1. SESSION 9 Construction Considerations

2. Objectives  Describe key aspects of: Prepaving operations Paving operations Postpaving operations  Understand effects of pavement texturing  Identify benefits of initial pavement smoothness

3. Prepaving Activities  Subgrade preparation  Base preparation  Joint layout

4. Subgrade Preparation  Mixing in coarser material or stabilizer (as needed)  Fine grading and compaction  Accurate trimming to establish grade  Setting grade stakes

5. Base Placement

6. Joint Layout

7. Paving Activities  Mixing and transporting concrete  Placing concrete  Consolidating concrete

8. Mixing and Transporting Concrete  Optimize workability Mixing time and temperature Mix design (water, cement, gradation) Air content  Optimize finishability Fines content  Avoid segregation In every step of mixing, handling, transporting

9. Placing Concrete

11. Consolidating Concrete  Remove entrapped air  Distribute concrete uniformly around the dowels and reinforcement  Avoid under / overconsolidation Honeycombing Bleeding

12. Postpaving Activities  Finishing  Texturing  Curing  Joint sawing and sealing  Opening to traffic

13. Finishing  Screed off concrete surface level to desired height  Machine float to fill in low spots  Minimize hand finishing  Finishing too soon or too much will produce a surface with poor durability

14. Texturing  Initial texturing by burlap or astroturf drag behind paver  Tine texturing as soon has sheen of bleed water has disappeared  Separate machines used for tining and applying curing compound

15. Tine Texturing

16.  Important for surface friction and acceptable noise levels  Transverse tining most common procedure  For reduced noise levels, grooves: 3 to 5 mm deep 3 mm wide Variably spaced 10 to 40 mm apart

17. Curing  Enhance hydration and strength gain  Retain moisture and heat immediately after placement and finishing  Most common method: liquid membrane- forming curing compound Retains moisture, but not heat Blanket insulation may also be needed

18. Curing Compound

19. Joint Sawing and Sealing  Saw to establish contraction joints  Conventional sawcut dimensions: Depth: D/4 to D/3 typical Width: 3 mm (0.12 in)  Lightweight saws permit shallower cuts  Widening cuts for sealant reservoir

20. Sawcut Timing Time Concrete Set Sawcutting “Window” Too Late: Random Cracking Too Early: Excessive Raveling

21. Joint Sawing

22. Sawcut

23. Lightweight Sawing Equipment

24. Joint Preparation and Sealing

25. HIPERPAV Computer Program  Evaluates potential for uncontrolled cracking  Uses job-specific inputs for: Mix design Pavement design Construction Environmental factors

26. HIPERPAV Mix Design Inputs

27. HIPERPAV Pavement Design Inputs

28. HIPERPAV Construction Inputs

29. HIPERPAV Environmental Inputs

30. HIPERPAV Output

31. Initial Pavement Smoothness  Riding comfort  Improved long-term performance  Smoothness specifications: Improved initial smoothness levels Total roughness per unit length “Must-grind” bump Incentives/disincentives California profilograph

32. California Profilograph

33. Lightweight Profiler

34. Opening to Traffic  Time requirements  Strength requirements Beam or cylinder testing Maturity methods

35. Summary  Prepaving  Paving  Postpaving  Smoothness Subgrade preparation Base preparation Mixing and transporting Placing Consolidation Finishing Texturing Curing Joint sawing and sealing