Evaluation Report by CRRI

Report on “Laboratory Evaluation of Inssta Pattch

(a pressure sensitive compound for instant repairs of potholes)”

Flexible Pavement Division. CRRI, New Delhi

1. INTRODUCTION

Roads are the permanent assets built at huge capital investment for the safe and efficient

movement of goods and passenger traffic. However, the intended purpose of the roads would

not be fulfilled if it is not maintained properly. Poor road conditions not only invite public

criticism but also cause huge loss to the nation in terms of excessive usage of fuel and time.

Timely and adequate maintenance inputs extend the pavement life and reduce the road user

cost. The poor condition with pot holes are the source of public criticism and cost much more

to the road users also besides highway profession.

Flexible pavements with bituminous surfacing are mostly used for construction of roads in India

due to their cost effectiveness, ease in construction, maintenance and scope for stage

construction. Hot mixed bituminous materials are generally used for construction and

maintenance of wearing course of flexible pavements.

To the road user, pot holes are one of the most visible and annoying forms of bituminous

pavement deterioration. Potholes have always been a problem for highway maintenance

organizations because their treatment is very costly and time-consuming. The problem can

reach enormous proportions during cold, wet periods of the year, when pothole repair is made

more difficult because of adverse weather and the large number of potholes that seem to

appear at one time.

The formation of pot holes and ravelling of aggregate due to stripping is inevitable in rainy

season in bituminous surfacing. The patching of ravelled and cracked pavement surface during

service life is an important activity of routine maintenance. The patch work is also undertaken

for rectification if distress such as map and alligator cracking, depression, shoving, failed

patches, utility cuts and potholes. It is well known that the major cost of patching lies in

preparing and placing the patch rather than the cost of the patching materials. Therefore, it is

desirable that the process of patching should be simple and use good quality cold mix materials

to make patches last long.




The cold mixes are composed of liquid bituminous binders and aggregates that need not to be

heated. The mixtures are stockpiled until needed and used cold in any season.

The present report deals with laboratory evaluation of a ready-to-use patching material “Inssta

Pattch”, manufactured and marketed by M/s Akshay Innovations Private Limited, Nagpur.

2. IMPORTANCE OF READY–TO–USE PATCHING MIXES

Repair of heavily trafficked roads and highway pavements is very difficult using the

conventional materials and procedures. This not only causes inconvenience to the road users,

also are generally not very satisfactory. For such locations, ready-to-use patching materials are

essential for the regular maintenance of the pavements and cause minimal disturbance to the

traffic. Ready-to-use patching materials have various advantages, such as :

Quality of mix is consistent and uniform

Patches are more stable

Ready-to-use patching mixes need very little time for application at site

Pavement becomes traffic worthy soon after application. No curing period is required

Preparation of surface for repairs is minimal

Repair is possible even in all adverse climatic conditions

No wastage of materials and the manpower needed is minimum

A very common problem of urban areas is repair of utility cuts in the pavement. These

mixes provide quick and efficient repair with the least interference with traffic.

3. GENESIS OF THE PROJECT

3.1 General

CRRI was requested by M/s Akshay Innovations Private Limited, Nagpur to carry out the

laboratory investigation of their material – Inssta Pattch – a pressure sensitive compound used

for instant repair of potholes vide letter no. AIPL/CRRI/002/10-11 dated 03rd March, 2011. CRRI

agreed to take up the above consultancy project and charges for the same were communicated

vide letter no. QSP/CRRI/FPD/AIPL/Inssta/2010-11/18 dated 09th March, 2011.




The project started in the month of May, 2011 after the charges were received and DRRI

approval was obtained on 2nd May, 2011.

3.2 Objectives of the Study

The main objective of the study is to evaluate Inssta Pattch cold mix materials through

laboratory testing and semi-field studies to check its suitability for use as a repair material.

4. LABORATORY EVALUATION OF THE MATERIAL

4.1 Availability of Material

Inssta Pattch cold mix is available packed in disposable bags of 50 kg capacity, as supplied to the

Institute in ready to use condition. It is reported that the storage life of the material is about 12

months in sealed condition, if stored in a cool and dry place. After opening of bags, the material

is usable for 10-15 days. It was observed during the laboratory investigation work that material

in sealed condition can be used for 10 days after opening of the seal of the bags as the mix

remains in workable condition. The material does not emit any hazardous fumes during the

opening of the bags.

