2015 ctaa course november 15, 2015 final as presented · 2015-11-15 · 11/15/2015 2 pavement...

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Tom Dziedziejko, C.E.T Reza Namjouy, P.Eng.Director of Quality, Infrastructure Senior Pavements EngineerAecon Aecon Materials Engineering

Tom Dziedziejko, C.E.T Reza Namjouy, P.Eng.Director of Quality, Infrastructure Senior Pavements EngineerAecon Aecon Materials Engineering

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2015 CTAA CourseCold-In-Place Recycling

2015 CTAA CourseCold-In-Place Recycling

Course Outline

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o Pavement Structure Overview

o Drainage

o Candidates For Recycling

o Foamed Asphalt – BSM-Foam

o Full Depth Pavement Recycling

o Emulsified Asphalt – BSM-Emulsion

o Partial Depth Pavement Recycling

Course Outline

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o Preliminary Construction Analysis

o Mix Design

o MTO Test Method LS-297, LS-300

o Additives to Enhance Mix Properties

o In-Place Recycling Construction

o Field Testing

o Laboratory Testing

o Project Experience

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Pavement Structure Overview

Pavement ComponentsRigid and Flexible PavementsUnbound, Non-Continuously Bound and Bound Materials

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Pavement Structure Overview Componentso Pavements are comprised of three basic components:

o Surface – The riding surface which is usually the only part of the road visibleo Structural Layers – The load spreading layers, consisting of different

materials, depth dictated by traffic loading and underlying support.o Subgrade – The existing ground which supports the pavement

o Primary Function of Pavement Steuctures:o Reduces the applied stress to a level that existing ground may support

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Load Transfer

Pavement Structure OverviewRigid and Flexibleo Two fundamental types of pavement:

o Rigid Pavements – Constructed with a thick layer of high strength concrete overlaying a unbound layer

o Flexible Pavements – Constructed from natural materials with the upper layers bound (normally by bitumen) to achieve the higher strength

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Consider the Stresses and Materials

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Pavement Structure OverviewUnbound, Non-Continuously Bound & Boundo Pavement structure generally consists of

several layers of material with different strength and stiffness characteristics

o Each layer serving the purpose of distributing the load it receives at the top over a wider area at the bottom

o Bound Materialso Cemented materials that act more like a wide

beam; distributing applied loads o Compression stress at the top and tensile stress

at the bottom of the layers

o Unbound Materialso Granular materials:

o crushed stone and gravels transfer applied loads through individual particles

o Inter-particle friction maintains structural integrity

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Unbound - Granular

Bound – Hot Mix Asphalt

Pavement Structure OverviewUnbound, Non-Continuously Bound & Bound

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o Non-Continuously Boundo Foamed or Emulsified bitumen stabilized materials, behave

like granular materials with retained inter-particle friction but increased cohesion and stiffness

Non-Continuously Bound –Foamed Asphalt

Drainage

Importance of Drainage

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Importance of DrainageGeneral Overview

o Water is the greatest enemy of road structures

o Water saturation causes:o Materials to soften and weather, and

also provides inter-particle lubrication when load is applied

o Hydraulic pressures when subject to loading – PUMPING!!

o Bearing capacities of materials in the dry states are significantly greater than those in the wet and cohesive states

o Reduces the strength of unbound granular material and subgrade (especially for fines)

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Pumping

Importance of Drainage Drainage Design

o Well-drained base courses and subgrade are better for roadway/pavements

o Moisture is a major cause of distress

o Many sources of moisture in pavements

o Drainage Systems Are Required

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Poor Drainage

Importance of DrainageSurface Drainage

o Pavement and shoulderso Full width, impervious surface with sealed shoulderso The pavement should be maintained without cracks or holes

o Curbs and gutterso Storm Sewerso Crowns / Cross Slopes

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Surface Drainage

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Importance of Drainage Sub-Surface Drainage

o Interception drainageo Take the water away!!!

o Subgrade drainageo Allow for drainage of water at

subgrade level

o Base drainageo Prevent saturation of base

materials

o Special Mixeso Open-graded / Permeable Mixeso drain water to the sides or

through the structure.o Appropriate drainage systems

required

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Sub-Surface Drainage

Candidates for Recycling

What Types of Pavements are Recycled with Cold Recycled Technology?

BSM-Emulsion or BSM-Foam? Why use a Cold Recycling Technology?

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Candidates for Recycling

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Pavement with Surface Distresses

o Suitable candidates for all recycling processes have surface distresses and structural deficiencies such as: o Cracked Pavementso Potholed Pavementso Rutted Pavementso Flushed Pavementso Severe Oxidationo Exceeded Design Life

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Candidates for RecyclingProject Pictures

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Candidate Selection


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Candidate Selection


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Candidate Selection

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Candidate Selection


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Candidate Selection – Base

Failure

Preliminary Construction Analysis

Data AcquisitionPreliminary and Detailed InvestigationsSuitability of Materials, Pavement Design

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Preliminary Construction AnalysisData Acquisitiono The following information should be gathered:

o Traffic data to determine the structural capacity requirementso Functional properties of the rehabilitated roado Historical and existing pavement compositiono Intended design lifeo Available budget

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Traffic Counter Gather Information

Preliminary Construction AnalysisPreliminary Investigationo Preliminary investigations are

undertaken to determine and analyze similar sections along the pavemento Existing pavement structureo Deflection datao Visual inspection records

