Durability Plans

Introduction

Whilst Australian codes gives some guidance on design for durability they are severely limited, conflicting and in some case provide inadequate guidance. BCRC have the extensive background necessary to competently consultant on building and construction materials durability issue, i.e.:

• BCRC models have been developed for assessing durability design in a wide range of circumstances
• BCRC are at the leading edge of research
• BCRC maintain expertise by attendance at international conferences
• BCRC have extensive experience as durability consultants on some of Australia’s largest and most exposed projects
• BCRC maintain active membership of international  durability committees
• BCRC maintain international associates who are leaders in their respective durability fields
• BCRC have compiled a huge electronically referenced library on concrete durability

Durability design must also take account of design and construction criteria. BCRC designs are cognisant of:

• Structural implication (cover, strength development, detailing)
• Construction requirements (short finishing times, early stripping, simple placing and curing, minimise activities, eliminate repairs)
• Supply issues (performance specifications, mix trials, site testing, lab testing)

 

SELECTED OTHER PROJECTS
Infrastructure	Marine	Water	Industrial/Mines
Wellington St Station Diaphragm walls subject to a 15m pressure of water with chlorides and sulphates.	Perth Desalination Plant For all materials considered saline water, immersed structures, de-mineralised water, salt spray.	Melbourne’s NSP 2 Sewers External saline ground water in Silurian (PASS). Internal exposure: sulphide, H2S and sulphuric acid build up.	FMG Coal Unloader Thermal and durability analysis in coastal area with high in ground salts
Canning River Bridge Limited to the pile assessment through Potentially Acid Sulphate Soils.	Gold Coast  Desalination Plant All concrete works. Similar to Perth Desalination Plant.	Kalgoorlie Reservoir Considered reinforcement and joint details for crack control of massive slab area.	Power Station Singapore Assessment of ground condition to UK standards.
Orrong Rd Interchange Full Durability Plan. Provision for thick sections in winter and summer casting.	Port Botany Advice to Tenders on Durability Plan Requirements	Australind Water Tank Coastal Durability Plan. Also prepared concrete mix requirements.	Power Station Fremantle Specification of Coastal durability requirements
Mitchell Freway Durability Consultants for bridges and tunnels	LNG Jetty Advised contractor on design for life	John Hill Reservoir Water tanks and related infrastructure.	Boddington Mine Thermal Analysis of mass foundations

Expertise Required

Major projects can incorporate many different durability mechanisms that require the experience from durability experts in various disciplines. BCRC has specialist that cover all aspects of concrete and steel deterioration and so are uniquely able to offer a complete durability consultancy service for major infrastructure projects. BCRC’s consultants around the worlds ensure the latest international information is incorporated in each plan.

Durability Plan Stages

The DP is generally developed in four stages

• An Outline Durability Plan (ODP) developed to support that the tender design sets out the approach to the Durability Planning specific to the project and the qualifications and experience of the Durability Team so that the client can judge the adequacy of what is offered.
• Depending on the size of the project, the full Durability Plan (DP) is generally developed over the 2 months after award of contract. It is undertaken in conjunction with the Design and Construction team to ensure that the DP provisions compliment the proposed design and construction methods.
• The structure specific durability requirements need considerations as design changes and details evolve through the detailed design process. As the design is finalized a durability section of the design report, or a Durability Design Report (DDR), for each structure details how the requirements of the DP are incorporated in the deign and notes any changes to DP requirements due to additional exposure information or design changes. A major upgrade to DP requirements at this stage is maintenance planning.
• The Construction Team are required to ensure the Durability Design Report requirements re incorporated into the structure. This entails construction to the design and checking that construction is to the design. This is verified by the Durability Consultant checking that:
  • the Method Statements will provide enable the required quality will be achieved
  • the Quality Plan and non – conformance register to ensure that the appropriate testing is undertaken and non-conformances are appropriately closed out.
• On completion of construction of each structure the Construction Team are required to provide a Durability Assessment Report (DAR)  that details how the construction has ensured the requirements of the Durability Plan.

 

Development Of The Durability Plan

The following outlines, in a sequence of steps through the design and construction phases, the process that is used to develop a DP and to achieve the objectives of the DP.

1. Breakdown the Project Works into different environmental exposure categories. Where appropriate these categories correspond to categories in AS3600, AS3735, AS2159 or AS2312. Where necessary for making realistic design assessments site measurements are instigated.

2.   The durability of each element type in each environment is assessed by considering all deterioration mechanisms.

3. Thermal and crack width analysis are undertaken to ensure reinforcement design is compatible with construction methods and material.

4. The risk (consequence and likelihood) of durability failure, the materials inspection and testing requirements and monitoring requirements are welded into a Durability Plan

5. Prescriptive and performance based materials and workmanship requirements for each Element type in each exposure zone are prepared.

Incorporation Into The Design

7. The Design Manager ensures that the requirements of the Durability Plan are incorporated into the design by appropriate inclusions in the calculations, assessments, specifications and drawings.

8. The Durability Consultant in conjunction with the Design Team ensure that the DDR of each design lot includes

• Tabulation of final performance and prescriptive requirements for each element
• How the DP requirements have been achieved
• Summary of exposure conditions
• Survey of facilities in regards CP
• Requirements for assurance of structural integrity

9. Materials & construction specifications for construction are prepared by the Durability Consultant in conjunction with the Design Team (e.g. concrete supply; concrete placing, finishing and curing; prestress grouting; shotcreting; coating;  weld inspection, equipment durability performance; joints; waterproofing; inserts)

Incorporation Into Construction

10.  The Construction Manager ensures that the requirements of the Design Documentation are met by development of appropriate method statements. As a minimum the following processes would require preparation of method statements, where required:

• Insitu concrete temperature control
• Steam cured concrete temperature control
• Plastic crack & plastic settlement crack control
• Placing, compacting, finishing & curing
• Construction of specific elements types
• Cutting concrete
• Construction joints
• Installing fixing
• Breaking out and reinstating concrete
• Grouting of prestressing ducts
• Stress bar installation
• Concrete production
• Pre-construction trial mixes
• Minor defect repair
• Steel work inspection

11.  The Construction Manager ensures that the required method statements are reviewed by the Durability Consultant.

12.  The Construction Manager ensures that the requirements of Method Statements are implemented in the relevant construction of Project Works.

Verification of each elements durability

13.  Testing and quality records of the construction are established as the work proceeds. The Durability Consultant reviews sufficient to ensure compliance.

14.  The verification process requires that a non-conformance be registered wherever materials or workmanship are identified as defective. The Durability Consultant review the remedial solution wherever durability is involved.

Maintenance Requirements

15.  The Durability Consultant and Design Team work together to prepare a Maintenance Schedule.

Conclusion

Ensuring durability of major infrastructure projects is vital. Lack of durability can lead to unacceptable failures and high maintenance costs. BCRC are uniquely able to provide local and international expertise to prepare durability plans for all major infrastructure projects.