4.2 Evaluation of Material

The following studies were conducted in the laboratory for evaluation of the material.

Estimation of Volatile Matter

Estimation of Binder Content

Gradation of Washed Aggregates

Marshall Stability and Flow

Rolling Sieve Test

Tests for Moisture Susceptibility

Bond Strength by Shear Test (in the Laboratory)

Percent Retained Stability

All the results presented below are the average of 2-3 samples.




4.2.1 Estimation of Volatile Matter

About 1 kilogram of Inssta Pattch cold mix was spread in the thickness of 25 mm in a tray and

exposed to 160 °C temperature for 4 hours. The loss in weight was recorded as percent volatile

matter present in the mix to provide workability. The volatile matter present is estimated as

1.27 % of the mix. No hazardous fumes were seen and observed during the testing and heating.

4.2.2 Estimation of Binder Content

The binder content of Inssta Pattch cold mix was determined by cold extraction process using

trichloroethylene a solvent. The Inssta Pattch cold mix as supplied to CRRI contained 7.925 %

binder by weight of the mix.

4.2.3 Gradation of Washed Aggregates

The sieve analysis was conducted on the washed mineral aggregates as per the procedure

prescribed in IS:2386 (Part-1). The grading of washed aggregates is given in Table 1.

Table 1 : Sieve Analysis Results

Sieve Size, mm % Passing (as obtained in the Laboratory)

13.2 100.0

9.5 100.0

4.75 87.6

2.36 24.5

0.300 1.4

0.075 1.1

4.2.4 Marshall Stability and Flow

The Marshall stability of bituminous mix is the ability of the mix to resist deformation under the

action of load. For emulsion based cold mixes, the stability requirements are given for

maintenance only. For cutback based cold mixes, the stability requirements are given for both




maintenance and paving. However, since Inssta Pattch is to be used for maintenance purpose

only, so the requirements corresponding to maintenance for cutback based cold mixes are

taken for comparison with the results obtained in the laboratory.

For study of stability of Inssta Pattch cold mix, Marshall samples were prepared at ambient

temperature using 75 blows on each side. The samples were de-moulded after 24 hours from

the Marshall moulds. The samples were then tested for bulk density, stability and flow values

(at 25 °C) and the results are given in Table 2.

Table 2 : Results of Bulk Density, Stability and Flow of Inssta Pattch Cold Mix (at 25 °C)

Property Test Result Specified Limits as per MoRT&H, 2001

Bulk Specific Gravity 2.403 -

Bulk Density, gm/cc 2.396 -

Stability, kN 4.8 2.2 (for Maintenance)

Flow Value, mm 6.5 2 (Minimum)

Note : Density of water has been taken as 0.99704 gm/cc at 25 °C.

4.2.5 Rolling Sieve Test

The rolling sieve test was developed by the Ontario Ministry of Transportation to evaluate

stockpiled patching materials for durability under the abrasive action of traffic.

The test procedure adopted for this study consisted of the following steps :

(a) Fill the standard Marshall mould and collar with 1100 g of stockpiled Inssta Pattch cold mix.

(b) Using a standard Marshall hammer, compact the material in the mould with only three

blows of the hammer.

(c) Extrude and record the weight of the compacted sample.

(d) Place the compacted sample into a standard sieve with an opening of 25.4 mm (1 inch) and

a diameter sieve of 305 mm (12 inch) so that both the sieve and the sample are standing




upright. Place a lid on the sieve so that the sample is contained with the lid on one side and

the mesh on the other.

(e) Roll the sieve back and forth with the sample inside. The sieve should roll approximately

305 mm (12 inch) in each direction. The rolling continues for 20 passes, at approximately

one second per pass.

(f) After rolling, place the sieve horizontally with the mesh down. There should be enough

space to allow loose material to fall through the mesh. After 10 seconds in this position, the

sieve and lid should be turned over so that the material left in the sieve falls onto the lid.