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Typ. Deflection Bowl

Fall Weight Deflectometer (FWD)

Boreholes / Geotechnical Investigation

Asphalt Core Depths

Preliminary Construction AnalysisPreliminary Investigationo Test pits are an important source of information concerning

existing pavement structureso Individual pavement layerso Moisture content of the in-situ material in each layero In-situ density of the material in each layero Condition of the material in the various layers

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Test Pits

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Preliminary Construction AnalysisDetailed Investigationo Ground Penetrating Radar

o Verify pavement sections are uniform between asphalt cores, boreholes and test pits

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Cart Configuration Vehicle Mounted Configuration

Preliminary Construction AnalysisDetailed Investigation

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Determine Distress Manifestations

Preliminary Construction AnalysisSuitability of Materials

o Testing of the materials sampled from the detailed investigation is used to determine the suitability of the material for incorporation into a mix designo Sieve analysiso Atterberg Limits – Plasticityo Existing Asphalt Properties

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Plotting FWD, Thickness and Lab Test Results across Rehab. Section

Determine Asphalt Properties

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Preliminary Construction AnalysisPreliminary Pavement Design

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ASSHTO-Ontario Structural Layer Coefficient (SLC) for use to

Determine a Structural Number (SN) that Characterizes the Structural

Capacity of the Layer

Preliminary Construction AnalysisPreliminary Pavement Design

o Run interim pavement designso Determine a logical rehabilitation alternative!

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Preliminary Pavement Design Alternatives

Next consider the binder to use for stabilization…

BSM-Emulsion and BSM-Foam Material Comparison

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Typical Binding Agents for Recycling In-Situ

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BSM-Emulsion and BSM-Foam Why Use it?

o Use of existing in-place road material to produce a high performing pavement base structure

o Minimal cost of materialo Cost effectiveo Reduced emissions compared to traditional rehabilitation methodso Quick turnaround for clients and reduced traffic disruptions to local

residents

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BSM-Emulsion and BSM-Foam Ontario is Recycling!

o Total Ontario Annual Market Share ≈ 4-5 Million Sq. Meterso Municipal ≈ 2-3 Million m²; MTO ≈ 1-2 Million m²

o In 2015, MTO projects placed 30 (2-lane km) of FDR with Expanded Asphalt, 48 (2-lane km) of CIR (with Emulsified Asphalt) & 178 (2-lane km) of CIREAM (with Expanded Asphalt)

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In-Place Recycling Train alongside Live Lane

Foamed Asphalt – BSM-Foam

What Is It?How Does it Work?Curing and Strength DevelopmentPGAC

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Foamed Asphalt – BSM-FoamWhat is it?

o Mixture of damp, unheated aggregate and RAP plus hot liquid asphalt

o Mixed together while the asphalt is brought into a foamed stateusing water and air pressure.

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Laboratory Scale Foaming Test

Foamed Asphalt – BSM-FoamWhat is it?

o Bitumen and water are injected at high pressureo Foam created within expansion

chamber

o The physical properties are temporarily altered when the injected water makes contact with the hot bitumeno The water is explosively

transformed into vapor and trapped in thousands of tiny bitumen bubbles

o Foamed bitumen collapses quickly

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Production of Foam in Expansion Chamber

Foamed Asphalt – BSM-FoamWhat is it?o Expansion Decay Curve

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Dip Stick for Recording Measurements

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Foamed Asphalt – BSM-FoamFoam Properties?o Foaming properties of bitumen are characterized by:

o Expansion Ratio –Viscosity of the foamed bitumen,o Ratio of the maximum volume of the foam relative to the original volume

o Half Life –Stability of the foamed bitumen, o Time (seconds) taken in seconds for the foam to collapse to half of its maximum volume

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Plotting Expansion Ratio and Half Life on

the Same Graph

Foamed Asphalt – BSM-FoamFoam Quality

o Foam quality is dictated byo Bitumen

temperatureo Bitumen spray

pressureo Quantity of water

o Bitumen type has significant impact

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Foamed Bitumen

Foamed Asphalt – BSM-FoamFoam Quality

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PG Grades for Different Crude Oil Blend

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Foamed Asphalt – BSM-FoamHow Does it Work?o Dispersed bitumen forms a mastic (fines, bitumen and water) and

‘spot weld’ to larger aggregateo 75µm dust is required

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Mastic – Spot Welds

Dispersion of Foamed Bitumen Particles


o Foamed asphalt partially bonds with fines to form an asphalt mastic o visible in the loose mix as small droplets (a)

o Aggregate particles in the loose mix are mostly coated with a water membrane

o After compaction, the asphalt mastic droplets are in tight contact with the aggregate particles (b)

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Curing Process for Foamed Asphalt


o Water membrane prevents bonding to aggregates until moisture has evaporated (c & d)

o Curing : Combination of drying and particle contact allows bond to form.

o Rewetting of material not a concern unless aggregate moisture susceptible (e)

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Curing Process for Foamed Asphalt

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Full Depth Pavement Recycling

Ontario – OPSS 331 – Full Depth Reclamation with Expanded Asphalt Stabilization

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FDR – Full Depth Reclamation

o A full depth Reclamation / Reconstruction techniqueo Pulverizing and blending of the existing asphalt pavement and

underlying materials to a predetermined deptho Quality of the existing materials will dictate the strength of

the Mixo Strength of compacted foamed material higher than simple

pulverized pavement

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FDR – Considerationso Existing asphalt ~<150mm

o Limited by Equipment / cost

o Allows for profile correction

o Grader laid or paver laid

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Full Depth Reclamation with Expanded Asphalt

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Full Depth Reclamation Specificationo Full Depth Reclamation design standards and specifications are

outlined in OPSS 331

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Property OPSS 331

Trial Section Contractor may be approved to opt out or must give 48hrs notice prior to start

Acceptance QA

Min. Dry Tensile Strength 225 kPa

Min. Wet Tensile Strength 100 kPa

Min. Tensile Strength Ratio 50%

Min. Cure Before Wearing Surface

3 Days

Surface Tolerance OPSS 301

Compaction Avg. 97% of target density/ 5000m2 (OPSS 501). No measurement <95%

target density/ 5000m2

Gradation Envelope 100% passing 37.5mm sieve and 95-100% passing the 26.5mm sieve after

processing

Corrective Aggregate Shall meet OPSS 1010 requirements OPSS 331

Specifications

Emulsified Asphalt –BSM-Emulsion

What Is It?How Does it Work?Breaking and CuringUsesNotations

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Emulsified Asphalt – BSM-Emulsion What is it?o Comprised of bitumen, emulsifiers and watero The bitumen is dispersed in water in the form of an oil-in-water

type bitumeno Manufactured in specialized plants and has a shelf life of several

months in barrels, dependent upon storage techniques

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Bitumen in Water Emulsion

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Emulsified Asphalt – BSM-Emulsion What is it?

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Flows Easily at Room Temperature

o Emulsified asphalt is a low viscosity thick brown liquid o Low Viscosity → High Workability at Room Temperature

o Emulsified Asphalt Ingredients:o Asphalt

o Makes up 50% - 75% of the emulsion asphalt mixture

o Water o Free of particulate matter as it can adversely

affect performance or cause premature breaking

o Emulsifiero A surface active agent, or surfactanto Keeps the asphalt droplets in stable

suspension and controls the breaking timeo Also the determining factor in the

classification of the emulsion as anionic, cationic, or non-ionic

Emulsified Asphalt – BSM-Emulsion How Does it Work?o When mixed with aggregate, the charged emulsified bitumen

droplets are attracted to the oppositely charged aggregateo Material stabilized with emulsified bitumen is termed BSM-

emulsion

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o Used because it reduces asphalt viscosity for lower temperature uses

Emulsified Asphalt – BSM-Emulsion Breaking and Curing

o Emulsifier must be water soluble and possess a proper balance between hydrophilic (water-loving) and lipophilic (oil-loving) properties

o Breakingo To perform its ultimate function

as a binder, the water must separate from the asphalt phase and evaporate

o Separation → “breaking”

o Curingo Asphalt emulsion particles have

to coalesce (come together) and bond to the intended surface

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Relative Sizes and Distribution of Asphalt Particles in an Emulsion

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Emulsified Asphalt – BSM-Emulsion Uses

o Surface Treatmentso Spray Applied Seals; Chip Seal; Sandwich Seal; Sand

Seal; Dense-Graded Seal; Slurry Seal; Micro Surfacing; Cape Seal;

o Emulsion-Aggregate Mixeso Mixed-in-Place Process; Emulsion Central Plant Mix

(Cold); Emulsion Central Plant Mix (Warm) o Asphalt Pavement Recycling

o Cold Planning; Hot Recycling; Hot In-Place Recycling; Cold Recycling; Full-Depth Reclamation; “Cold In-Place Recycling”

o Additional Applicationso Tack/Bond Coat; Prime Coat; Crack Filling; Patching

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Emulsified Asphalt – BSM-Emulsion Notations

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HF–150PM

Partial Depth Pavement Recycling

Ontario – OPSS 335 – Cold In Place Recycled Expanded Asphalt Mix

Ontario – OPSS 333 – Cold In Place Recycled Emulsion Asphalt Mix

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Partial Depth Stabilizationo Partial Depth Stabilization designs

exist where thick layers of existing asphalt exist

o Partial Depth Reclamation is broken down into two design optionso CIREAM → Cold-In Place Recycled

Expanded Asphalt Mixo CIR → Cold In-Place with Emulsion

Asphalt

o Consists of entirely reclaimed/processed RAP

o Milled, crushed and mixed with stabilizing agents such as expanded or emulsified asphalt

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Partial Depth Recycling

Partial Depth Stabilizationo With expanded asphalt, the purpose is not to rejuvenate the

aged bitumen on the RAP. The tiny bitumen ‘splinters’ have sufficient heat energy to adhere to the aged bitumen, therefore a large amount of dust is not required for effective dispersion.

o With emulsified asphalt, the emulsion provides a coating on the aged asphalt particles and binds to the aged bitumen.

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Partial Depth Recycled Mat

Partial Depth Stabilization

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Property OPSS 335 – Expanded Asphalt OPSS 333 - Emulsion

Trial Section Contractor may be approved to opt out or must give 48hrs notice prior to start

Contractor may be approved to opt out or must give 48hrs notice prior to start

Acceptance QA QA

Min. Dry Tensile Strength 225 kPa n/a

Min. Wet Tensile Strength 100 kPa n/a

Min. Tensile Strength Ratio 50% n/a

Min. Cure Before Wearing Surface 3 Days 14 Days

Max. Allowable Moisture Before Wearing Surface

n/a 2%

Surface Tolerance No Deviations > 6mm No Deviations > 6mm

Compaction Min. 96% Min. 96%

Gradation Envelope 100% passing 37.5mm sieve and 95-100%passing the 26.5mm sieve after processing

100% passing 37.5mm sieve and 95-100%passing the 26.5mm sieve after processing

Corrective Aggregate Coarse shall meet OPSS 1003; Fine shall meet Superpave 19.0 binder course

Coarse shall meet OPSS 1003; Fine shall meet Superpave 19.0 binder course

Minimum Design Rate 1.0% 1.2%

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Partial Depth Stabilizationo Recycling can be achieved either:

o ‘In-Plant’ o ‘In-Place’

o The treatment option is dependent upon:o Existing pavement structure, Design requirements (construction

staging), Quality of material produced, Material Variability

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Partial Depth StabilizationCIREAM

o A rehabilitation technique involving:o Partial depth removal or milling of the existing asphalt pavement

layer, sizing and mixing with expanded (foamed) asphalt, relaying and compacting the cold bituminous material in one single operation

o Treatment depths ranging from 75mm to 125mm

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Partial Depth -CIREAM

Job Site Pictures –Partial Depth - CIREAM

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Partial Depth CIREAM – One Lane Complete

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Job Site Pictures –Partial Depth - CIREAM

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Partial Depth CIREAM – Two Lanes Complete


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Overhead View


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Overhead View

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Recycling Train


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Recycling Train


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Three Passes Complete

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Partial Depth StabilizationCIRo CIR is an rehabilitation method that mitigates reflective

crackingo The process is similar to that of CIREAM, however

Emulsified Asphalt is the primary stabilizing agent

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CIR Recycling Train

Partial Depth StabilizationCIR

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Must be Allowed to Cure

Mix Design

General Laboratory Procedures Wirtgen Cold Recycling Technology Asphalt Academy TG2

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Mix Design – BSM-FoamLaboratory Procedures / Guidelines

o Wirtgen Cold Recycling Technology – 2012

o Appendix A1.2 Mix Design Procedure for Foamed Bitumen Stabilization

o Appendix A1.3 Mix Design Procedure for Bitumen Emulsion Stabilization

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Wirtgen GmBH, Wirtgen Cold Recycling Technology,

Windhagen, Germany, (2012)

Mix Design – BSM-EmulsionLaboratory Procedures / Guidelines

Primary objectives:o Determine suitability of material

for Bitumen Stabilization

o Determine need for corrective additiveso Active Filler – Lime Cemento Corrective Aggregate

o Determine bitumen content

o Obtain an indication of the behaviour (engineering properties) of the stabilized material

o Wirtgen Manual Available at : http://www.wirtgen-group.com/en/service/search/?search=wirtgen+cold+recycling&lang=lang_en

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Wirtgen GmBH, Wirtgen Cold Recycling Technology,

Windhagen, Germany, (2012)

Mix Design – BSM-Foam & BSM-EmulsionGeneral Laboratory Procedures

o Asphalt Academy TG2

o Guideline for the Design and Construction of Bitumen Emulsion and Foamed Bitumen Stabilized Materials

o Available at www.asphaltacademy.co.za;

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Asphalt Academy; Technical Guideline: Bitumen Stabilized Materials; TG 2, 2nd Ed.,

May 2009

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Mix Design – BSM-Foam & BSM-EmulsionMix Design Levels

o Level 1 Mix Design (Baseline) *Wirtgen, TG2, and ONTARIO* o 100 mm diameter specimens (Marshall briquettes) are

compacted and cured for Indirect Tensile Strength (ITS) testing

o Level 2 Mix Design (Additional Confidence) * WIRTGEN and TG2*

o 150mm diameter by 127mm high specimens manufactured using vibratory compaction, cured at the equilibrium moisture content and tested for ITS

o Level 3 Mix Design (Additional Confidence) *WIRTGEN and TG2*o This procedure used triaxle testing on 150mm diameter by 300mm

high specimens for a higher level of confidence

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Mix Design – BSM-Foam & BSM-EmulsionMix Design Levels

o Wirtgen Manualo Design Level based

on ‘Additional Confidence’

o Asphalt Academy TG2o Increased Traffic

Volume

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Mix Design Flow chart from TG2

Mix Design Process–Foam & EmulsionAssess Suitability of Existing Materials

o Field Samplingo Each layer in the upper pavement

sampled separatelyo ±300mm typical but sample depth

should represent project requirementso Mass of Material Required for

respective tests

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Test Pit with Gas Powered Road Saw

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o For Unbound Pavement Materialso Granular base layers

o Standard Soil Testso Sieve analysis (ASTM D422)o Plasticity Index (ASTM D4318)o Modified moisture density relationship (AASHTO T-180)o Natural Moisture Content

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o Bound Pavement Materials – Aged Hot Mix Pavemento Cores / Saw Cuts / Project Pulverizedo Air Dried gradation of processed RAP

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o Standard Bituminous Testso Asphalt Extraction (ASTM D2172)o Asphalt Recovery and

Penetration (ASTM D1856, ASTM D5)

o Aggregate Gradation o Washed Extracted Aggregate


o Gradation (Sieve Analyses)o Plot Grading Curves against Target Curves

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Recommended Grading Curves

o Preliminary Indication of Strength

o Gradations varying from limits may not perform

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Mix Design Process–Foam & EmulsionEstimate Need For Active Filler

o Plasticity Index (PI)o Initial determination of need for hydrated lime or

cement

o Plasticity Index: >10o Pre-Treat Material with Hydrated Limeo Lime consumption determined using pH Test

o Plasticity Index <10o Carry out ITS without Fillero Ontario Method

o No guidance provided or mandatory filler use

o Wirtgen Suggests Active Filler should be used if TSR <60%

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Mix Design Process – BSM-FoamMix Moisture: Foamed Asphalt Mix

o Adjust material to correct moisture content prior to adding foam and mixing

o Wadd = 0.75WOMC –Wair-dry o Wadd – water to be added to sampleo WOMC – optimum moisture contento Wair-dry – water in air dried sample

o To minimize moisture loss, manufacture test specimens immediately after mixing.

o If immediate Compaction not practicalo Transfer foamed material into an

air-tight container and immediately seal

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Wirtgen WLB 10S Laboratory Scale Plant& Wirtgen WLM 30 Laboratory Pugmill Mixer

Mix Design Process – BSM-EmulsionMix Moisture: Emulsified Asphalt Mix

o Determining the amount of Water to add to achieve the Optimal Fluid Content (OFC):

o Mwater – mass of water to be addedo WOFC – optimum fluid content

determined by modified proctoro Wair-dry – moisture content of air dried

sampleo Msample – mass of sampleo Memul – mass of emulsion

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Wirtgen WLM 30 Laboratory PugmillMixer can be used for BSM-Emulsion

Mix Design

Fluid content = in-situ moisture + bitumen emulsion + water (%)

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Mix Design – BSM-FoamGeneral Laboratory Procedures – Level 1

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o Level 1 Mix Design *Ontario*o Level 1 Mix Design

utilizes Indirect Tensile Strength (ITS) tests on 100 mm diameter specimens to:o Indicate the optimum

bitumen content using ITSdry, and ITSwet and TSR.

o Select the active filler type and content using ITSwet and TSR.

Mix Design Flow Chart – Level 1 Highlighted

Mix Design – BSM-Foam & EmulsionGeneral Laboratory Procedures – Level 1

o Usually 4 Trial Design Rates Testedo Full Depth Reclamation

o 2.0% to 3.5% New Binder Application Rateo Partial Depth Stabilization

o 0.5% to 2.0% New Binder Application Rate

o Once curing is completed the briquettes are tested to determine

o Dry Tensile Strengtho Wet Tensile Strengtho Tensile Strength Ratio

o Strength Testing of BSM-Emulsion mixeso Wirtgen Procedure - Yeso Ontario specifications – No

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Busy Day of Tensile Breaks


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Typical Level 1 CurveBSM-Foam

Typical Level 1 Curve BSM- Emulsion

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Mix Design – BSM Foam & EmulsionGeneral Laboratory Procedures – Level 2

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o Level 2 Mix Design (Additional Level of Confidence)o Level 2 Mix Design utilizes the

Indirect Tensile Strength (ITS) tests on 150 mm diameter specimens.

o The ITS allows the binder content to be determined with increased confidence. The procedure uses the following tests:o Tensile strength at equilibrium

moisture conditions (using ITSequil).

o Tensile strength after moisture exposure (using ITSsoaked).


Mix Design – BSM-Foam & EmulsionGeneral Laboratory Procedures – Vibratory Hammer

o Vibratory Hammer Compactiono A laboratory compaction technique

emulates the particle orientation after rolling.

o gyratory and vibratory can be used to achieve 100% of Mod AASHTO T-180 density

o Vibratory hammer compaction is preferred to Modified AASHTO compaction

o For Level 1 mix designs where 100 mm diameter specimens are required, Marshall compaction may be used although gyratory maybe used as well.

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Mounted Vibratory Hammer Schematic

Mix Design – BSM-Foam & EmulsionGeneral Laboratory Procedures – Vibratory Hammer

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o How to Manufacture 150mm Specimen?o 2007 - ASTM D7328-07 Method A

o 152mm Diameter Mould

o Hammer Specifications:o Frequency = 3200 to 3500 beats per

minuteo Impact energy (manufacturers

rating) = 9.5 to 12 Jouleo Weight of hammer = 53 to 89N

excluding the weight of the tamper.

o Split moulds should be used for compaction of 150 mm diameter specimens.

Mounted Vibratory Hammer with Split Mould

A List of Potential Hammers with ASTM

Characteristics

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o Level 3 Mix Design (Additional Level of Confidence)o Level 3 mix design utilizes

triaxial testing to assess the shear strength of the BSM and the moisture resistance via the MIST apparatus.

o Values of cohesion, friction angle, and retained cohesion are determined for mix assessment



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o Triaxial Testo Obtain Cohesion

and Friction Angle Valueso Test 48 – 72

hours after completion of the curing procedure

o 150 mm Diameter and 300 ± 2 mm Height Specimen using Vibratory Hammer Compaction

Inside of Casing

Mohr Circle PlotHydraulic Loading Frame

Specimen on Base Plate


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o Retained Cohesion (MIST) (Moisture Induction Simulation Test) o Triaxial specimens are conditioned

with moisture exposure using the MIST apparatus.

o The method employs cyclic pursing of water pressure into specimen to simulate moisture induction of dynamic traffic in the field condition.

o Gives the most realistic simulation of pore pressuresgenerated in BSMs that have been exposed to water under traffic. And, therefore it gives the best assessment of mix durability.

