Concrete Paving Association of Minnesota CPAM Annual Workshop March 11, Gordy Bruhn- Senior Engineering Specialist

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1 Concrete Paving Association of Minnesota CPAM Annual Workshop March 11, 2016 Gordy Bruhn- Senior Engineering Specialist

2 FDR Removals I-94 Monticello, MN FDR Removals TH 2 Erskine, MN

3 Revised Reinforcing Steel Sizing from metric back to standard numbering of 1/8 th inch increments. For example: #13 mm bar is now a #4 bar. Type BE Repair

4 Allow either water or grout to bond the old and new concrete Continue to require grout to seal outside perimeter of the partial depth repair

5 Increased Drill and Grout Dowel Bar Size, From 1- inch to 1.25-inch Dowel Bar Diam. Full Depth Repair 12 wide (typical) Low Volume Full Depth Repair will Remain 1 Diameter Dowel Bars

6 1.25 Dowel requires a drill bit diameter of (1 3/8 min.)

7 Increased Minimum Number of Dowel Bars as Roadway Width Wider Required Start Dowels 1foot in from both ends Roadway Lane Width Dowel Bars Required Need to add an additional dowel bar per side for each 1 increase in lane width 12 feet 11 Dowels 13 feet 12 Dowels 14 feet 13 Dowels

8 Dowel Bars Supplied in Dowel Bar Assemblies will Remain 1-inch Diameter Dowel Bars

9 Projects with both Paving & CPR will separately tabulate dowel bars. Will include 2301 and 2302 Dowel Bar Pay Items

10 Transverse No.4 epoxy coated rebar length = Repair Width minus 2 feet

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12 Concrete Mixes previously designed by MnDOT now Contractor/Producer designed New mix numbers for all concrete mixes

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14 Concrete Grade R Pavement Rehab OLD Mix Number 3A32 3B42 NEW Mix Number 3R52 Intended Use CPR - Full depth concrete repairs, concrete base Maximum w/c ratio Maximum Cementitio us Content (lbs/cy) Maximum %SCM (Fly Ash/ Slag/ Ternary) Slump Range Minimu m Compres sive Strength, f c (28-day) 3137 Spec /35/ psi 2.D.3

15 Opened at a minimum of 48 hours of age and strength of 3000 psi HE concrete requires approval of the Engineer prior to incorporation into the work HE concrete requires control cylinders OLD Mix Number NEW Mix Number Table High-Early (HE) Concrete Requirements (Not applicable to Mass Concrete) Concrete Grades Allowed Minimum Time to Opening Maximu m w/c ratio Maximum Cementitio us Content (lbs/yd 3 ) * 3A22HE 3HE32 F 48 hrs A32HE 3Y43HE 3Y33HE 3Y46HE 3Y37HE 3A32HE Slump Range 1 3 Minimum Strength to Opening Minimum 28-day Compress ive Strength, f c 3137 Spec psi 4500 psi 2.D.1 3HE52 B, F, G 48 hrs psi 4500 psi 2.D.1 3YHE52 3RHE52 Y (Repairs Only) R (Repairs Only) 48 hrs psi 4000 psi 2.D.2 48 hrs psi 4000 psi 2.D.3 * Supplementary Cementitious Materials allowed. Adjust slump in accordance with G.7.a for slipform concrete placement.

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17 Standard Mixes UNCHANGED FROM PAST PRACTICES Store in same condition as structure Allowed to cure HE control cylinders in temperature monitored coolers Both the structure and storage/curing vessel need to be temperature monitored Must maintain temperature within storage / curing vessel at 5ºF of the poured concrete structure

18 The Contractor may choose to make additional control cylinders (beyond MnDOT s 3) to determine strength at any time other than 28-days. The Contractor may request the use of concrete maturity to determine opening to traffic, removal of forms, or loading.

19 MnDOT uses as part of acceptance Based on an average of 3 cylinders Cured under controlled conditions MnDOT Defined Curing Periods Moist Curing Environment Provided, By Contract

20 Initial Cure up to 48 hours Use of ventilation, Use of ice, Use of thermostatically controlled heating or cooling devices, or Use heating methods such as stoves or light bulbs. Other suitable methods are allowed provided the requirements limiting specimen storage temperature and moisture loss requirements are met.

21 The Contract requires providing moist curing environments of adequate size and number for initial and intermediate curing (first 7 days) of concrete cylinders Part of Field Office Spec ( C) If no Field Office, still required by Standard Specification (2461)

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23 2016 Spec Book Requirement Walks(2521) and Curb and Gutter (2531) Concrete Contractor or Subcontractor required to have the following: 2 - ACI Certified Flatwork Finisher or Technicians 1 required to be on site at all times

24 Questions?

25 Concrete Paving Association of Minnesota CPAM Annual Workshop March 11, 2016 Maria Masten, Concrete Engineer

26 Concrete Paving Updates Specification 2301

27 MnDOT has allowed two methods to achieve texture in concrete Astroturf Drag Broom Drag Beyond those requirements, we do not specify how to achieve the required texture.

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29 Broom Drag (Combined Texture and Cure Cart)

30 Broom Drag (Separate Texture Cart)

31 In 2015, lateral wandering with certain types of vehicles felt on some roadways Seems attributed to some broom texturing options Met with Industry to discuss options

32 Beginning November 2015 Astroturf drag only for mainline paving Broom drag allowed for lower speeds, edge of pavements and hand placed concrete Looking for volunteer project to install some different broom drag test sections in 2016

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34 Used for locating dowel baskets and centerline tie bars Original use ~ concrete pavement thickness Five (5) pilot projects using the MIT-SCAN T2 to determine the thickness of the concrete were conducted in 2015.

35 Evaluated the concrete thickness with the following: (1) Contractor Probing (1 per 1,000 lineal ft) (2) Probe Verification Scan (1 per 4 probes) (3) Quality Acceptance Core (1 per 4,000 lineal ft)

36 What we learned?? Probe vs. Scan Location Correlation was acceptable but not great Variation was likely caused by the probe measurements which are typically measured to the nearest 1/8 to 1/4 inch depending on the Contractor. Core vs. Scan Location Difference was typically a few hundredths of an inch.

37 What we are going to do different. Not require the Contractor to probe at specified locations they can probe at their discretion Instead, the Contractor will scan the concrete at the former probe locations (1 per 1,000 lineal ft) Required to core some of the scan locations for verification and a better comparison Reduce overall coring Scan Verification Core (1 per 8 scans) Quality Acceptance Core (1 per 8,000 lineal ft)

38 The MIT-SCAN T2 is currently being used to determine thickness by several state DOT s and is accepted by the FHWA. MnDOT s goal is for full implementation in 2017 or 2018.

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40 In 2015, MnDOT reviewed approximately 10 projects with unsealed joint test sections installed between Cored 5 projects In all cases where the seal was breached, the face of concrete cores looked worse than unsealed Well sealed joints looked the best

41 Seal the following: All Roadways: Speed limit 45 mph or less Whitetopping < 6 thick CPR projects: Speed limit 45 mph or less Bridge Approach Panels MnDOT Standard Plans updated to reflect unsealed joint recommendations

42 Questions?