(g) Weigh the material retained on the sieve. Calculate the percent of material lost as given

below :

Percent lost = 𝑊𝑜𝑟𝑖𝑔𝑖𝑛𝑎𝑙 − 𝑊𝑎𝑓𝑡𝑒𝑟

𝑊𝑜𝑟𝑖𝑔𝑖𝑛𝑎𝑙 × 100

The Ontario report stated that a loss of more than 35 percent was unacceptable.

The original laboratory procedure suggested by Ontario Ministry of Transportation

recommends the test temperature of -10 °C. However, such extreme cold temperatures are not

experienced in India. So, it was decided to conduct the test at three different temperatures viz.,

10 °C, 25 °C and 40 °C to represent the cold, medium and hot climatic conditions prevailing in

most of the parts of the country. The test apparatus is shown in Figure 1 and the test results of

rolling sieve test are presented in Table 3.

Table 3 : Rolling Sieve Test Results

Test Temperature Initial Weight, g Final Weight, g Percent Loss

10 °C 994.3 926.6 6.81

25 °C 998.5 949.3 4.93

40 °C 984.2 956.5 2.81

It can be seen from the above Table that the loss of the material for all the three temperatures,

viz., 10 °C, 25 °C and 40 °C is less than the recommended limit of 35 %.




Figure 1 : Rolling Sieve Test

4.2.6 Tests for Moisture Susceptibility

To evaluate the loss of adhesion due to effect of water, the following three tests have been

carried out.

4.2.6.1 Stripping Test on Loose Mix

This test was conducted as per IS:6241-1971 test method. About 200 gm of the mix was

transferred to a 500 ml beaker and filled with distilled water. The beaker is covered and kept in

the water bath maintained at 40° C, taking care that the level of water in the water-bath comes

up to at least half the height of the beaker. After the expiry of 24 hours the beaker is taken out,




cooled at room temperature and the extent of stripping is estimated visually while specimen is

still under water.

The stripping value was calculated as given below :

Stripping Value (in %) = Uncovered Area observed visually

Total area of the aggregates

No stripping was observed in the mix after 24 hours.

4.2.6.2 Boiling Test on Loose Mix

The boiling test (ASTM D 3625) is a quick and easy visual indication of chemical incompatibility

between the asphalt binder and aggregate. In this test, a sample of loose asphalt mixture is

placed in boiling water for 10 minutes and then removed. The extent of retained asphalt

coating on the aggregate is then evaluated relative to a non-conditioned sample. No stripping

was observed in the mix after the test. The condition of the loose mix after the boiling test is

shown in Photo 1.

Photo 1 : Condition of the loose mix after boiling test

4.2.6.3 Test for Retained Stability

This test measures the stripping resistance of a bituminous mixture. The Test is conducted as

per MS-14 (Appendix H) specifications. The standard Marshall specimens were prepared. The




specimens were kept in water bath maintained at 25°C for 4 days, i.e. 96 hours, and thereafter

tested for stability value. The results are reported as the percentage of Marshall Stability

determined in normal condition of the test. The results are presented in Table 4.

Table 4 : Results of Retained Stability Test

S. No.

Marshall Stability (at

25° C)

Marshall Stability (after soaking in

water for 4 days at 25° C)

Retained Stability (%)

Average Retained

Stability (%)

Specified Limits as per

MORT&H, 2001

1 505 392 77.6 77.3 75

2 485 367 75.7

3 481 378 78.6

It can be seen from the above Table that the Average Retained Stability obtained is more than

the specified limit of 75 % as per MoRT&H, 2001 specifications.

4.2.7 Bond Test

For the determination of bond strength between Inssta Pattch and existing surface, twin

Marshall specimens were casted using 50 % conventional bituminous concrete and remaining

with Inssta Pattch in cold condition with 75 blows on one side of the sample. The shear test was

conducted by applying load on Inssta Pattch portion of the specimen, at the joint, with a 25 mm

wide loading strip having curved surface inside. The average shear strength of 3 samples was

found to be 1.7 kg/cm2. This indicates good bond strength with existing surface using Inssta

Pattch cold mix. The test setup for the bond test is shown in Figure 2. Photos 2 to 4 show the

samples prepared for bond test, test setup and failed samples.




