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www.dot.state.pa.us USE OF POLYURETHANE GROUT FOR CONCRETE PAVEMENT SLAB STABILIZATION Indiana County District 10-0 Lessons Learned 1 Slide 2 www.dot.state.pa.us SR 422 Sec. 6 Indiana By Pass Slab Stabilization Project 2 Slide 3 www.dot.state.pa.us 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 Slide 4 www.dot.state.pa.us 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 Slide 5 www.dot.state.pa.us SR 422 Sec. 6 Mid-bay Crack Project Project traffic and Length DirectionADTLength Eastbound48413.07 miles Westbound49203.06 miles 7% Trucks Total 12 lane miles 5 Slide 6 www.dot.state.pa.us 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 Slide 7 www.dot.state.pa.us Project Overview 7 Slide 8 www.dot.state.pa.us The existing joints are in Good Condition 8 Slide 9 www.dot.state.pa.us Some Joint Distress but not extensive 9 Slide 10 www.dot.state.pa.us Mid-Bay Cracks 10 Slide 11 www.dot.state.pa.us Mid-Bay Cracks 11 Slide 12 www.dot.state.pa.us 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 Slide 13 www.dot.state.pa.us Slab Curling 10 in PCCP 4 OGS 4 2A Subgrade (Stiff to Hard Gravelly Silty Clay) 20 ft Joint Spacing Mid-bay Crack 13 Slide 14 www.dot.state.pa.us OGS Degradation 10 in PCCP 4 OGS 4 2A Subgrade (Stiff to Hard Gravelly Silty Clay) 20 ft Joint Spacing Mid-bay Crack 14 Slide 15 www.dot.state.pa.us 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 Slide 16 www.dot.state.pa.us Comparison of distress between Travel Lanes and Passing Lanes Travel LanesPassing Lanes EastboundWestboundTotalEastboundWestboundTotal DBR*5510015581018 Full Depth Patchs 4823127931417 Total103331434112435 Quantities as originally designed *DBR Dowel Bar Retrofits 16 Slide 17 www.dot.state.pa.us Grout Hole Spacing 20 ft 12 ft Traffic 3ft 6ft 17 Slide 18 www.dot.state.pa.us Drilling Grout Holes 18 Slide 19 www.dot.state.pa.us 19 Slide 20 www.dot.state.pa.us 20 Slide 21 www.dot.state.pa.us 21 Slide 22 www.dot.state.pa.us 22 Slide 23 www.dot.state.pa.us 23 Slide 24 www.dot.state.pa.us Mix Ratio Resin PartDensity Pounds/ US Gallon AIsocyanate FE 800 A-D10.16 BElastopor FE 663.018.95 Mix Ratio 50/50 by volume B/A=8.95/10.16 = 0.88 by density 24 Slide 25 www.dot.state.pa.us 25 Slide 26 www.dot.state.pa.us 26 Slide 27 www.dot.state.pa.us 27 Slide 28 www.dot.state.pa.us 28 Slide 29 www.dot.state.pa.us 29 Slide 30 www.dot.state.pa.us 30 Slide 31 www.dot.state.pa.us 31 Slide 32 www.dot.state.pa.us 32 Slide 33 www.dot.state.pa.us 33 Slide 34 www.dot.state.pa.us 34 Slide 35 www.dot.state.pa.us 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 to 1 inch. Unit Bid Price of Material is $4.30/pound 35 Slide 36 www.dot.state.pa.us 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 Slide 37 www.dot.state.pa.us 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 Slide 38 www.dot.state.pa.us Total Polyurethane Grout Cost Original Estimated Quantity 380,000 pounds $1.63M Actual Quantity 627,700 pounds $2.67M 38 Slide 39 www.dot.state.pa.us Iowa State Mobile Lab 39 Slide 40 www.dot.state.pa.us Iowa State Mobile Lab 40 Slide 41 www.dot.state.pa.us 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 Slide 42 www.dot.state.pa.us 42 Slide 43 www.dot.state.pa.us Example of Data presentation 43 Slide 44 www.dot.state.pa.us 44 Slide 45 www.dot.state.pa.us 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 Slide 46 www.dot.state.pa.us 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 Slide 47 www.dot.state.pa.us 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. 47 Slide 48 www.dot.state.pa.us 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 Slide 49 www.dot.state.pa.us 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 to 1 inch thick layer The grout did not block the drainage system 49 Slide 50 www.dot.state.pa.us 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 the amount of a patch and reduces the number of pavement joints. We are considering the elimination of the diamond grinding 50 Slide 51 www.dot.state.pa.us 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 Slide 52 www.dot.state.pa.us Use of Polyurethane Grout for Concrete Pavement Slab Stabilization Thank You Questions? 52