MIST Device Features, Set-Up and Connections

Retained Cohesion Calculation

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Mix Design – BSM-Foam & EmulsionGeneral Laboratory Procedures – Curing

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o Curing Differences for 150mm Specimens used in Level 2 & 3 Designso To produce the

long-term equilibrium moisture content (~43-50% of OMC)

Curing Differs from the Level 1 (40°C for 72hrs then Half are Saturated to Determine the ITSwet and thus

the Moisture Susceptibility);

In Level 2 and 3, the 150mm specimens are used to determine ITSEquil which achieves Equilibrium

Moisture Content, and are compared with ITSSoak(24 hours at 25 °C)

Mix Design – BSM-Foam & EmulsionGeneral Laboratory Procedures – ITS Results

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o TSR used to identify problem materials. TSR is less than 50%, it is recommended that active filler be used.

o TSR less than 50%, and the ITSdryexceeds 400 kPa, likely to contain clays. In this situation, the material probably requires pretreatment. (pre-pulverizing)

Recommended BSM Classes Based on ITS Test

Results

Class 1 – High Shear Strength; Suitable for Base Layer Construction for Structural Capacity > 3 million ESALs

MTO Test Method LS-297

MTO Test Method LS-297 Lab Walkthrough

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Mix Design – BSM-Foam MTO Test Method LS-297

o In Ontario, BSM-Foam Specimens are manufactured according to MTO Test Method LS-297 R26o This method closely aligns with

manufacturing a 100mm diameter specimen according to Wirtgen A1.2.5.1 for BSM-Foam (i.e. Mix Design Level 1)

o Does not include Level 2 and Level 3 Mix Design

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Method of Test for the Determination of Indirect Tensile Strength of Expanded

Asphalt Mixes

Mix Design – BSM-Foam MTO Test Method LS-297

o Procedure for Preparing Lab Sampleo Manually screen the entire sample. Particles retained on the

26.5 mm sieve that are stuck together may be separated by hand

o Discard the material retained on the 26.5mm sieve

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Sieving Oversize Material

Mix Design – BSM-FoamMTO Test Method LS-297

o Procedure for Preparing Lab Sample

o Determine wlabsampleo Split 1000g sample and

determine moisture

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Determine Moisture Content of Mixtureo When wlabsample is less than 80% of

womc, determine the mass of water, mwater that that needs to be added to the remaining screened material as follows:

o mwater = (0.8 womc –wlabsample) x mlabsample

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o Reduce the prepared mix by splitting/quartering to get sufficient material to acheive a compacted height of 63.5mm ±2.5mm

o Approximately 1,100g per briquette

o Prepare 6 briquettes per AC content

Splitting / Quartering


o Procedure for Compaction of Specimens

o To achieve a compacted height of 63.5mm ± 2.5mm, usually 1,100g is sufficient for each briquette

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Determine Correct Amount of Material to Achieve 63.5mm Height



o To achieve a compacted height of 63.5mm ± 2.5mm, usually 1,100g is sufficient for each briquette

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Determine Correct Amount of Material to Achieve 63.5mm Height

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o Using the spatula, rod the prepared mix in the mold 25 times – 15 around the outside, 10 around the centre

o When rodding around the inside, do not change direction of the blade, and finish by leaving a small cone of prepared mix in the centre of the mold

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Rod the Prepared Mix



o The briquettes shall be compacted at room temperature

o Each briquette shall receive 75 blows per side. Make sure hammer is kept as vertical as possible and ensure free fall of the hammer during compaction

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Marshall Hammer 75 Blows per Side


o Procedure for Curing the Specimens

o After compaction, allow the specimen to cure for 24 hours in the mold in a force draft oven at 40°

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o Allow the molds to cool until warm to touch, and extrude the briquettes by means of an extrusion jack

o Place extruded samples on their faces on a smooth flat tray and cure in a forced draft oven for a further 48±4 hours at 40°C

40°C Oven

Extrude After 24hr

Curing

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o Procedure for Curing the Specimens

o Allow the briquettes to cool in air at room temperature for a minimum of 4 hours and a maximum of 20 hours

o The use of fans or other methods of accelerating cooling of specimens is not permitted

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Cool in Air


o Procedure for Determination of Direct Tensile Strength

o When cooled, the diameter, d (mm) and the height, h (mm) around the circumference at 4 evenly spaced places shall be measured for each briquette to calculate average height (have)

o V = π r2 have/1000o D=M/Vo Group the 6 briquettes into two (2) sets of three (3) so that the

average density of each set is essentially the same

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Measurements



o Bring the dry specimens to the test temperature of 25°C by placing the briquettes in a dry temperature control system at 25±1°C for at least 1 hour, but not for longer than 2 hours before testing

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Incubator at 25°C

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o Condition the 3 briquettes in a wet temperature control system under minimum 25mm of distilled water for 24 hours OR covered with water at 25°C±1°C place in 50mm mercury vacuum for 60±1 min

o Determine Tensile Strength of all wet and dry cured samples

o ITS = 2000P/ π haved

o TSR = ITSwet / ITSdry x 100%

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Covered with Water in a Vacuum

Tensile Break with Pine Machine

MTO Test Method LS-300

MTO Test Method LS-300 Cold Mix Design Inconsistencies

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Mix Design – BSM-EmulsionMTO Test Method LS-300

o In Ontario, BSM-Emulsion Specimens are manufactured according to MTO Test Method LS-300 R29 (New 2015)

o This method differs with manufacturing a 100mm diameter specimen according to Wirtgen A1.3.5.1 for BSM-Emulsion (i.e. Mix Design Level 1)

o Method does not mention manufacturing 150mm Diameter Specimens (i.e. Mix Design Level 2 and Level 3)

