Quality Management of Precast Concrete Segments for Wind Turbine Towers

Quality Management of Precast Concrete Tower Segments for Wind Turbine Towers

CONCRETE GROWTHconcrete materials engineers

Santie Gouws Quality Manager – Precast Concrete Tower Segments for Acciona Windpower;MD - Concrete Growth


Wind Energy (I)

Rotor

Hub

Tower

> 80 m

Rotor

Blades

Nacelle

Enclosing

African

Elephant

http://en.wikipedia.org/wiki/File:African_Bush_Elephant.jpg

http://en.wikipedia.org/wiki/File:African_Bush_Elephant.jpg


Wind Energy (II)

Development of Turbine Capacity and

Tower Height

Hybrid

towers


Wind Energy (III)

Tubular steel towers

Concrete towersTower technology options

• SA economic development depends on

• Electricity supply

• Job creation

• IRP 2010 to 2030

• 55 000 MW to be installed in next 20 years

• Up to 9 200 MW wind energy through REIPPP

• 2,5 to 3MW turbines - > 3000 tower structures

• Tower structure ~ 15 % of capital cost of wind farm

• Round 3 Local content requirements:

→ increased to threshold of 40%, target of 65%

• Concrete towers, relatively new technology internationally,

but obvious contender for local contentCONCRETE GROWTHconcrete materials engineers

Wind Energy in South Africa (I)


Wind Energy in South Africa (II)

Development of Turbine Capacity and

Tower Height


Wind Energy in South Africa (III)

Cost of Energy vs Hub Height

CSIR,

Greene &

E-Science

Associates


Wind Energy in South Africa (IV)

Job creation – impact of 50MW wind farm

446

525

525

346

368

368

250

266

266

836

1 380

1 746

691

1 080

1 441

679

902

1 267

1 052

1 350

1 630

796

997

1 272

669

784

1 063

- 1 000 2 000 3 000 4 000

120m Imported steel tower

120m Concrete tower


100m Concrete tower


80m Concrete tower

Number of Full Time Equivalent jobs

Direct impactIndirect impact

Induced impact

CSIR, Greene &

Urban-Econ

Development

Economists CONCRETE GROWTHconcrete materials engineers


Acciona Windpower (I)

International Footprint

Canada 45 MW

USA 704 MW

Mexico 555 MW

France 39 MW

Spain 1,607 MW

UK 32 MW Poland 120 MW

Greece 6 MW

Italy 68 MW

South Korea 68 MW

Australia 239 MW

Chile 60 MW

China 249 MW


Acciona Windpower (II)

South Africa

Canada 120 MW

USA 6 MW

Mexico 258 MW

Spain 99 MW

Poland 33 MW

Brasil 330 MW

Chile 45 MW South Africa 148 MW

AW 3000 Orders and Commitments (2013)


Acciona Windpower (III)

Current 3.0 MW WTG dimensions

• Blades:

• Length: 48m-61.5m

• Weight: 10t-12t

• Nacelle + Hub:

• Length: 17.6m

• Weight: 140t

• Tower

• Length: 87.5m-95.5m (Steel); 100m-120m (Concrete)

• Weight: 290t (95.5m Steel); 1180t (120m Concrete)

Acciona Windpower (IV)

Acciona Windpower (V)

Acciona Windpower (VI)


AWP Wind Farm in Spain

DESIGNED FOR RE-PRODUCTIONSTRONG QUALITY CONTROL SYSTEM

GOUDA WIND FARM

• 46 x 3 MW WTG’s

• 100 m high concrete tower support

structures

• Assembled from 5 by 20m cylindrical

pre-assembled units

• Final assembly onto in situ foundation

and post-tensioned

• 17 individual segments/tower

Reproduction of AWP towers as

done elsewhere in the worldCONCRETE GROWTHconcrete materials engineers

Acciona Windpower (VII)

GOUDA WIND FARM

• Individual concrete segments manufactured by

Concrete Units in Cape Town for the 1st time,

transported to Gouda

• 782 segments cast from 5 re-usable moulds

• Each segment weighs

60 tonnes

• 9 months of

precasting

Strong AWP Quality

Control SystemCONCRETE GROWTHconcrete materials engineers

Acciona Windpower (IIX)

