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PennDOT Strategic Recycling Program Highlights. Background. Apex holds multiple contracts with PENNDOT Technical Assistance to Strategic Environmental Management (SEM) Program Office.
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PennDOT Strategic Recycling Program Highlights 0
Background • Apex holds multiple contracts with PENNDOT • Technical Assistance to Strategic Environmental Management (SEM) Program Office. • PENNDOT Strategic Recycling Plan: Research, specifications, project development, communications, contracting. • Use of recycled materials on maintenance and construction projects 1
Objective of SRP The objective of the SRP is “to realize economic savings and environmental enhancement to PENNDOT and the Commonwealth through the continued development of pollution prevention, recycling, energy efficiency, and sound environmental management practices”. 2
SRP Key Focus Areas Five key focus areas will be targeted to achieve and sustain PENNDOT’s mission to increase utilization of recycled materials in transportation engineering applications: • Research • Specifications • Project Development • Outreach • Contract Bidding 3
Apex as PENNDOT Recycling Coordinator PENNDOT SEM Program Office Contractors PADEP Outreach Material Suppliers A-EFirms Government Agencies Research Institutions PENNDOT Bureaus PENNDOT Engineering Districts 4
Recyclable Products/Materials • Scrap tires • Crushed Glass • Fly ash, bottom ash, MSWI ash, kiln dust • Slag and spent foundry sand • Compost (spent mushroom soil, • biosolids and leaf compost) • Asphalt shingles • Plastics, wood, aluminum • RPCC, RAP Ground asphalt shingles for use as an asphalt additive 5
Critical Factors The SRP allows PENNDOT to systematically implement and sustain its recycling program. Factors that are critical to the success of this program are: • Use of recycled materials should be cost competitive – not subsidized or mandated • Recycled materials should perform as well as conventional materials • There must be product consistency and quality control • Communications 7
Recent Demonstration Projects Glass cullet as aggregate in base course asphalt along shoulder of SR4013 in Manheim, Lancaster County. 9
Recent Demonstration Projects Installation of 2,000 tons of glass cullet between jersey barrier and sound wall along I-95 in Tinicum, Delaware County. 10
Recent Demonstration Projects Test trench containing flowable fill with recycled foundry sand as aggregate. Other usable aggregates include cullet, ash, and slag. Flowable fill is used to backfill utility trenches, sinkholes, and bridge approaches. 11
Recent Demonstration Projects Spent mushroom soil and composted biosolids used as soil amendment and mulch for new plantings at Beltway Beautification Project. (I-81/Rt. 322 interchange) 12
Recent Demonstration Projects Carsonite sound wall on I-78 bridge over Veracruz Road (Lehigh County). These sound walls are lightweight, modular, and contain recycled rubber. 13
Plasphalt Projects Asphalt containing ~1.5% TRPA substituted for stone aggregate. Incorporated in 9.5 mm Superpave wearing course TRPA: treated recycled plastic aggregate (shredded plastic) • Acts like chewing gum • Improves rutting resistance • Liquid Fuels Money applied Engineering District 5-0 Wilson Boro: 115 tons @ $78.89/ton Hay Terrace: 400 tons (lump sum bid) 14
Post Consumer Shingles Projects SR 4033, Bucks County, Engineering District 6-0 Control Section: 9.5 mm Superpave Virgin AC (1,300 tons) 1st Section: 9.5 mm Superpave w/ 5% shingles (1,000 tons) 2nd Section: 9.5 mm Superpave w/ 5% shingles, 10% RAP (1,000 tons) Bid as conventional paving Contractor initiated substitution 2-3 days paving Shingles 1.5% Asphalt content 100% passing 0.5-inch sieve 95% passing 3/8-inch sieve RAP 0.5 % Asphalt content 15
The Tire Problem - Pennsylvania • 12 million scrap tires are generated each year • 16 million currently stockpiled • Breeding ground for mosquitoes and rodents • West Nile virus concerns • Fires are hard to control and emit pollutants • Waste Tire Recycling Act (Act 190) is designed to reduce the waste tire problem 16