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Method of Test for Preparation of Marshall Specimens for Cold In-Place

Recycled Mixtures

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Procedure MTO Test Method LS-300 Wirtgen A1.3.5.1

Pre-heat Aggregate Sample Prior to Mixing

40±3°C for not more than 1 hour prior to mixing

N/A

Optimum Fluid Content (OFC)

Assumed to be 4.5%4.5% liquid = % emulsion + % water remaining in the air dried

sample + % water added

Determine the amount of water to be added to achieve

the OFC of the material

Mixing Thoroughly mixed by hand. Wirtgen WLM 30 pugmill mixer

Preheat of Moulds 40 ± 3°C N/A

o There are Differences with MTO Test Method LS-300 and Wirtgen Specimen Manufacture


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o Previous revision of MTO Test Method LS-300 involved curing for 72 hours at 60°C. That curing procedure was prone to yielding target densities that were unachievable in the field.

Comparison of 25°C, 40°C & 60°C Curing (BSM-Foam briquettes are shown)

Mix Design – BSM-EmulsionCold Mix Design Inconsistencies

111

o As discussed previously, the procedures to select the design rates for BSM-Foam or BSM-Emulsion using Wirtgen Appendix A1.2 and Appendix A1.3 treat the two materials very similarly(Not the case in Ontario!)

o What is Ontario’s selection process for optimum BSM-emulsion design rates?o Nearly all dense-graded cold mixtures use a method that is a

modification of Marshall design methods

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o Basic Asphalt Emulsion Manual, MS-19, 4th Editiono This manual standardizes two design

methods for use with asphalt emulsion cold mixtureso dense-gradedo open-graded

o Dense Graded Aggregate Cold Mix Design:o Determine bulk densityo Other volumetrics such as voids, voids

filled and voids in mineral aggregate may be determined

o A stability value of 500 pounds (2224 Newtons) or greater has been found to be satisfactory for most pavements with low to moderate traffic volumes

o Methods do not mention ITS Testing!

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4th edition of MS-19, The Basic Asphalt Emulsion Manual; The Asphalt Institute

(AI) and the Asphalt Emulsion Manufacturers Association (AEMA)


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AI Method - Modification of the Marshall Method (Shown Above)

Stability – Min. 2224 N (lb) at 22.2°CPercent Stability Loss - Max. 50Aggregate Coating – Min. 50%

Typical Emulsified Asphalt-Aggregate Mix Design Plots


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o Observations:

o In Ontario, the OPSS 333 Specification is more lenient than OPSS 335 or OPSS 331 in terms of acceptance criteria for strength properties

o These mixes should be treated similarly in terms of expected strengths according to Wirtgen & TG2

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pAdditives to Enhance Mix Design Properties

Virgin Aggregates, RAP, Cement , Lime, Fly Ash, & Additives to Asphalt Cement

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Additives to Enhance Mix PropertiesWhy do We Need Additives?

o Certain granular base materials adversely effect cold recycle mixeso Shaleo Sando Clayo Silt

o Use of additives can reverse the negative effects and increase tensile strength and tensile strength ratio

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Additives to Enhance Mix PropertiesWhat are the Additives?

o Virgin Aggregateso Stone (ex. HL3)o Granular Ao Screenings

o RAPo Cement o Limeo Fly Asho Additives to Asphalt Cement

o May result in increased strengthso Better dispersion and foaming propertieso Cost effectiveo Easy to Implemento i.e. no extra labour

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Additives can be Added Directly to the Asphalt Cement

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Additives to Enhance Mix PropertiesThe Use of Additives

o Additions of RAP or Virgin aggregates to mix can:o Correct gradation envelope o Reduce AC addition when RAP is usedo Improve strength

o Increasing amount of material below 0.075mm can: o Improve bitumen dispersiono Improve workabilityo Improve strength

o Augmenting AC with additives can: o Aid in better cohesiono Improve foaming propertieso Improve strength

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Corrective Aggregates may Improve Mix Properties


o Portland Cemento Increase free fines content of mixo More effective dispersion of foamo Cementitious effect (hydration

process)

o Fly Asho Increase free fines content of mixo More effective dispersion of foam

o Limeo Increase free fines content of mixo More effective dispersion of foamo Reduces stripping

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Caution: Additives are Easily Added in Laboratory Setting; Not as Easy to Incorporate during the Construction

Operation


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Incorporating Cement Ahead of the Recycling Train

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Incorporating Hydrated Lime Ahead of the Recycling Train


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Incorporating Hydrated Lime Ahead of the Recycling Train


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Placing RAP

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Placing RAP

Additives to Enhance Mix PropertiesAdditive Conclusions

o Additives can be a very beneficial tool o Identify what options are

available to target specific weaknesses during the design stage

o Refrain from ‘Rule of Thumb’ designso Each project is uniqueo Materials constantly change

even in similar locations

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Caution: Cement >1%, Hydrated Lime >1.5%; The Increase in Mix Stiffness is Compromised Significantly by a Loss in Flexibility of the material. Takes Away

the Benefits of Bitumen!