• Semi-circular, tapered concrete element

• Building-blocks of concrete towers


Keystones - building blocks (I)

20m

• Keystones at Concrete Units Factory in CT


Keystones – building blocks (II)

• Top & Bottom of Keystones, horizontal joints


Keystones – building blocks (III)


Keystones - building blocks (IV)• Vertical joints of keystones

• Keystones being

pre-assembled

at Gouda


Keystones – building blocks (V)

• Level 1

immediately

installed

onto foundation

• Levels 2 to 4

pre-assembled onto

trestles

• Vertical joints

grouted before

final assembly


Keystones – building blocks (VI)

• Levels 1, 2 & 3 – 4 keystones each

• Level 4 – 3 keystones

• Level 5 – 2 keystones


Keystones – building blocks (VII)

• Concrete Batching• Batching plant & ready-mixed concrete trucks

• Mould Set-up• 5 moulds for 782 keystones, re-used daily

• Keystones are cast horizontally

• Mould has bottom section and lid

• Reinforcement and Fixtures• 1 reinforcement design for keystones of each level

• Fixtures differ per keystone per level, depending on

position in tower

• Concrete Casting• Self-compacting concrete pumped into moulds

• Curing and Demoulding• Thermal curing up to required strength

• Demould 1 day after casting

• Final Finishing• On temporary support structure - horizontallyCONCRETE GROWTH

concrete materials engineers

Keystone Manufacture (I)


Keystone Manufacture (II)Concrete Batching Process

Mould Bottom with Cover Blocks


Keystone Manufacture (III)

Reinforcement and Fixtures


Keystone Manufacture (IV)

Reinforcement and Fixtures


Keystone Manufacture (V)

Mould Lid being Placed


Keystone Manufacture (VI)

Mould with lid on


Keystone Manufacture (VII)

Concrete Casting


Keystone Manufacture (IIX)

Demoulding


Keystone Manufacture (IX)

Final Finishing


Keystone Manufacture (X)

Top after Final Finishing


Keystone Manufacture (XI)

TO ENSURE ‘QUALITY’:

WHICH ASPECTS DO WE WANT TO

CONTROL AND WHY?

• Structural Design Requirements

• Production Requirements

• Functional Requirements for Tower

Assembly and use in Tower


Aspects to Control (I)

Structural Design


Aspects to Control (II)

DIMENSIONS

INPUT REQUIRED OUTPUT

MOULD DIMENSIONS GEOMETRY of KEYSTONES

MOULD DESIGN TOWER GEOMETRY

CONCRETE MATERIAL PROPERTIES


RAW MATERIALS COMPRESSIVE STRENGTH

PROPORTIONS of RAW MATERIALS

COMPACTION

TIME of MIXING

TEMPERATURE

Structural Design


Aspects to Control (III)

REINFORCEMENT & POST TENSIONING


RAW MATERIALS LOAD BEARING CAPACITY

SHAPE AND SIZE - KEYSTONES during PRODUCTION PROCESSES

POSITION - FINAL TOWER

COVER TO REINFORCEMENT


COVER DEPTH DURABILITY

LIMITS ON CRACKS

Structural Design


Aspects to Control (IV)

JOINTS BETWEEN KEYSTONES


GEOMETRY OF VERTICAL JOINTS

VERTICAL STRUCTURAL CONNECTION

VERTICAL JOINT REBAR

GEOMETRY OF TOP & BOTTOM OF KEYSTONE

HORIZONTAL STRUCTURAL CONNECTION

REBAR POSITION

REBAR LENGTH

REBAR STRAIGHTNESS

DUCT DIMENSIONS & LENGTH

Functional Requirements


Aspects to Control (V)

PRE-ASSEMBLY FIXTURES


ANCHOR BOLT CONNECTION INSERTS PROPERTIES AND POSITIONS

KEYSTONE POSITIONING during PRE-ASSEMBLY

DUCT DIMENSIONS KEYSTONE POSITION AND LEVEL IN TOWER for TOWER GEOMETRY

BOLT CONNECTION INSERTS PROPERTIES AND POSITIONS

WORKING PLATFORMS

PRE-ASSEMBLY


Levelling tool

Prop support

fixture

Vertical joint

Aspects to Control (VI)

