Asphalt Guidelines. Courtney Rousseau, P.E. Lloyd Consulting Group, LLC

Transcription

1 Asphalt Guidelines Courtney Rousseau, P.E. Lloyd Consulting Group, LLC

2 Objectives Review typical asphalt sections and other key components to ensure optimal material usage for your project Review hot mix asphalt (HMA) surface preparation and how to troubleshoot common issues prior to asphalt placement Understand the critical testing and quality control operations Explore various cost savings options for tight project budgets Image Source:

3 Materials Aggregate Base Angular crushed stone or gravel and well graded sand Proper subgrade preparation is critical Amend and compact to geotech. recommendations Slurry backfill on utility trenches Image Source: Tacking/Priming Tacking = between lifts Priming = atop aggregate base Image Source:

4 Materials (cont.) Base Course Max. aggregate size (MAS) ¾ 1 Leveling Course Variable thickness placement MAS no greater than the surface course Surface Course Set to all finished lines and grades Fine graded MAS ½ maximum Nominal 3/8 or smaller Minimum average 1 ½ thickness Absolute minimum 1 ¼ thickness **Exceptions allowable for some low volume, fine graded asphalt mixtures

5 HMA Mix Design Numerous mix design criteria (often looked over or trusted that manufacturer followed specifications correctly) Aggregate gradations Specific Gravity Asphalt Content Air voids Dust content Design specifications approved before and throughout production Source: ASBA Asphalt Guidelines

6 Ensuring the Best Product Qualified suppliers Approved and certified Strong track record Reliable point of contact Timely submittals Prior to and throughout construction Proper testing procedures Qualified technicians Follow and record quality control protocol Image Source:

7 Surface Preparation 1. Repair pavement failures and existing cracks 2. Grind or mill abutment edges to allow smooth transition 3. Evaluate the potential need for wedging 4. Clean the surface to be free of dirt, debris, dust, etc. 5. Scrape and treat oil or grease spots to prevent bleeding prior to applying tack coat 1) Sweep any excessive tack coat applications 2) Apply at rate as prescribed in the project specifications 6. Remove any moisture Source: MAG Standard Details **ALWAYS PERFORM WORK UNDER SUITABLE WEATHER CONDITIONS

8 Edge Transitions Synthetic Turf & Natural Grass Pavement Synthetic Turf Transition Landscaping Pavement Transition Landscaping Transition

9 Testing & Quality Control HMA material tests taken in the laboratory prior to mass manufacturing and throughout production Must complete submittal checklists required Temperature tests ensure HMA is between F Relative humidity Air void content <7 8% In place density testing taken every 400 tons or once daily Surface courses = % of Gmm Base/leveling courses = min. 92.0% of Gmm Base/leveling course joints = % individually, daily average of 98% Image Source: Google

10 Testing & Quality Control (cont.) Submit and follow an Asphalt Placement Work Plan to coordinate smooth execution of the work Record pertinent information throughout the project Temperatures, in place densities, rolling patterns, etc. Tolerances Base/leveling courses = 1/4 in 10 ft Surface course = 1/8 in 10 ft Ponding tolerances 1/8 in 10 ft

11 Cost Saving Opportunities In Place Asphalt Recycling Over 100M tons of recycled asphalt pavement (RAP) is used every year Many plants stockpile RAP for reuse Maximum 20% allowed in binder/base and leveling courses Maximum 15% allowed in surface course QC testing of RAP submitted to owner prior to mix design acceptance Estimated asphalt production cost categories. (source: FHWA)

12 Cost Saving Opportunities In Place Asphalt Recycling Benefits Reduce virgin aggregate and virgin asphalt binder needed Conserves energy/preserves resources Lower transportation costs/reduce haul off Challenges Potential existing contamination (must meet design specifications) Availability Tying into existing boundaries

13 Cost Saving Opportunities Manipulating Section Depths 1 Asphalt = 3 Asphalt Base Reduce high export costs from excavating for AB Image Source: Google

14 Questions? THANKS ASBA!