East Anglia Construction Safety Group21 April 2011

Temporary Works

What’s Changed

Eur. Ing. Peter Pallett

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ContentContent

1. Introduction1. