Quality Control & Quality Assurance In Road Construction

By Superintending Engineer, TVCC, BBMP 1

BBMP Quality Control : Several lakhs of rupees being spent for Infrastructure and other Improvement works in BBMP. In order to ensure quality of works a full fledged, well equipped in house laboratory is necessary. Presently the BBMP has a quality control wing constituting EE’s , AEE’s & AE’s. The quality control lab is equipped for testing cement, sand, metal, bitumen, bituminous mix, etc., The field Engineers shall make use of BBMP quality control lab to ensure good quality works. 2

Emplaned Laboratories in BBMP The BBMP has emled consultants / firms having material testing laboratories. The agency has to make its own arrangement to convey the samples to the laboratories for testing .

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Quality Control Tests Necessary to Control a Product Determine Quality of Product being Produced Performed by Contractor

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Quality Assurance Tests Necessary to Make a Decision on Acceptance Ensure Product being Evaluated is What the owner Specified Performed by Owner

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Quality Control vs. Quality Assurance • Quality Control (QC) = The contractors system in place during the construction to manage, control and document his activities in order to comply with contract requirements

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Quality Assurance (QA) = The Governments system in place to monitor the Quality Control efforts of the contractor

QC + QA =

High Quality Finished Road

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3 Phases of Contractor Quality Control

A PR

MA Y

JUN

JUL

A UG

S EP

OCT

NOV

Cl e a r a n d G r u b Ex c a v a t Io n S u b - b a s e B a s e P r e p.

Preparatory Phase

Start-up Phase

Production Phase 7

3 Phases of Contractor Quality Control What is involved? Preparatory Phase •Review Plans and Specs • submittal approval •Check preliminary work •Examine materials •Discuss construction methods •Review Safety •Coordinate surveying and staking work

Start-up Phase •Establish quality required •Resolve conflicts •Ensure testing is performed •Establish detailed testing schedule based on production schedule •Review Safety

Production Phase •Ensure Contract Compliance •Conduct intermittent or continuous inspections to identify and correct deficiencies •Inspect completed phases before scheduled Government acceptance •Ensure Testing reports are submitted •Ensure rework is completed 8

CONSTRUCTION PHASE-Quality Control

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Requirements Ensure Quality Create Durable National Assets Grossly Inadequate for Present day Needs

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Advantages Improved Quality Uniformity Economic Utilisation of Materials Reduction in Cost Extra Cost – Fraction of Resulting Benefits ½ to 1% of Construction Cost Economic Return – 5 – 10% of Total Construction Cost

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Pre Pre--requisites Provision for Quality Control in Construction, Specification and Estimates Adequately Trained Staff Adequate Equipment Periodic Appraisal of the QC Data Updating of Knowledge by On-job Training

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Quality Control In Road Construction Control of Materials Test Procedure Frequency and Extent of Testing Acceptance Criteria Equipment Type & its Calibration Recording of Test Results Training for QC 13

Quality Control Test Individual Materials

Soil, Gravel, Aggregate, Binder

Mixes Gradation of Aggregates, Mix Proportion, Mixed Design Properties

During Construction Process Spreading Segregation Temperature – Mixing, Laying, Rolling

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Quality Control Test Test on Compacted Layer Mixed Proportion (Unbound Layers) Density Mix proportion and Gradation (bound layers after extraction)

Finished Surface Longitudinal Profile Transverse Profile Cross Slope Texture

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Tests On Borrow Materials Of embankment/subgrade Test

Min. Desirable Frequency

Gradation/ Sand Content

1-2 Tests per 8000 m3 of Soil

Plasticity Index

1-2 Tests per 8000 m3 of Soil

Standard Proctor Test

1-2 Tests per 8000 m3 of Soil

CBR on a set of 3 Specimens Deleterious Constituents

One Test per 3000 m3

Natural Moisture Content

One Test per 250 m3 of Soil

As Required

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Density Requirements Of Embankments And Subgrade Embankments upto 3 metres height, not subjected to extensive flooding Embankments exceeding 3 metres height or embankments of any height subject to long periods of inundation Subgrade and earthern shoulders/ verges/backfill

Not less than 15.2 kN/cu.m

Not less than 16.0 kN/cu.m

Not less than 17.5 kN/cu.m

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Compaction Requirements For Embankment And Subgrade Type of Work/ Material Subgrade and Earthen Shoulders Embankments

Relative Compaction as % of MDD Not less than 97 Not less than 95

Expansive Clays: Subgrade and 500 mm portion just below the subgrade Remaining Portion of Embankment

Not Allowed

Not Less than 90 18

Frequency of Compaction Tests Particulars

Frequency (min)