Tire Shred Use in Construction • Lightweight fill (40 to 60 pcf) • Mitigates slope stability or landslide problems • Mitigates excessive foundation settlement • Conventional fill (75 tires per cubic yard of fill) • Retaining wall and bridge abutment backfill • Insulation to limit frost penetration • French drains and drainage layers for roads 17
PENNDOT-PADEP Collaboration • First scrap tire recycling project in PA. • 750,000 tires (7,500 tons) used • Scrap tires from 7 community collection days, river sweeps, 6 abandoned tire piles, PADEP consent orders • Shredded tires used as lightweight geotechnical fill (50 1b/ft3) • Joint funding provided by PADEP 18
Shredding Site Bridge Site Tarrtown Project Locations 19
Project specifications • Tire Shreds • Length • Gradation • Deleterious materials • Free Steel • Exposed Steel • Embankment • Instrumentation 21
Tire Shred Specifications LENGTH: Not more than 1% and 10% (by weight) having a maximum dimension greater than 18-inches and 12-inches, respectively. GRADATION SIEVE SIZE PERCENT PASSING 8 inches75-100% 3 inches50% max. 1.5 inches25% max. No. 41% max. 22
DELETERIOUS MATERIALS: No oils, gasoline, diesel fuel, hydraulic fluid, grease, ice, and snow. No burnt tires. FREE STEEL: Less than 1% by weight of metal fragments. EXPOSED METAL: Provide at least 76% and 90% (by weight) of tire shreds with metal fragments encased in rubber that do not protrude more than 1- and 2-inches, respectively, from the cut edge of tire shreds. Tire Shred Specifications (cont’d) 23
Embankment Instrumentation • Vertical Inclinometers with settlement magnets • Automated Data Loggers & alarms • Web based reporting • Piezometers • Thermistors • Total Pressures cells • Settlement Plates 35
Piezometers & Thermistors Water Pressure (psi or kPa) Temperature (°C or °F) Cable lengths custom made 39
Total Pressure Cells Pressure (psi or kPa) • Embedded in concrete • Measures soil pressure • against abutments 41
Total Pressure Cells—Installed Embedded and calibrated in 1 ft by 1 ft concrete pads Flush-mounted on abutment formwork facing fill 42
Test Parameter Quarry-AR Quarry-CF Cullet-AR Cullet-CF Specific Gravity ASTM D854 Gs (-) 2.48 --- 2.49 --- Soil Classification ASTM D421, D422 USCS AASHTO SW No. 10 GP No. 8 SW No. 10 GP No. 8 Standard Compaction ASTM D698 γd,max (lb/ft3) γd,max [kN/m3] wopt (%) 111.9 17.6 11.9 93.5 14.7 6.5 107.5 16.9 13.2 99.2 15.6 12 Modified Compaction ASTM D1557 γd,max (lb/ft3) γd,max [kN/m3] wopt (%) 117 18.4 10.8 108.1 17.0 7.8 111.9 17.6 10.8 108.7 17.1 9.9 Direct Shear Test† ASTM D3080 φds (°) 61 54 56 48 CD* Triaxial Test† US Army COE φtx (°) 47 45 46 44 Key Crushed Glass Properties 43
Foundation Drainage Drainage Blankets French/Interceptor Drains Sand Filters (Wastewater) Well Packing Media Septage Field Media Leachate Collection Media Glass Cullet Applications • Base Course • Subbase • Embankments • Structural Fill • Nonstructural Fill • Utility Bedding and Backfill • Retaining Wall Backfill • Vapor Extraction Trenches 44
CG in SVE trenches • Challenge: SVE system needed near beach in coastal DE • Very sandy soils: need SVE trenches of greater permeability • Aggregates imported from inland quarries-- $$$ • CG from Ocean City, MD • 3/8” minus CG used • CG: $10/cy; Rock: $29.25/cy • 18 cy CG used • 30% savings where used. 45
Glass-Soil Blending Study • Concern: • “Modest” cohesion of the crushed glass (CG) suggested potential instability of shallow utility trenches and excavations. • Action: • Evaluated how soil blending could improve the cohesion characteristics of CG • Evaluated how CG blending improved the geotechnical characteristics of marginal soils (quarry fines, spoils). 46
Focus of the Laboratory Investigation • Crushed glass was blended with two clayey soils to evaluate improvement in cohesion • Kaolin Clay • Silty sand from King of Prussia, PA • A variety of marginal soils were blended with crushed glass to evaluate improvement in strength characteristics. • (K) Kaolinite • (KP) King of Prussia soil • (QF) Quarry fines (sandy silt) • (QS) Quarry screenings (coarse to fine sand) 47
Findings – Modified Proctor Compaction Tests • The maximum dry density of the soil-glass blends generally increased as soil content increased from 10% to 35%, but decreased thereafter. • The optimum water content of the soil-glass blends generally decreased as soil content increased from 10% to 35%, but increased thereafter. 49