Platform



Aspects to Control (VII)

LIFTING MECHANISMS


TPA POSITION & PROPERTIES LIFT HORIZONTALLY

LIFTING LOOP DIMENSIONS & POSITIONING

LIFT VERTICALLY

FIXTURES FOR OPERATION OF TOWER


BOLT CONNECTION INSERTS PROPERTIES & POSITIONS

ELECTRICAL CABLING

MECHANICAL LIFT


• TPA’s for lifting in horizontal position


Aspects to Control (IIX)


• Lifting loops

• Ducts


Aspects to Control (IX)

Manufacturing Requirements


Aspects to Control (X)

MOULDS


FLOWABILITY OF CONCRETE MOULD DESIGN FOR HORIZONTAL CASTING

DEMOULDING STRENGTH MOULD TURN-AROUND TIME

THERMAL CURING

SUPPORTS AFTER DEMOULDING


DEMOULDING STRENGTH BE ABLE TO BE SUPPORTED ON TWO POINTS ONLY AFTER DEMOULDING


Quality System Overview (I)• Engineering Specification & Design

• Functional Design and Structural Design by AWP Engineering

• Based on International Structural Design Code – Eurocode

• Captured in Engineering Drawings and Project Specifications

• Comparison with SANS and Adaption of Specification where Relevant

• Instructions• Documents describing how each action shall be performed in order to meet

the Engineering Design and Specifications

• Inspection Sheets• Documents filled in throughout each step of the process documenting the

procedures followed

• Quality Teams• Contractor – Responsible for Manufacturing according to the quality

specifications; and for documenting their procedures according to the

Quality System

• AWP Quality Team – Inspection of actual processes and checking of

documentation to ensure processes were correctly followed; coordination

with AWP Engineering team where specifications not clear or where

deviations are required for practical, local reasons


Quality System Overview (II)• Traceability

• From Raw Material to Keystone throughout all Processes

• Tolerances• +/-

• There are no ABSOLUTES

• In line with Engineering Design & Functional Requirements

• Practically Achievable at Related Cost

• Frequency of Measurement• Initial Production

• Serial Production

• Differs per material type depending on inherent variability & application

Entire process is broken down into individual steps and each is

checked and documented against fixed, repetitive, easy-to-

check criteria

engineering specifications/drawings


Quality System Overview (III)

engineering support

INSTRUCTIONS

INSPECTION

SHEETS

QUALITY

TEAM


Quality System Overview (IV)SPECIFY MEASURE

&

RECORD

DESIGN

CORRECT

CANNOT

CORRECT

ok

production

deviation

specification

deviation

not ok

Design Code


Quality System

Project Specifications


Quality System

Engineering Drawings - Concrete


Quality System

Instructions - Concrete


Quality System

Inspection Sheets - Concrete


Quality System


• FLOW TEST FOR

SE SELF-COMPACTING

C CONCRETE

R RECORDED ON SHEET


Quality System


• Cube specimens


Quality System


• Strength testing


Quality System



Quality System

Supporting Documentation - Concrete


Quality System

Engineering Drawings - Reinforcement


Quality System

Instructions - Reinforcement


Quality System

Control Sheets - Reinforcement


Quality System


Case Study – Lost in translation (I)


Case Study – Lost in translation (II)


Case Study – Lost in translation (III)


Case Study – Ducts too small (I)


Case Study – Ducts too small (II)


Case Study – Ducts too small (III)

Measure already cast-in ducts to

determine extent of problem


Case Study – Ducts too small (IV)

Measure new batches


Case Study – Ducts too small (V)


Case Study – Ducts too small (VI)Update Specification & Inspection Sheets


Case Study – Too much water (I)Batch Plant


Case Study – Too much water (II)Batch plant control


Case Study – Too much water (III)Batch record


Case Study – Too much water (IV)Confirmed by Concrete Test Result

www.acciona.com

www.concretegrowth.com

www.concreteunits.co.za

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Quality Management of Precast Concrete Segments for Wind Turbine Towers

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