Asphalt Quality Assurance Program & Construction Inspection - - PowerPoint PPT Presentation

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Asphalt Quality Assurance Program & Construction Inspection - - PowerPoint PPT Presentation

Nov 15, 2023 13 likes •527 views

Asphalt Quality Assurance Program & Construction Inspection 2015 Asphalt Regional Seminars Rob Crandol, P.E. Trenton Clark, P.E. VDOT Materials Division Virginia Asphalt Association Assistant State Materials Engineer Director of

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Asphalt Quality Assurance Program & Construction Inspection

2015 Asphalt Regional Seminars

Rob Crandol, P.E. VDOT – Materials Division Assistant State Materials Engineer Trenton Clark, P.E. Virginia Asphalt Association Director of Engineering

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QUALITY ASSURANCE

QUALITY CONTROL (QC) and ACCEPTANCE INDEPENDENT ASSURANCE (IA) VERIFICATION SAMPLING AND TESTING (VST)

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Are these Actually Different?

QA or Quality Assurance is the overall program required by the owner.

  • 1. QC or Quality Control is the processes*/procedures

used by the contractor.

* These processes are beyond the minimum requirements of acceptance testing - such as additional sampling

Acceptance is the procedure for which a product is measured for adherence to specification such as mat

  • density. In Virginia, this procedure is performed by

the contractor for asphalt

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Are these Actually Different?

  • 2. Independent Assurance is a procedure/process used

by the owner.

The purpose is to ensure the people, equipment, and procedures used by the Contractor are compliant to specification

  • 3. Verification, Sampling and Testing is a procedure /

process used by the owner.

The purpose is to check the acceptance decision by the Contractor such as verification cores

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VDOT Uses System & Project Approach to QA

System Approach at the Plant (Contractor)

  • Certified technicians
  • QC on mixes during production
  • Sampling for acceptance on AC Content and

Gradation; Pass/Fail on Volumetrics

  • All mixes going to VDOT projects tested, but not

specific to a project

  • Test data entered into PLAID
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VDOT Uses System & Project Approach to QA

System Approach at the Plant (VDOT)

  • Certified technicians
  • Mix samples collected for statistical comparisons on

AC Content and Gradation

  • Mix samples collected with contractor acceptance

samples for IA (matched samples)

  • VDOT samples compared to other contractor

acceptance samples for VST (unmatched samples)

  • VDOT volumetric samples collected for Pass/Fail only

and compared to contractor results

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Asphalt Plant Quality Control

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VDOT Uses System & Project Approach to QA

Project Approach in the Field (Contractor)

  • Asphalt Field Level 2 Technician
  • Certified density technicians
  • Establish roller pattern and control strip
  • QC on density during compaction of Lots
  • Acceptance on Lot mat density
  • Monitoring of longitudinal joint density
  • All data recorded on TL forms and provided to VDOT
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VDOT Uses System & Project Approach to QA

Project Approach in the Field (VDOT)

  • Asphalt Field Level 2 technicians
  • Monitor construction of roller pattern
  • Monitor compacting, nuclear density testing, coring/plug

and calculation of average control strip density

  • Randomly tests cores from control strip (IA)
  • Provides random numbers to contractor
  • Monitors nuclear density testing in Lot
  • Identifies and retrieves cores for VDOT acceptance testing

(VST)

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VDOT Project Staff Responsibilities IA

  • Verifies paving equipment meets specifications
  • Verifies materials being used are from approved

sources

  • Take temperature measurements of AC at least every

hour

  • Verifies that contractor personnel are performing QC
  • perations correctly
  • Verifies density testing being performed
  • Joint Density

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VDOT/Materials VST and IA

  • Perform VST testing on plugs
  • IA testing
  • Verify method of random selection
  • Marking of test locations
  • Observe QC testing at control strip
  • Observe test sections.
  • Obtain samples of cores from control strip to reweigh

in laboratory.

  • Depth Control tests

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So where does construction inspection fit into VDOT’s QA Program ?

QUALITY ASSURANCE

QUALITY CONTROL (QC) and ACCEPTANCE INDEPENDENT ASSURANCE (IA) VERIFICATION SAMPLING AND TESTING (VST)

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Construction Inspection VDOT Representatives (consultant or VDOT employee) provides the construction oversight & inspection Representatives must be familiar with the VDOT Road and Bridge Specifications as well as Special Provisions that are found in the contract.

