use of polyurethane grout for concrete pavement slab stabilization
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USE OF POLYURETHANE GROUT FOR CONCRETE PAVEMENT SLAB STABILIZATION
Indiana County
District 10-0
Lessons Learned
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SR 422 Sec. 6 Indiana By Pass Slab Stabilization Project
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Existing Pavement Conditions
– Original construction 1995– 4 lane Limited Access Highway– Two 12 ft lanes each direction– Project length ~3miles– 12 lane miles treated– Shoulders 4 ft left, 10 ft right– 20 ft joint spacing
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Existing Pavement Conditions cont.
– Pavement section• 10 inch unreinforced PCCP
– Subbase• 4 inch OGS• 4 inch 2A
– Joints are in good condition – Main Problems –
• Mid Bay Slab Cracks• Slab settlement• Rocking• Some pavement distress
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SR 422 Sec. 6 Mid-bay Crack Project
• Project traffic and Length
Direction ADT LengthEastbound 4841 3.07 milesWestbound 4920 3.06 miles
7% Trucks Total 12 lane miles
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Slab Stabilization Scope of Work
– Slab Stabilization using Polyurethane Grout
– Slab Stabilization using Cement Grout(Comparison Section)
– Concrete Pavement Patching full depth– Dowel Bar Retro Fit Repairs– Crack Cleaning and Sealing– Joint Cleaning and Sealing
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Project Overview
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The existing joints are in Good Condition
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Some Joint Distress but not extensive
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Mid-Bay Cracks
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Mid-Bay Cracks
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Mid-bay slab cracking
10 in PCCP
4” OGS
4” 2A
Subgrade (Stiff to Hard Gravelly Silty Clay)
20 ft Joint Spacing
Mid-bay Crack
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Slab Curling
10 in PCCP
4” OGS
4” 2A
Subgrade (Stiff to Hard Gravelly Silty Clay)
20 ft Joint Spacing
Mid-bay Crack
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OGS Degradation
10 in PCCP
4” OGS
4” 2A
Subgrade (Stiff to Hard Gravelly Silty Clay)
20 ft Joint Spacing
Mid-bay Crack
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Dowel Bar Retrofit - Grout Stabilization
10 in PCCP
4” OGS
4” 2A
Subgrade (Stiff to Hard Gravelly Silty Clay)
20 ft Joint Spacing
Mid-bay Crack
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Comparison of distress between Travel Lanes and Passing Lanes
Travel Lanes Passing Lanes
Eastbound Westbound Total Eastbound Westbound Total
DBR* 55 100 155 8 10 18
Full Depth Patchs
48 231 279 3 14 17
Total 103 331 434 11 24 35
Quantities as originally designed
*DBR Dowel Bar Retrofits 16
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Grout Hole Spacing
20 ft 20 ft
12 ft
12 ft
Traffic
3ft
6ft6ft
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Drilling Grout Holes
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Mix Ratio
Resin Part Density Pounds/ US Gallon
A Isocyanate FE 800 A-D 10.16B Elastopor FE 663.01 8.95
Mix Ratio 50/50 by volumeB/A=8.95/10.16 = 0.88 by density
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Grout Application Rate Per Lineal Foot Of 12ft wide Pavement Slab
Pounds per Lineal Foot
Dollars per Lineal Foot
Lowest 9.5 lb/Lf $40.85Highest 15.0 lb/Lf* $64.50Average 13.0 lb/Lf $55.90
*Highest application rate occurred in areas where slab was raised ½ to 1 inch.
Unit Bid Price of Material is $4.30/pound
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Grout Application Rate Per Hole
Pounds Per Hole Dollars Per HoleLowest 16 lb/Hole $68.80/HoleHighest 35 lb/Hole $150.50/HoleAverage 23 lb/Hole $98.90/Hole
Unit Bid Price of Material is $4.30/pound
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Application Rate Per Day With 4 Trucks
Pounds Per Day Dollars Per DayGood Day 34,000 $146,000Bad Day* 11,000 $47,300Average 23,000 $98,900
* Equipment break down and or low air temperatures
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Total Polyurethane Grout Cost
• Original Estimated Quantity380,000 pounds $1.63M
• Actual Quantity627,700 pounds $2.67M
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Iowa State Mobile Lab
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Iowa State Mobile Lab
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Iowa State University- an overview of testing and some very preliminary results
• Tests were done before and after injection at both pavement joints and at mid bay cracks
• Falling Weight Deflectometer (FWD) testing measured both modulus and deflection giving joint efficiency
• Various subgrade density and modulus testing devices were used
• Load transfer efficiency• Pavement Elevation profile• Insitu densities• Subbase gradation• Subgrade Temperature probe
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SR-422 WB
Shoulder
Traffic Lane
Passing Lane
Shoulder
ABCD
Elevation Profiles
Easting (m)
650100 650110 650120 650130
Nor
thin
g (m
)
4497980
