CONTRACTING: SLURRY SEAL GENERAL OVERVIEW PowerPoint Presentation Prepared For Seminar, May 3, 2001 Modesto, Ca. (Graphics Heavy - Thank you for your patience) Who Are VSS??? VSS has been in business over 50 years VSS are contractors VSS are manufacturers of emulsions VSS are suppliers of Raw materials VSS are manufacturers of Equipment VSS are Chemists VSS are Engineers VSS are Consultants History Family Company who started transporting asphalt in 1919 Hot Mix Companies for 70 years Quarry Companies for 70 years Slurry Pioneers since 50’s Emulsion plants since 80’s Equipment since 80’s Concrete since 80’s Asphalt Rubber and polymers since 90’s Countries Of Operation    Outline Pavement Preservation Concepts, Whole Of Life Costing, What It saves. Methods. Comparison of Methods on cost. Slurry Surfacing Definitions, overview, equipment. Slurry Seal Definitions, Materials( Emulsions, Polymers Aggregates, Additives), Design, Types and Uses, Performance, Preparation, Application, Cost Drivers. Microsurfacing Definitions, applications, differences to Slurry Seal, Types and Uses, Performance. Quality Control/Quality Assurance Basics, job requirements. Why do we have roads? To move people and goods safely quickly and efficiently To be an economic engine Roads must be passable Smooth All weather If you build it you must maintain it! Roads fall apart and you do not achieve design life if they are not maintained.    Lack of Maintenance costs MONEY Lost time Extra fuel Traffic jams Pollution Rebuilding costs Lost accessibility Social costs What do Bad Roads Cost? “Bad Roads Cost USA Motorists $41.5 Billion per year in extra fuel and repairs.” “28% are classified as POOR or MEDIOCRE.” “Road Information Project – Wall St Journal. April 3, 2001” Every Year Potholes Cause 4.8 Billion dollars worth of Damage to Vehicles* * SHRP HOW MUCH? What Can I save? Depends on situation USA 20% more effective if done in 5-7 year range (FHWA) 15% saving over life of pavement Arizona: 40-50% saving per lane mile for AR Singapore: 20% increase in life and 15% cheaper. (TRB 1998) Australia: 25% more effective, 20% saving over pavement life. (ARRB - Austroads) Preservation: Maintenance Stopping problems before they grow Maximizing the life of the pavement structure by PROTECTING it. Regular applications of preservation methods Quality Assurance systems PMS systems NOT WORST FIRST!!!!! Rehabilitation Repairing problems without reconstruction Follow up with preservation treatments Main Mechanisms Aging Water Damage Traffic Climate Main results Cracks Ruts Potholes Skid resistance loss Profile loss Water ponding Accidents Hold ups What Treatment? What will work? Preservation or rehab Distress analysis Cost Calculate cost effectiveness compared to other approaches This can be done by whole of life costing. A simpler way is to divide the total cost by the expected life increase. Calculate Net Present Value (NPV) Net Present Value Types of Preservation Methods Crack Sealing – waterproofing pavement Patching - water proofing improving ride Seal Coating - cosmetic surfacing Slurry Seal - sealing Microsurfacing - sealing Chip Seal - sealing Cape Seal - sealing surface profile HMA overlays - sealing surface profile Slurry Surfacing History Slurry Introduced late 40’s Polymer Modified Slurries 70’s Microsurfacing 80’s    Slurry Surfacing Usage Definition: A mixture of graded aggregate and bituminous binder with fillers and additives to make a cold mixed material that cures quickly to a hard wearing surface. Slurry Surfacing Cold Mix Placed in Situ Quick set/quick Traffic High Skid Low noise Durable Reasons For Slurry Surfacing A running surface for traffic A water resistant seal Minor shape correction Rut filling Improve skid Reduce noise Protect the base Where weight limits and curb height are important Slurry Seal What is it? Slurry is a mixture of graded aggregates, asphalt emulsion, additives and preferably polymers It is applied using a special paver mounted on a truck or self propelled Components are metered into a pugmill, mixed and spread on the surface at 1-1.5 top size stone thick Slurry is a hard wearing road surfacing What Does it do? Seals minor cracks Seals sound but oxidized pavements Restores surface texture and skid resistance Corrects raveling Reduces noise Allows overlays where weight restrictions apply Improves ride and profile