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Document Hierarchy Section 105.12

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Standard Drawings Standard Specifications Supplemental Specifications Plans Special Provisions Special Provisions Copied Notes

General notes and other written information not in a SP or SPCN in No Plan and Minimum Plan Concept contracts carry the same weight as plans

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Key Inspection Points

Prior to Density Acceptance

Site preparation Milling Tacking Equipment Placement Compaction

Density Acceptance

General requirements Small quantity applications VTM-76 QC test sections Independent assurance Verification testing and sampling Referee procedure

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Site Preparation

Areas of particular concern/focus:

  • Repairing failed areas
  • Cleaning the surface
  • Tack-achieve bonding of layers

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Site Preparation – Failed areas Not addressing failed areas leads to premature failure of

  • ur overlays & resurfacing

Approaches to correct failures can include:

  • Milling
  • Patching prior to the contract for resurfacing
  • Specify patching type, material and locations in

the contract

  • Use Special Provision (SP) for Surface Preparation and

Restoration Prior to Plant Mix Overlay (Volume 2)

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Milling

Why mill a road?

  • Remove material distress
  • Maintain surface elevation
  • Improve cross-section

What things must be inspected?

  • Presence of scabbing
  • Positive drainage
  • Cleanliness
  • Performance milling
  • Time frames
  • Run-on conditions

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What Happens with No Bonding

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½” Deflection, 60# Load ¼” Deflection, 160# Load Fully Bonded Unbonded Bonded Demonstration

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Cores Showing Debonding

Bonding Failures

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Days later!

Courtesy of Road Science

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Tacking – Proper Mainline

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Tacking – Mainline and Joints

What two categories of tack coat materials are approved by VDOT?

  • Conventional Tack – Section 310
  • Non-Tracking Tack Coat –Volume 2

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Tacking – Mainline and Joints

What is the specified application rate for conventional tack on mainline? Where is it found?

  • 0.05 – 0.10 gal/sy for undiluted

Section 310.03

What is the specified application rate for non- tracking tack coat on mainline?

  • Rate recommended by the manufacturer

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Tacking – Longitudinal Joints Proper application to result in joint density Width of application for first paving pass?

  • 2 feet – 18 to 20 inches under first pass, 4 to 6

inches protruding beyond first pass

  • For second pass, vertical face of first pass and

approximately 1 foot into lane to be paved

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Equipment

Material Transfer Vehicle

  • Required for interstate surface paving in 2015
  • Required for SMA and other specialty mixes
  • Minimum 15 ton combined capacity between

device and paver paver hopper

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Placement

Temperatures

Base

  • WMA: 40F minimum
  • HMA: 40F for “A” mixes and less 25% RAP; 50F for “A” mixes

and 25% or more RAP, “D” and “E”

Mix

  • Maximum is 350F or specified by liquid supplier
  • New for 2015: WMA minimum is 200F

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Placement

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Paver Items

Longitudinal joints must be offset 6” from underlying joint Surface longitudinal joint must be 6” – 12” from centerline marking; 6” offset from between lane markings Continuous line for steering the paver Grade control with ski, joint shoe

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Density (Compaction)

CRITICAL to pavement durability & performance ! No significant changes to procedures from 2014 SMA changes: Allow more than 3 vibratory passes, caution not to crush the stone

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Roller ller pa pattern ttern

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2 3

50 FEET 75 FEET MARK TEST LOCATIONS ORIENT GAUGE IN SAME DIRECTION

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Thin Lift Roller Pattern Graph TL-57

2 3 4 5 6 7 8 143 142 141 140 139 138 137 136 135

Density lbs/ft3 Roller Passes

Maximum Density = 142.5 lb/ft3

Roller Pattern = 5 passes 3 Vibratory 2 Static

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Control Strip Construction

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  • Establishes an average nuclear

density reading (10 locations)

  • Verifies nuclear density

reading using asphalt cores

  • Determines the Target Density

Value for subsequent acceptance testing

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When do you have to construct a Control Strip?

VDOT specifications require that one control strip be constructed at the beginning of work on each roadway and shoulder course and on each lift of each course.

Control Strip Construction

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Locations of nuclear readings are marked by contractor.

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Core locations are marked for cutting.

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Verification of Target Density

Mix Type Min.Control Strip Density% SM-9.5A, SM-12.5A 92.5 SM-9.5D SM-12.5D 92.2 SM-9.5E, SM-12.5E 92.2 IM-19.0A, IM-19.0D, IM-19.0E 92.2 BM-25.0A, BM-25.0D 92.2

Table III-3

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Control Strip Construction

An additional control strip is required when:

  • There is a change in type or source of materials.
  • There is a significant change in the composition of

the material being placed from the same source.

  • There is a control strip failure (consecutive failures?)

Construction must cease if new control strip is required

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Test Sections

Table III-4 Payment Schedule for Lot Densities % of Target Control Strip Density Percent of Payment Greater than 102.0% 95 98.0 to 102% 100 97.0 to less than 98.0% 95 96.0 to less than 97.0 90 Less than 96.0% 75

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SM-4.75 is Slightly Different

Mix monitored at plant through permeability testing as well as standard tests In the field:

Roller pattern established (same as other dense graded mixes) Control strip constructed

  • BUT NO CORES
  • Average nuclear density from 10 readings is target

Lot testing and payment follows Table III-4

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