4497985
4497990
4497995
4498000
4498005
4498010
4498015
4498020
4498025FWD Before and After StabilizationFoam Injection LocationsCracksFWD After Stabilization
SR-422 WB
10 15 20 25 30 35 40 45
Def
lect
ion,
D0 (
mm
)
0.0
0.1
0.2
0.3
0.4
0.5 Sur
face
Mod
ulus
, EFW
D-K
3 (M
Pa)
0
1000
2000
3000
4000
5000
6000
10 15 20 25 30 35 40 45
Def
lect
ion,
D0 (
mm
)
0.0
0.1
0.2
0.3
0.4
0.5 Sur
face
Mod
ulus
, EFW
D-K
3 (M
Pa)
0
1000
2000
3000
4000
5000
6000
D0 Pre-StabilizationD0 Post-StabilizationEFWD Pre-StabilizationEFWD Post-Stabilization
Applied Load (Average) = 37.2 kN
Applied Load (Average) = 56.1 kN
10 15 20 25 30 35 40 45
Def
lect
ion,
D0 (
mm
)
0.0
0.1
0.2
0.3
0.4
0.5 Sur
face
Mod
ulus
, EFW
D-K
3 (M
Pa)
0
1000
2000
3000
4000
5000
6000
Applied Load (Average) = 75.3 kN
Distance (m)
10 15 20 25 30 35 40 45
Def
lect
ion,
D0 (
mm
)0.0
0.1
0.2
0.3
0.4
0.5 Sur
face
Mod
ulus
, EFW
D-K
3 (M
Pa)
0
1000
2000
3000
4000
5000
6000
Applied Load (Average) = 106.5 kN
JointCrack
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Example of Data presentation
10 15 20 25 30 35 40 450
20
40
60
80
100
Pre-StabilizationPost-Stabilization
10 15 20 25 30 35 40 45
Load
Tra
nsfe
r Effe
cien
cy, L
TE (%
)
0
20
40
60
80
100
Pre-StabilizationPost-Stabilization
Applied Load (Average) = 56.3 kN
Joint
Crack
Applied Load (Average) = 37.4 kN
Joint
Crack
Distance (m)
10 15 20 25 30 35 40 450
20
40
60
80
100
Pre-StabilizationPost-Stabilization
Applied Load (Average) = 106.2 kN
Joint
Crack
10 15 20 25 30 35 40 450
20
40
60
80
100
Pre-StabilizationPost-Stabilization
Applied Load (Average) = 75.6 kN
Joint
Crack
PennDOT SpecificationTarget LTE = 65%
PennDOT SpecificationTarget LTE = 65%
PennDOT SpecificationTarget LTE = 65%
PennDOT SpecificationTarget LTE = 65%
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10 15 20 25 30 35 40 450
20
40
60
80
100
Pre-StabilizationPost-Stabilization
10 15 20 25 30 35 40 45
Load
Tra
nsfe
r Effe
cien
cy, L
TE (%
)
0
20
40
60
80
100
Pre-StabilizationPost-Stabilization
Applied Load (Average) = 56.3 kN
Joint
Crack
Applied Load (Average) = 37.4 kN
Joint
Crack
Distance (m)
10 15 20 25 30 35 40 450
20
40
60
80
100
Pre-StabilizationPost-Stabilization
Applied Load (Average) = 106.2 kN
Joint
Crack
10 15 20 25 30 35 40 450
20
40
60
80
100
Pre-StabilizationPost-Stabilization
Applied Load (Average) = 75.6 kN
Joint
Crack
PennDOT SpecificationTarget LTE = 65%
PennDOT SpecificationTarget LTE = 65%
PennDOT SpecificationTarget LTE = 65%
PennDOT SpecificationTarget LTE = 65%
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Some key findings are as follows:
• Load transfer efficiency for the joints is about 79% before and after stabilization
• Load transfer efficiency for the mid-panel cracks is about 43% before stabilization and 88% after stabilization
• Corner slab deflections post-stabilization are less than 0.5 mm
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Slab elevation changes
• There was an elevation change of about 0.25in. on average in test section 6
• There was an elevation change of about 0.8in on average in test section 7. This section also took twice as much material
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Comparison with Portland Cement Grout
• The polyurethane performance will be compared to a 1,300 foot (~67 slabs) test section which will be grouted using portland cement grout during the construction season of 2010.
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Summary and observations
• The OGS showed signs of particle degradation allowing for some slab rocking
• The 2A appeared to be stable
• The subgrade was stiff to hard
• The mid-bay cracks appear to be due to slab curling.
• The polyurethane grout is effective in stabilizing slab movements
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Summary and Observations Cont.
• The Grout was effective at penetrating the clean OGS layer but it did not penetrate the 2A layer
• The grout is effective at lifting the slabs but it appeared difficult to accurately control the movement
• The grout coated the bottom of the slab with ¼ to 1 inch thick layer
• The grout did not block the drainage system
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Based on the observations and information collected the following contract changes have been made
• We increased the polyurethane quantity to include total grouting of the passing lane
• We reduced the quantity of full depth patches and increased the quantity of DBRs. – The DBRs cost about ½ the amount of a patch and
reduces the number of pavement joints.
• We are considering the elimination of the diamond grinding
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Based on the observations and information collected the following contract changes have been made
• The District has modified the special provision base on information from this project. Major changes include adding more quality control procedures
• Iowa State will monitor the grout performance over next three years
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Use of Polyurethane Grout for Concrete Pavement Slab Stabilization
• Thank You
• Questions?
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