aged pavement raveling pavement On PCC smooth low noise, water proof When Not to Use Slurry Surfacing by Itself Method A specific mix design is carried out for the aggregate. There are basically three types of aggregate, the selection depends on the job. The equipment is calibrated and the mix laid. The mixture is designed to a specific break and cure time - depending on conditions. The road may be opened to traffic after curing (30min-3 hrs depending on mix type and conditions. Mix Design Design Design Optimizing Asphalt Content Choosing Aggregate Choosing Polymer Choosing Additives Combining for the conditions to optimize durability Basic Design Questions Will it Mix? Will it Set? Will it Last? Will it be Safe? Will it Perform? Specification Issues Raw Material Properties Mixture Properties Method of Mixing Traffic Time Materials Emulsions Aggregates Additives Polymers Raw Materials: Emulsion Asphalt Dispersed in Water Sheared to a fine particle size Tests:Emulsion Binder Content Binder Properties ( base and recovered) Emulsion type Stability and other base emulsion properties Emulsion Types Slow set Quick set Quick set polymer modified Microsurfacing Specialised Emulsifiers Specialised Emulsions Emulsion Properties Test Typical Spec Method Residue 62% min AASHTO T59 Viscosity 25 C SSF 15-90 AASHTO T59 Sieve Content 0.3% max AASHTO T59 Settlement 1 day 1% max ASTM D244 5 days 5% max ASTM D244 Residue     pen 25C 40-90 ASTM D5 RBSP 57C min AASHTO T53 Aggregates Type : Geology Shape Texture Fractured faces Age Cleanliness Reactivity and Compatibility Grading Fines Content Physical Properties Aggregates Sieve Size III II I 12.5 mm 100 100 100 9.5 100 100 100 4.75 70-90 90-100 100 2.36 45-70 65-90 90-100 1.18 28-50 45-70 65-90 600 µm 19-34 30-50 40-60 300 12-25 18-30 25-42 150 7-18 10-21 15-30 75 5-15 5-15 10-20 Aggregate Gradings Aggregate Choice Smoothness Vs Skid Wear - traffic Pavement Use Color: Black aggregates are harder and keep their color I 99 Lodi Stockton special black mix 8 yrs old Where are they used? Residential streets; type II Arterial Roads: type II Freeways: type III Driveways; type II Parking lots: type I Airports: runways type I, taxiways type II Shoulders type II Low temperature Areas and high temperature areas type II or III Concrete Ramps and bridges, type II or type III Additives Improve strength Affect break and curing Alter grading Improve wetting and adhesion E.g.s cement, lime, surfactants What Polymers Do to Asphalt Elastomers are rubbery: they give high flexibility, good low temperature properties Plastomers are stiff: they give superior high temperature properties ALL polymers generally used will improve both high temperature and low temperature properties in compatible mixes with asphalt. What is a Polymer? Polymers are: Big: up to 100 times the largest asphalt molecule. Flexible: long chains. Form structures: crystals, cross links, entanglements. Polar: interact with other charged materials such as aggregates. What Types exist? Rubbery: Elastomeric: SBR, SBS, Natural Latex, Neoprene, Asphalt Rubber. Stiff: Plastics - Plastomers: EVA, EMA, PE Types Stretch: Rubbery elastomeric Resistance to Traffic High Stiffness: Plastomers Polymers Will Therefore: Increase softening point Increase binder viscosity Decrease Thermal susceptibility Increase elasticity Increase cohesion Increase low temperature tensile strength and flexibility Use Polymers to address problems Use Polymer to extend performance Design Steps Pre-screening Job Mix Final testing Job Mix Will it Mix? Aggregate is checked Emulsion is checked Hand Mixes and mix time is checked Job Mix Will it Set? A cohesion test is used on a range of emulsion levels.   Job Mix Will It Last? Optimization of binder content and film thickness Wet Track/ Loaded Wheel Use of Latex System Integrity Aggregate quality Adhesion Abrasion Testing Bitumen Optimization 1 hr AND 6 days soak!   