In-Place Recycling Construction

Profile Milling, Pre-Pulverizing Paver Compaction Equipment

126

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In-Place Recycling ConstructionProfile Milling (CIREAM / CIR)o Profile Milling allows for:

o Shape correction of profileo Removal of in-situ materialo Isolation and correction of high spotso Reduce depth of distressed asphalt below the recycled layer

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In-Place Recycling ConstructionProfile Milling

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Partial Depth Asphalt Removal

o Restore Cross-fall?o Milling for profile and/or cross-fall

In-Place Recycling ConstructionProfile Milling

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Profile Milled (left)

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In-Place Recycling ConstructionPre-Pulverizingo Re-Profile?

o Pulverization, grade, compact, import material if required

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Full Depth JobCutting

Drum

CL

2% - Variable

In-Place Recycling ConstructionPavero Heavy Duty Vogele Paver with High Density Screed

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Tamping Bar and Pressure Plates

In-Place Recycling ConstructionPaver

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Ultrasonic Ski for

Longitudinal Profile

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Automatic Grade controls


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Discharge to Hopper


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Windrow

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In-Place Recycling ConstructionCompaction Equipmento Compaction effort is applied to the recycled material immediately

by a heavy vibrating roller o Amplitude setting changes the compaction efforto Frequency setting changes the depth of penetration

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Steel Drum Roller

In-Place Recycling ConstructionCompaction Equipment

o Water is added periodically to maintain optimum moisture content

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Adding Water (for BSM-

Foam)

A Pneumatic-Tired Roller is Used to Achieve Final

Compaction

Field Quality Testing

Compaction Testing, Control Strips and using a Nuclear Moisture Density Gauge

In-Situ Sampling

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Quality Control Procedures Compaction Testingo 96% (Min.) for CIR and CIREAM Based on target Bulk

Relative Densitieso 97% (Min.) for FDR with EA Based on field control strip

(OPSS 501)

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Fresh Mat Behind Paver

Quality Control Procedures Compaction Testing

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Nuclear Moisture Density Gauge

o Nuclear Moisture Density Gaugeo In Ontario, used for compaction acceptance in OPSS 331

(treated more like a granular) not for acceptance in OPSS 333 or OPSS 335

Quality Control Procedures –Nuclear Moisture Density Gauge

o Compaction is monitored with a Nuclear Moisture Density Gaugeo Inaccurate moisture

measurements due to presence of hydrocarbons (bitumen)

o ‘K-Value’ setting is used to offset the hydrocarbons present

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Nuclear Moisture Density Gauge

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Quality Control Procedures In-Situ Sampling

142

o Bulk samples (approx. 20kg) are normally taken from behind the recycler, at least one per 5000m2 of pavement recycled

o Sealed to prevent moisture losso One sample BEFORE binder

additiono One sample AFTER binder

addition

Loose In-Situ

Field Sample

Representative Sample Required

Quality Control Procedures In-Situ Sampling

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o The samples are used to determine:o Application rate of the stabilized materialo Moisture contento Bulk relative density and tensile strength

from manufactured briquette specimens (LS-297)

o Wirtgen Appendix A1.4o Field Samples are to be transported to

the laboratory within two hours of sampling and the test specimens manufactured within four hours of being sampled

Sealable Bags

Timely Testing

Laboratory Testing QC/QA

Production Samples Post-Production Samples

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Quality Control Procedures –Laboratory Testing

o Extraction/ Ignition Testing o Pre-Stabilized → Initial Asphalt

Cement Contento Stabilized → Final Asphalt Cement

Content

o The difference in %AC is then compared with the Mix Design

o Particle size distributions are also determined and compared with the mix design

145

Ignition

Extraction


o Marshall briquettes are produced according to LS-297 from the loose stabilized field samples

o Tensile strengths and densities of the lab produced samples are compared to the min. requirements as per OPSS standards

146

Curing Production Samples Strength Verification Testing


o Post-Production Saw-Cut Samples (CIREAM and CIR)o Dry Cut 150 x 150 mm and removed intact from the mat.o One slab sample shall be used to test for bulk relative density and

the other slab sample shall be used to test for moisture content

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Bulk Specific Gravity and Density of Compacted Bituminous Mixtures Using Automatic Vacuum

Sealing MethodDetermine Moisture Content of

Post-Production Sample

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148

Bulk Specific Gravity and Density of Compacted Bituminous Mixtures Using Paraffin Coated Specimens

Project Experience

Issues and Challenges

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Project ExperienceIssues and Challenges

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Rain Delays

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151

No Confined Edge for Compaction


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Accelerating Curing Using Infrared Heaters


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Break through in CIREAM

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Segregation


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Ravelling


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Ravelling

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Rutting and Flushing


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Rutting


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Tight Working

Areas

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Tapers, Small Areas


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Recycler Width


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Additives - Logistics

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Additives - Logistics


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Additives – 19mm Crusher Run Limestone


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Additives – 19mm Crusher Run Limestone

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Night Work


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Night Work


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Night Work

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169

Construction Joints


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Existing Conditions –

Super Elevation


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Existing Conditions – Cross-fall / Super Elevation

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Urban Work -Catch basins


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Traffic Staging


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Post Milling to Correct

Smoothness Prior to Overlay

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You know there is a rush on lab testing when you receive pavement samples in suitcases!

DISCUSSIONDISCUSSION

2015 ctaa course november 15, 2015 final as presented · 2015-11-15 · 11/15/2015 2 pavement...

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