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Standing Committee on Concrete Technology Annual Concrete Seminar 2007

High Workability Concrete for Bored Pile Construction

CC Wai, Alan Wan Gammon Construction Limited

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Week 2

Week 3

Week 1

Sequence of Work in Bored Pile Construction

Sun Mon Tue Wed Thu Fri Sat

Excavation

Excavation Rock Drilling

Rock Drilling Airlifting Concrete Cage

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Presentation Scope

Method of Concreting Bored Pile

Problems and Defects

Deficiencies in Current Practice

Proactive Approach

The Way Forward

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Concreting of Bored Pile

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General Setup

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Ramp

Skip

Tremie Pipe

Concreting Platform

Concrete Truck

Concrete

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Stages in Bored Pile Concreting

(1) (2) (3) (4)

Extract Tremie Pipe Extract Temporary Casing

Concrete Overbreak

Drop in Concrete

Head

Tremie Pipe

Temporary Casing

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Cement Grout

Concrete

QA / QC

Slump tests / Flow table

Check temperature ( 32o)

Cube samples to determine concrete strength

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Concreting Takes Many Hours

12:00 14:00

18:00 21:00

30

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Pile Length (m)

Concreting Time Varies With Pile Length

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Slump Varies With Time

Time

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Common Problems Encountered

Temporary casing cannot be withdrawn

Tremie pipe cannot be withdrawn

Blocked tremie pipe

Reinforcement cage rides up with temporary casing

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Defects

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Honeycomb

Reduced workability affects self compaction

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Air Voids

Entrapped Air Inside Concrete During Pouring

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Air Voids

(1) (2) (3) 18

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Segregated Concrete

Additive quantity needs fine-tuning

Remedial Actions

Grouting

High pressure water jet to remove weak concrete, followed by pressure grouting

Stitched pile

Additional pile

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Deficiencies in Current Practice

First In . Last Out

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1 *

2

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First few truckloads need to remain workable throughout concreting

* Indicate order of truckload

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Deficiencies in Current Practice

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Large piles / deep piles mean large concrete volume

Specification / Contract Document Single slump value specified on drawing Workability vs time not considered Lack of flexibility in interpretation

Quality control Need to control consistency in material

properties

23

The Proactive Approach

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Need to Consider .. Specification Concrete volume (related to pile size

and depth) Site constraints (physical or

environmental restrictions) Site location (travel time to site from

batching plant) 24

Pile Acceptance

Time

Concrete Performance

Material Consistency

Concrete Site Construction Volume Constraints Procedure

Route to Pile Acceptance

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25

Delivery ~ 3 hours

Grade 45/20 Designed slump 200mm

Workability 5 hours

SUCCESS STORY

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Hong Kong Shenzhen Western Corridor

26

SUCCESS STORY Hong Kong Shenzhen Western Corridor

2

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Supplier formulated a special concrete mix with enhanced workability

Engineer relaxed concreting time to 5 hours

Contractor checked workability prior to pouring

Side-effect : minor segregation, need to pour additional concrete to avoid undercasting

27

2

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28

Way Forward

Concrete Triangle

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Designer

Contractor Concrete Supplier

Concrete Quality / Performance

Constructability

Slump Retention Consistency

29

2

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30

The End

Structure Bookmarks2005 Gammon Construction Limited. All Rights Reserved Standing Committee on Concrete Technology. Annual Concrete Seminar 2007. High Workability Concrete for. Bored Pile Construction. High Workability Concrete for. Bored Pile Construction. CC Wai, Alan Wan. Gammon Construction Limited. 2006 Gammon Construction Limited. All 2 Sequence of Work in Bored Pile Construction. Sequence of Work in Bored Pile Construction. Sun Sun Sun Mon Tue Wed Thu Fri Sat

Week 1 Week 2 Excavation Excavation Excavation Rock Drilling Week 3 Rock Drilling Rock Drilling Rock Drilling Airlifting

Concrete Cage 2006 Gammon Construction Limited. All Rights Reserved. 2006 Gammon Construction Limited. All Rights Reserved. 4

Presentation Scope. Presentation Scope. Method of Concreting Bored Pile.

Problems and Defects

Deficiencies in Current Practice.

