USE OF POLYURETHANE GROUT FOR CONCRETE PAVEMENT SLAB STABILIZATION Indiana County District 10-0 Lessons Learned 1

SR 422 Sec. 6 Indiana By Pass Slab Stabilization Project 2

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 3

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 4

SR 422 Sec. 6 Mid-bay Crack Project Project traffic and Length DirectionADTLength Eastbound miles Westbound miles 7% Trucks Total 12 lane miles 5

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 6

Project Overview 7

The existing joints are in Good Condition 8

Some Joint Distress but not extensive 9

Mid-Bay Cracks 10

Mid-Bay Cracks 11

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 12

Slab Curling 10 in PCCP 4” OGS 4” 2A Subgrade (Stiff to Hard Gravelly Silty Clay) 20 ft Joint Spacing Mid-bay Crack 13

OGS Degradation 10 in PCCP 4” OGS 4” 2A Subgrade (Stiff to Hard Gravelly Silty Clay) 20 ft Joint Spacing Mid-bay Crack 14

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 15

Comparison of distress between Travel Lanes and Passing Lanes Travel LanesPassing Lanes EastboundWestboundTotalEastboundWestboundTotal DBR* Full Depth Patchs Total Quantities as originally designed *DBR Dowel Bar Retrofits 16

Grout Hole Spacing 20 ft 12 ft Traffic 3ft 6ft 17

Drilling Grout Holes 18

19

20

21

22

23

Mix Ratio Resin PartDensity Pounds/ US Gallon AIsocyanate FE 800 A-D10.16 BElastopor FE Mix Ratio 50/50 by volume B/A=8.95/10.16 = 0.88 by density 24

25

26

27

28

29

30

31

32

33

34

Grout Application Rate Per Lineal Foot Of 12ft wide Pavement Slab Pounds per Lineal Foot Dollars per Lineal Foot Lowest9.5 lb/Lf$40.85 Highest15.0 lb/Lf * $64.50 Average13.0 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 35

Grout Application Rate Per Hole Pounds Per HoleDollars Per Hole Lowest16 lb/Hole$68.80/Hole Highest35 lb/Hole$150.50/Hole Average23 lb/Hole$98.90/Hole Unit Bid Price of Material is $4.30/pound 36

Application Rate Per Day With 4 Trucks Pounds Per DayDollars Per Day Good Day34,000$146,000 Bad Day*11,000$47,300 Average23,000$98,900 * Equipment break down and or low air temperatures 37

Total Polyurethane Grout Cost Original Estimated Quantity 380,000 pounds $1.63M Actual Quantity 627,700 pounds $2.67M 38

Iowa State Mobile Lab 39

Iowa State Mobile Lab 40

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 41

42

Example of Data presentation 43

44

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 45

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 46

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

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 48

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 49

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 50

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 51

Use of Polyurethane Grout for Concrete Pavement Slab Stabilization Thank You Questions? 52