Figure 2 : A typical set up for determination of bond strength by shear test between two bituminous layers

Photo 2 : A view of the sample prepared for bond test

Old Surface

Inssta Pattch

Surface




Photo 3 : Test Set-up for Bond Test

Photo 4 : A view of failed samples after Bond test




5. FIELD STUDIES ON INSSTA PATTCH COLD MIX

The material was also evaluated in the field under heavy traffic. The field studies conducted

were very limited. The material was used at one location – Shastri Park Chowk to ‘O’ Pasta on

Marginal Bandh Road. The material was laid on a pothole on the left hand side of the road on

Shastri Park to Khajoori Lane. All loose material of pothole was cleaned off with the help of

brushes before the application of Inssta Pattch. Loose edges were removed by chisel and

hammer. Inssta Pattch was then filled up in the pothole with the help of shovels. The loose

material in the patch was levelled and compacted with the roller. The entire laying operation

was completed within 30 minutes with the help of only 2 labourers. The traffic was opened

immediately. The trial patch was subjected to heavy traffic. The patch was observed after a

period of one month and found to be stable and had good appearance. There was no stripping,

ravelling, bleeding or depression. It was decided that the final condition of the patch would be

evaluated again after one month. However, this could not be done since on this entire stretch,

extensive patch repair work has been done by the local authorities. The laying and rolling of

Inssta Pattch is shown in Photos 5 to 7.

Photo 5 : Inssta Pattch in ready to use condition




Photo 6 : A view of the pothole filled with Inssta Pattch material

Photo 7 : Rolling of Inssta Pattch material in progress




6. CONCLUSIONS

The Inssta Pattch cold mix is found suitable as ready-made mix for repair and maintenance of

bituminous roads specially for filling of potholes and utility cuts, as the various properties of the

mix such as stability, bond strength, moisture susceptibility and retained stability have been

found satisfactory and meeting the requirements as per the available specifications. The results

of limited field study indicate acceptable performance. The Inssta Pattch ready-mix is,

therefore, recommended for repair of potholes, ravelled surface and utility cuts in roads.




References

1. IS:2720 (Part 4) – 1985 (Reaffirmed 2006), “Methods of Test for Soils – Grain Size Analysis”,

Second Revision, Bureau of Indian Standards, New Delhi, 1986.

2. MoRT&H, 2001, “Specifications for Road and Bridges Works”, Fourth Revision, Ministry of

Road Transport and Highways, Indian Roads Congress, New Delhi, 2001.

3. ASTM D 1559, “Standard Test Method for Resistance to Plastic Flow of Bituminous

Mixtures using Marshall Apparatus”, American Society for Testing and Materials, Annual

Book of ASTM Standards, Volume 04.03, 2004.

4. ASTM D 4867, “Standard Test Method for Effect of Moisture on Asphalt Concrete paving

Mixtures”, American Society for Testing and Materials, Annual Book of ASTM Standards,

Volume 04.03, 2004.

5. ASTM D 2172, “Standard Test Methods for Quantitative Extraction of Bitumen from

Bituminous Paving Mixtures”, American Society for Testing and Materials, Annual Book of

ASTM Standards, Volume 04.03, 2004.

6. ASTM D 3625, “Standard Practice for Effect of Water on Bituminous Coated Aggregate

Using Boiling Water”, American Society for Testing and Materials, Annual Book of ASTM

Standards, Volume 04.03, 2004.

7. IS:6241-1971 (Reaffirmed 2003), “Method of Test for Determination of Stripping Value of

Road Aggregates”, Bureau of Indian Standards, New Delhi, 2003.

8. “Asphalt Cold Mix Manual”, Manual Series 14 (MS-14), 3rd Edition, Asphalt Institute, USA,

1989.

9. Wilson, Thomas P. And Romine, A. Russell, “Innovative Materials Development and Testing

Volume 2 : Pothole Repair”, Report No. SHRP-H-353, Strategic Highway Research Program,

National Research Council, Washington D.C., 1993.

Evaluation Report by CRRI

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