Moisture Content prior to compaction

One test for every 250 m3 of soil subject to min. of 4 tests/day

Thickness of layer

Regularly

Degree of compaction (a) Body of embankment

At least one test per 1,000 m2 for each layer

(b) Subgrade and shoulders

At least one test per 500 m2 for each layer

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Location Of Density Test Points For Earth Work

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Acceptance Criteria Control should be based on the mean value of a set of 55-10 density measurement. The criteria for acceptance shall be subject to the condition that the MEAN DENSITY is not less than the specified density plus: plus:   1.65 1.65 − (No. of samples)0.5  times the standard deviation  

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Granular SubSub-base Gradation

One test per 200 m3

Atternberg limits

One test per 200 m3

Moisture Content prior to One test per 250 m3 Compaction Density of Compacted One test per 500 m2 Layer Deleterious Constituents As Required CBR

As Required 22

Lime/ Cement Stabilised Soil SubSub-base

Quality of Lime/ Cement

Lime/Cement Content

One Test for Each Consignment Subject to a Minimum of one Test per 5 Tonnes Regularly, through Procedural Checks

Degree of Pulverisation

1-2 Tests per 8000 m3 of Soil

CBR or UCC

As Required

Density

One Test per 500 m2 23

Physical Requirements Of Coarse Aggregates For Water Bound Macadam For SubSub-base/base Courses

Test

Requirements

Los Angeles Abrasion Value

40 percent (Max.)

or Aggregate Impact Value

30 percent (Max.)

Combined Flakiness and Elongation Indices

30 percent (Max.) 24

Water Bound Macadam Aggregate Impact Value Grading Flakiness Index and Elongation Index Attenberg Limits of Binding Material Attenberg Limits of Portion of Aggregate ing 425 micron sieve

One Test per 200 m3 of Aggregate One Test per 100 m3 One Test per 200 m3 of Aggregate One Test per 25 m3 of Binding Material One Test per 100 cubic Metre of Aggregate

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Wet Mix Macadam Aggregate Impact Value

One Test per 200 m3 of Aggregate

Grading

One Test per 100 m3 of Aggregate

Flakiness and Elongation Index Attenberg Limits of Portion of Aggregate ing 425 micron sieve Density of Compacted Layer

One Test per 200 m3 of Aggregate One Test per 100 m3 of Aggregate One Test per 500 m3 26

Prime Coat / Tack Coat Quality of Binder

Two Samples lot to be subjected to all or some Tests as Directed by the Engineer

Binder Temperature for Application

At Regular Close Intervals

Rate of Spread of Binder Two Tests per Day

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Surface Dressing Quality of Binder

Two Samples per lot

Aggregate Impact Value

One Test per 50 m3 of Aggregate

Flakiness Index and Elongation Index

- do -

Stripping Value of Aggregates Water Absorption of Aggregates

3 specimens per source

Grading of Aggregates

One Test per 25 m3 of Aggregates

- do -

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OpenOpen-graded Premix Carpet/ MixMix-seal Surfacing Quality of Binder

Aggregate Impact Value FI and EI of Aggregates Stripping value

Two Samples per lot to be Subjected to all or some tests as Directed by Engineer One test per 50 m3 of Aggregates - do 3 specimens per source

Water Absorption of - do Aggregates Grading of Aggregates One Test per 25 m3 of Aggregates 29

Physical Requirements Of Aggregates For Bituminous Macadam Test

Requirement

Los Angeles Abrasion Value FI and EI

40 % Max.

Coating and Stripping of Bitumen Aggregate Mixtures Soundness

30 % Max.

12 % Max.

Water Absorption

2 % Max.

30 % Max.

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Bituminous Macadam Quality of Binder

Aggregate Impact Value FI and EI of Aggregates Stripping Value Grading of Aggregates

Two Samples per lot to be subjected to all or some tests as directed by the Engineer One Test per 50 m3 of Aggregate - do 3 specimens per source Two Tests per day per plant both on the individual constituents and mixed aggregates from the dryer 31

Bituminous Penetration Macadam/ BuiltBuilt-up Spray Grout Quality of Binder

Two Samples per lot to be subjected to all or some tests as directed by the Engineer Aggregate Impact Value One Test per 200 m3 of Aggregate FI and EI of Aggregates - do Stripping Value

3 specimens per source

Aggregate Grading

One Test per 100 m3 of aggregate At regular Close Intervals

Temp. of Binder at Application

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Requirements For Semi-dense Bituminous Concrete Mix Marshall Stability

820 kg (1800 lbs) Min.

