Presentation on theme: "Chipseal Construction Section 37.2 Seal Coats. Proper surface preparation Use of right asphalt binder, asphaltic/polymer modified emulsion and clean."— Presentation transcript:
Proper surface preparation Use of right asphalt binder, asphaltic/polymer modified emulsion and clean aggregate screenings Adherence to the project specifications, including traffic control Check equipment before start Chip seal in good weather conditions
Materials Equipment Construction Procedures Quality Control Quality Assurance to be covered Topics to be covered Section 37-2.01A Summary
Construction Procedures Proper Surface Preparation Apply Binder/Asphaltic Emulsion/Polymer Modified Emulsion at Specified Rates & Temperatures Apply Screened Aggregates at Specified Rates Roll-as Specified Number of Coverages Allow Mat to Cure or Cool Broom Loose Aggregate Apply a Flush Coat Open to Traffic After Curing Flush Coat.
Sweeping (before and after) Hot Binder Application Aggregate Application Rolling
Construction- Surface Preparation-Existing Pavement Section 37-2.03D Surface Preparation Cover all exposed facilities before seal coat application. Reference all covered facilities properly for easy location. After seal coat application, expose the covered facilities.
Construction- Surface Preparation-Existing Pavement Section 37-2.03D Surface Preparation Remove all loose and extraneous material by brooming and vacuuming. Ensure clean, dry surface before applying seal coat.
Construction –Applying asphaltic Emulsion Section 37-2.03F
Section 37-2.03F Applying Emulsion In confined areas apply the emulsion with a squeegee, rake or other means authorized by the Engineer. Cover adjacent areas not intended for sealing with suitable material. At longitudinal joints, emulsion overlap must be dispersed with squeegees before the application of screenings or rakes. Construction –Applying asphaltic Emulsion
Section 37-2.03F Applying Emulsion Construction –Applying asphaltic Emulsion Align longitudinal seal coat joints with designated traffic lanes. Ensure adequate overlap (4”-8”), as directed by engineer. Plan emulsion application with lane closure requirements, stop an hour before darkness.
Chip Seal Type Application Rate Range (gallons per square yard) Fine0.15-0.30 Medium Fine0.25-0.35 Medium0.25-0.40 Coarse0.30-0.40 Asphaltic Emulsion or Polymer Modified Asphaltic Emulsion Application (Residual) Rates Section 37-2.03F(3) &(4) APHALTIC EMULSION APPLICATION RATES
Chip Seal Type Application Rate Range (gallons per square yard) Fine0.15-0.30 Medium Fine0.25-0.35 Medium0.25-0.40 Coarse0.30-0.40 Asphalt (Paint)Binder Application Rates APHALT BINDER APPLICATION RATES
Construction – SCREENED Aggregate Application Section 37-2.03G (1)(2) &(3)
Screened Aggregates SPREAD RATES Chip Seal Type Spread Rate Range (Pounds per square yard) Fine12-20 Medium Fine16-25 Medium20-30 Coarse23-30 Section 37-2.03G (1), (2) &(3)
No Traffic on emulsioned areas Uniform spread rates per specifications over entire lane width Broom Excess screenings. Aggregate screenings no roll after dropping. Aggregate screenings should stop when the spreader stops Do not spread aggregate screenings ≥ 2500’ ahead of completed initial rolling Construction – SCREENED Aggregate Application Section 37-2.03G (1) & (3)
The application always starts with neat straight edges. The aggregate spreader follows closely behind the distributor truck (50ft.) Screened aggregates for Polymer Modified Asphaltic Emulsion application are in a damp condition. The application looks uniform. Enough trucks are on hand to keep steady supply of chips. Check for streaks and gate plug. Screened aggregate sample is secured from the middle of stockpile or chip machine belt for testing. Construction – SCREENED Aggregate Application –BEST PRACTICES
Construction - Rolling Correct all ridges, piles, bumps or depressions. Ensure straight joints, no more than 4” overlap Longitudinal joints at lane lines Use pneumatic rollers Initial rolling with pneumatic roller one coverage Three coverages of pneumatic roller for final rolling Broom excess aggregate screenings before opening to traffic Section 37-2.03H(1)
Construction - Curing of Emulsion Curing time depends on ambient temperature and relative humidity Emulsion break should begin just after first roller pass Emulsion curing might take 2 to 6 hours, depending upon asphaltic emulsion type & base asphalt
Construction - Brooming Loose Aggregate Section 37-2.03I Seal Coat Maintenance
Seal coat surfaces must be maintained for 4 consecutive days from the day screened aggregates are applied. Remove excess screened aggregates from surface by brooming. Exact brooming time & intervals determined by engineer Use pilot cars to control traffic. Schedule placement to ensure end of 1 way traffic control an hour before darkness. Section 37-2.0I Seal Coat Maintenance
Quality Quality CONTROL-CONTRACTOR Screened Aggregates CT 211, Loss at 100 revolutions ≤ 10% Loss at 500 revolutions ≤ 40% CT 302, Film Stripping ≤ 25% C T 227 Cleanliness Value ≥ 80 for Asphaltic Emulsions C T 227 Cleanliness Value ≥ 86 for PMEs Section 37-2.0ID (3)
Quality Quality CONTROL-CONTRACTOR Screened Aggregates- CT 202 Gradation-Asphaltic Emulsion Section 37-2.02H (2) Percent Passing Sieve SizeCoarse ½” Max Medium 3/8” Max Med. Fine 5/16” Max Fine ¼” Max ¾” 100-- ½” 95–100100-- 3/8 ” 50–8090–100100 No. 4 0–155–3030–6060–85 No. 8 0–50–50–100–150–25 No. 16 --0–50–50–50–50–50–5 No. 30 -- 0–30–30–3 No. 200 0–20–20–2 0–20–2
Quality Quality CONTROL-CONTRACTOR Screened Aggregates- CT 202 Gradation-Polymer Modified Emulsion Section 37-2.02H (3) Percent Passing Sieve SizeCoarse ½” Max Medium 3/8” Max Med. Fine 5/16” Max Fine ¼” Max ¾” 100-- ½” 85–100100-- 3/8 ” 0–3085–100100 No. 4 0–50–150–5060–85 No. 8 --0–50–150–25 No. 16 -- 0–5 No. 30 -- 0–3 No. 200 0–2
Quality Control Inspection (cont.) Quality Control Pre- Application Inspection (cont.) Weather requirements Check the local weather conditions for the proposed paving day. Ensure that the proposed paving operation can be completed, including the emulsion cure within the favorable weather window. Reschedule paving operations if rain is predicted within the next 48 hours. Section 37-2.03C Unsuitable Day
Control Quality Control Inspection Pre-Application Inspection Surface preparation Equipment inspection Asphaltic emulsion distributor Chip spreader Haul trucks Rollers- Adequate number of pneumatic rollers Brooms Section 37-2.01(D) Quality Control
Quality Control Pre- Application Inspection (cont.) Determining asphaltic emulsion & screened aggregate application rates Traffic control plan and setup Section 37-2.03F(3) & (4) Application Rates
Quality ASSURANCE - construction Inspection Asphaltic emulsion application & rates California Test 339 Screened aggregate application & rates Vialit (French)Test ≥ 90% Retention Traffic control & trucking operation Rolling
Quality ASSURANCE - construction Inspection Longitudinal joints – ensure no aggregate buildup Transverse joints – ensure clean joints, start and stop on construction paper Brooming to ensure absence of loose aggregate
Quality Control /ASSURANCE Post-Application Inspection Cleanup Opening to traffic