LOADED WHEEL DEFORMATION BITUMEN OPTM DEFORMATION SAND PICK UP Compatibility System Integrity   Optimization Of Bitumen Content Job Mix Will it be Safe? Water based emulsion Safe additives Safe work practice Job Mix Will it Perform? Wet track abrasion Rolling wheel test Skid resistance Noise testing Stability testing for rutting Permeability testing Application Specifications Surface temperature and weather Application rate Rut filling requires tonnage application Surface Preparation Crack filling Traffic control Notification Clean Up Application Repair cracks and potholes Sweep Mask Services Apply Slurry Handwork Traffic Control Post Work if required Sweeping Cover Services Application 2-3 passes Handwork Application rates Type Appln Slurry (lb/yd2) Appln Slurry kg/m2 Appln Micro (lb/yd2) Appn Micro (kg/m2) I 6-10 3.27-5.44 not appl not appl II 10-15 5.44-8.16 10-20 5.44-10.88 III 20-30 10.88-16.32 20-30 10.88-16.32 IV not apl not appl 35-45 19.04-24.48 Performance:How Long Does It last? USA figures indicate 5-8 years for slurry. Internationally figures of 5-10 years are quoted. Jobs on highly trafficked roads are documented up to 15 years on sound pavements. Must be used on sound pavements or else another treatment is required like an asphalt rubber seal before the slurry is applied. What does it Cost? Cost Drivers: Slurry Microsurfacing What is it? Microsurfacing is a mixture of graded aggregates, a polymer modified emulsion and additives It is applied using a special paver mounted on a truck or self propelled Components are metered into a pugmill, mixed and spread on the surface at 2-3 top size stone thick It is high stability so may be spread in multilayers and provides a hard wearing surface or rut filler Microsurfacings break and cure to traffic ability in 30 min – 90 min minutes What Does it do? Restores surface profile Fills ruts Can be applied at night Suitable for low or very high traffic Suitable for all temperature ranges With Asphalt rubber and Carbon black will make blacker pavements     When to use Microsurfacing   Rut Filling depth of rut (in) depth of rut (mm) Application (lb/yd2) Application (kg/m2) 0.5-0.75 12.7-19.1 20-30 10.9-16.3 0.75-1.00 19.1-25.4 25-35 13.6-19.1 1-1.25 25.4-38.1 28-38 15.2-20.7 1.25-1.5 31.75-38.1 32-40 17.4-21.8 Design Similar to slurry Aggregates must be harder and higher SE (65) Set times faster More onerous requirements on compatibility and wear Stiffness requirement in LWT Application Method:     When is it used? All slurry applications - higher durability Freeways type III Major arterials type II Rut filling type III Airports type II Night work type II, III Extreme conditions type III         What Does it Cost: How Long Does it Last? Microsurfacing is laid thicker and has polymer. It is less expensive than standard rut-filling as milling is not required. As it is laid thinner than hot mix and on site it is less expensive. Microsurfacing lasts longer than slurry according to Californian and Texas figures. Ruts must be stable to get these results. Cost Drivers: Microsurfacing Quality Assurance and Control Who Decides? The customer is the final arbiter of quality. BUT! The process to achieve this quality must be agreed on before work begins. Customer service requires customer knowledge - QFD. To shed light on the subject requires data! Teams work better!! Quality Control Testing appropriate to job Minimize testing Testing by lots Correct sampling methods Correct sample handling Calibration Key Elements Sampling Materials testing Mix design Manufacturing control Field Control and procedure Inspection Corrective Action   Slurry/ Microsurfacing: Testing Emulsions Aggregates Mixes Calibration Application Methods         Quality Control On the Job Testing appropriate to the job Minimize Testing Testing by Lots Correct Sample Taking Correct Sample Handling Correct Sample Storage and Timely Testing Tighter does not always mean better. Emulsion Testing: Do within 48 hrs Binder Content Viscosity Settlement - stability Separation Lot Size: Batch Aggregate Testing Grading Lot size: Per delivery Moisture Test (after rain) Sand equivalent Standard Aggregate properties Lot size: At Mix Design Other Testing Machine Calibration for every aggregate within previous 12 months Mix Tests: At Design stage. Inspection (see ISSA Inspectors manual) Finish Joints Early raveling When there is a problem: Finding the solution requires cooperation! Keys To Slurry and Micro Surfacing Right materials Right Design Right Equipment Right Application and Quality Control Conclusions Slurry and Microsurfacing are powerful pavement preservation tools Quality systems must fit the situation VSS are always willing to help! For Contracting Products and Services contact pavements@slurry.com Copyright © 2000 Valley Slurry Seal Co All Rights Reserved.