Marshall Flow

2-4

Percent Air Voids in Mix

3-5

Percent Air Voids in Mineral Aggregate (VMA) Minimum Percentage Air Voids in Mineral aggregates filled with Bitumen (VFB) Binder Content, percent by weight of mix

1313-15 6565-75

Not less than 4.0 percent

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Dense Bituminous Madacam/ Semi Dense Bituminous Concrete/ Bituminous Concrete Quality of Binder

Aggregate Impact Value F I and E I of Aggregates Stripping Value Water Absorption of Aggregates Water Sensitivity of mix

Two Samples per lot to be subjected to all or some tests as directed by the Engineer One Test per 50 m3 of Aggregate One Test per 50 m3 of Aggregate 3 Specimens per Source - do As Required for BC 34

Requirements Of Bituminous Concrete Mix Marshall Stability

900 kg Min.

Marshall Flow

2-4

Percent Air voids in Mix

3- 5

Min. VMA Percent related to Design Air Voids, %

3.0 - 10-14 % 4.0 - 11-15% 5.0 - 12-16 %

Percent Airvoids in Mineral Aggregates filled by Bitumen (VFB)

65 - 75

Binder content percent by weight of total mix

5- 6 (50 (50--65 mm thick) 5 - 7 (30(30-45 mm thick)

Water Sensitivity

Min. 75 % Retained Strength

Swell Test

1.5 % Max. LAV

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Testing Of Asphalt Mixes

Aggregate gradation Asphalt content Temperature Theoretical maximum density In In--place density Smoothness Visual inspection 36

Aggregate Gradation

SAMPLING • • • •

STOCK PILE COLD FEEDER BELT HOT BINS EXTRACTED ASPHALT MIXTURE (END PRODUCT)

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Trouble Shooting

Sampling stock pile Check gradation of new material added Segregation in feeder belt Improper loading of cold bins Improper setting of individual bins

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Asphalt Content

Important for satisfactory performance Low asphalt contentcontent- less durable mix More asphalt contentcontent- not stable mix Affects film thickness, voids, stability and flow

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Temperature



High enough to provide good coating on aggregates Allow satisfactory compaction More heating – additional oxidation, loss of volatiles, reduce mixture durability

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Temperature Grade

Bitumen

Agg.

Mix

Rolling Laying

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150 - 165 150 - 170 165 Max 90 Min 125 Min

90

140 - 160 140 - 165 155 Max 80 Min 115 Min

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Compaction







Commence From Edges And Progress Towards Centre Initial Breakdown Rolling – 8 To 10 T Smooth Wheel Roller Intermediate Rolling – 8-10 T Dead Wt. Or Vibratory Roller.Pneumatic Tyred Roller –12 12--15 T Wt. 5.6 Kg/Sq.Cm Pr. Finished Rolling – 6-8 T Smooth Wheel Tandem Roller 42

Compaction

Roller Speed Not More Than 5 Kmph



Do Not Permit Rollers To Stand On Pavement



Prevent Oil Drop



Keep Wheels Just Moist Enough

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Suggested Frequency And Amplitude For Vibratory Compaction Nature of Soil/ Materials

Rock

Frequency (M)

Amplitude (mm)

Thickness of Compaction, mm

1800 1800--2500

1.2 – 1.5

750

Sand/ Gravel 1800 1800--2000

0.8 – 1.2

500

Sandy/clay /clayey

1600--2000 1600

0.8 – 1.2

600

Clay

2000 2000--2500

0.8 – 1.0

400

Asphalt

25002500-3500

0.4 – 0.6

50 – 75 44

Effect Of Speed Of Roller In Density And Finish Surface

ROUGH SMOOTH

FINISH

FINISH

HIGHER SPEED LOW DENSITY

LOWER SPEED HIGH DENSITY

OPERATION SPEED

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Relationship Between Compactability & Temperature

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TACK COATING BY SPRAYER

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Tack Coat Without Crack Sealing

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Overlay Over Severely Cracked Surface

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Inadequate Compaction And Excess Binding Material

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WBM Surface Without Key Aggregates And Excess Binding Material

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Shoulders At Higher Elevation

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Poorly Widened WBM Carriageway

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POORLY WIDENED WBM CARRIAGEWAY

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Depressed Carriageway

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Tack Coat Surfaced WBM Layer

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Modern Equipment For Quality Control Tests In Highways Construction

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Asphalt Content Guage

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Portable Pendulum Type Skid Resistance Tester

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Dynamic Skid Resistance Tester

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Portable Asphalt Core Cutter

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Non Nuclear Density Gauge

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Benkelmen Beam

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Fifth Wheel Bump Integrator (Roughometer)

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Nuclear Density Meter

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Asphalt Content Guage

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Falling Weight Deflectometer

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