Proactive Approach

The Way Forward

2006 Gammon Construction Limited. All Rights Reserved. 2006 Gammon Construction Limited. All Rights Reserved. 6 Concreting of Bored Pile

General Setup. General Setup. 2006 Gammon Construction Limited. All Rights Reserved. Ramp Skip Tremie Pipe Concreting Platform Concrete Truck Concrete

Stages in Bored Pile Concreting. Stages in Bored Pile Concreting. (1) (2) (3) (4) Extract Tremie Pipe Extract Temporary Casing Concrete Overbreak Drop in Concrete Head Tremie Pipe Temporary Casing 2006 Gam 2006 Gammon Construction Limited. All Rights Reserved. 9 Cement Grout Concrete

QA /QC. QA /QC. . . . Slump tests / Flow table

. . Check temperature ( 32) o

. . Cube samples to determine concrete strength

2006 Gammon Construction Limited. All Rights Reserved. 2006 Gammon Construction Limited. All Rights Reserved. 11 Concreting Takes Many Hours 12:00 14:00 18:00 21:00 Concreting Time Varies With Pile Length. 2006 Gammon Construction Limited. All Rights Reserved. Time (hours) 30. 25. 20. 15. 10. 5. 0. Figure0 20 40 60 80 100. Pile Length (m). 0 20 40 60 80 100. Pile Length (m).

2006 Gammon Construction Limited. All Rights Reserved. 13 Slump Varies With Time Time Slump

Common Problems Encountered. Common Problems Encountered. Temporary casing cannot be withdrawn.

Tremie pipe cannot be withdrawn

Blocked tremie pipe

Reinforcement cage rides up with temporary casing

2006 Gammon Construction Limited. All Rights Reserved. 2006 Gammon Construction Limited. All Rights Reserved. 15 Defects 2006 Gammon Construction Limited. All Rights Reserved. 16 Honeycomb Reduced workability affects self compaction 2006 Gammon Construction Limited. All Rights Reserved. 17 Air Voids

Entrapped Air Inside Concrete During Pouring. Entrapped Air Inside Concrete During Pouring. 2006 Gammon Construction Limited. All Rights Reserved. Air Voids (1) (2) (3) 2006 Gammon Construction Limited. All Rights Reserved. 19 Segregated Concrete Additive quantity needs fine-tuning

Remedial Actions. Remedial Actions. Grouting

High pressure water jet to remove weak. concrete, followed by pressure grouting.

Stitched pile

Additional pile

2006 Gammon Construction Limited. All Rights Reserved. 2006 Gammon Construction Limited. All Rights Reserved. 21 Deficiencies in Current Practice

First In . Last Out. First In . Last Out. 2006 Gammon Construction Limited. All Rights Reserved. First few truckloads need to remain workable throughout concreting 16 17 1 * 2 3 18

* Indicate order of truckload

Deficiencies in Current Practice. Deficiencies in Current Practice. 2006 Gammon Construction Limited. All Rights Reserved. . . . Large piles / deep piles mean large concrete volume

. . . Specification / Contract Document

. . . Single slump value specified on drawing

. . Workability vs time not considered

. . Lack of flexibility in interpretation

. . Quality control

Need to control consistency in material properties

The Proactive Approach. The Proactive Approach. 2006 Gammon Construction Limited. All Rights Reserved. Need to Consider .. Specification

Concrete volume (related to pile size and depth)

Site constraints (physical or. environmental restrictions).

Site location (travel time to site from batching plant)

Route to Pile Acceptance. Route to Pile Acceptance. Pile Acceptance Time Concrete Performance Material Consistency 2006 Gammon Construction Limited. All Rights Reserved. Concrete Site Construction. Volume Constraints Procedure.

SUCCESS STORY. SUCCESS STORY. 2006 Gammon Construction Limited. All Rights Reserved.

Hong Kong Shenzhen Western Corridor. Hong Kong Shenzhen Western Corridor. Delivery ~ 3 hours Delivery ~ 3 hours Figure

Grade 45/20

Designed slump 200mm

Workability 5 hours

Figure

SUCCESS STORY. Hong Kong Shenzhen Western Corridor. SUCCESS STORY. Hong Kong Shenzhen Western Corridor. 2006 Gammon Construction Limited. All Rights Reserved. Supplier formulated a special concrete mix with enhanced workability

Engineer relaxed concreting time to 5 hours.

Contractor checked workability prior to pouring

Side-effect : minor segregation, need to pour additional concrete to avoid undercasting

2006 Gammon Construction Limited. All Rights Reserved. 28 Way Forward Concrete Triangle. 2006 Gammon Construction Limited. All Rights Reserved. Designer Contractor Concrete Supplier Concrete Quality / Performance Constructability Slump Retention Consistency 2006 Gammon Construction Limited. All Rights Reserved. 30 The End