry Seal, A 105, 2005

National Highways Authority of India, Policy Matters – Technical, 2010

 

7 / 7