Paving & Surfacing Module #6 Prepared by Dr. Randy R. Rapp July 2005

2005, Randy R. Rapp2 Bituminous Surface Treatment Duties Before Construction –Traffic control –Tools –Equipment Distributor volume gage calibrated Spray bar and nozzles –Discuss operations with contractor: consistency

2005, Randy R. Rapp3 Applying Asphalt & Stone Uniform asphalt application –Pump pressure and speed uniform? –Cover stone added to prevent bleeding Mineral aggregate –Correctly graded and damp –No skips, but do not place excess –Roll promptly –During curing period between prime and tack coats, broom accumulations so traffic coverage is uniform.

2005, Randy R. Rapp4 Classes B, C, & D Surface Treatments Broom clean Holes, breaks, subgrade failures repaired Apply asphalt according to conditions Pre-seal may be necessary Cure before sealing Fine screenings –Control bleeding –Reduce damage from rain on emulsions during curing

2005, Randy R. Rapp5 Inspection of Materials Asphalt –Weight certificate –Truck fully emptied –Delivery temperature –Samples drawn for laboratory testing Mineral aggregate approved by laboratory

2005, Randy R. Rapp6 Other Inspection Duties Protect structures from splashes Contractor keeps adequate equipment on- site during curing: responsive maintenance Measure stockpiles of aggregate –Depleted volume = placed volume? –Formulas: Conical Pile: V = (1/3) x Base Area x Height Triangular Pile: V = X-section Area x Length

2005, Randy R. Rapp7 Other Inspection Duties Stockpile formulas (cont’d) R = angle of repose (degrees) –Coarse aggregate: R = 35 o ; tan 35 o = –Fine aggregate: »If dry, R = 25 o ; tan 25 o = »If moist, R = 37 o ; tan 37 o = Conical Pile, D = diameter: –V = [D 3 x (tan R)] ÷ 7.64 –H = (½) x D x tan R Triangular Pile, B = base width: –V = (¼) x [B 2 x (tan R) x L] –H = (½) x [B x (tan R)]

2005, Randy R. Rapp8 Stress-Absorbing Membranes SAM (wearing surface) and SAMI (SAM interface): 2-lb rubber per gal asphalt Apply according to surface conditions: 0.5 gal/yd 2 ± 0.05 gal/yd 2 Spread aggregate 15 seconds after rubber mixture –SAM: 25 to 40 lb/yd 2 –SAMI 25 lb/yd 2 Roll at least 4 passes w/ 25-ton roller right after spreading

2005, Randy R. Rapp9 Asphalt Concrete Pavement Plant inspector duties –Meet all specifications –Ensure uniformity Aggregate gradation Feeding rate Heating and drying Separation into bins Mixing

2005, Randy R. Rapp10 Asphalt Concrete Pavement Plant inspector duties (cont’d) –Attitude Discuss planned operations with contractor’s superintendent and foremen Cooperation –Close communication with on-site inspector –Frequent inspections of departing batches: Consistency Distribution of asphalt and aggregate in mix Temperature Weight

2005, Randy R. Rapp11 Asphalt Concrete Pavement Plant inspector duties (cont’d) –Certified scale weights –Delivery tickets properly prepared –Truck beds lightly oiled –Temporary sites cleaned, stockpiled –Daily reports: separate if multiple plants –Checklist, p. 112 –Mix deficiencies, Fig. 6-3

2005, Randy R. Rapp12 AC Pavement On-Site Inspection Before paving –Traffic control –Inspection tools –Check contractor equipment Pavers –Tamper bar and fixed screed or –Transverse oscillating screed w/ vibrating plate –Track linkage adjusted –Tires all at correct pressure

2005, Randy R. Rapp13 AC Pavement On-Site Inspection Before paving (cont’d) –Check contractor equipment (cont’d) Pavers (cont’d) –Steel rollers true and no flat spots –Observe paver movement for minimal freeplay Compaction rollers –Vibratory types: speed <3-mph; vibes ≥33-cycle/sec –Pneumatic-tires same size and pressure (40 to 80-psi) Contractor tools

2005, Randy R. Rapp14 AC Pavement On-Site Inspection Before paving (cont’d) –Pre-leveling course Grader or paver Pneumatic roller –Untreated roadway

2005, Randy R. Rapp15 AC Pavement On-Site Inspection During paving –Tack coat Only what will be paved that day 0.02 to 0.08 gal/yd 3 –Transverse butt joints Heavy paper Joints between successive lifts ≥100-ft Taper for smooth transition Check with 10-ft straightedge

2005, Randy R. Rapp16 AC Pavement On-Site Inspection During paving (cont’d) –Spreading and finishing Machine cleaned Screeds at operating temperature Proper transverse butt joint if any delays No excessive paver speeds: multiple pavers, if production high –Longitudinal joints Minimal hand ranking Careful depth adjustment to adjacent lanes

2005, Randy R. Rapp17 AC Pavement On-Site Inspection During paving (cont’d) –Spreading and finishing (cont’d) Finished pavement imperfections, Fig. 6-6 Leveling course should eliminate wearing course screed adjustments –Compaction Breakdown, intermediate ≥185 o F; finish ≥150 o F Deeper lifts better: 400-tph with 3 rollers

2005, Randy R. Rapp18 AC Pavement On-Site Inspection During paving (cont’d) –Compaction (cont’d) Outer edges to center; lower to superelevated Constant movement within 200-ft of paver Overlap passes Max speeds: –Vibratory, 3-mph, usually for primary compaction –Pneumatic tired, 5-mph, usually for intermediate –Steel-wheeled, 4-mph, usually for finish

2005, Randy R. Rapp19 AC Pavement On-Site Inspection During paving (cont’d) –Compaction (cont’d) Steel-wheeled close behind pneumatic roller –Iron out tire marks –Compact centerline joint and edges Test sections –Types, passes, and patterns of equipment to meet specs –See pp Control: nuclear density meter and coring

2005, Randy R. Rapp20 AC Pavement On-Site Inspection During paving (cont’d) –Reports –Checklist, p. 129

2005, Randy R. Rapp21 Portland Cement Concrete Paving General instructions –Tools, instruments, and correct use –Necessary documentation and reports Before paving –Subgrade –Control stakes for wire –Fine grading

2005, Randy R. Rapp22 Portland Cement Concrete Paving Before paving (cont’d) –Inspect equipment Mixer Batch trucks Paver

2005, Randy R. Rapp23 Portland Cement Concrete Paving During operations –Paving spread Placing Consolidating Tie bars or dowels

2005, Randy R. Rapp24 Portland Cement Concrete Paving During operations (cont’d) –Finishing –Curing –Tests and Records –Joints Contraction Longitudinal Construction

2005, Randy R. Rapp25 Pavement Curing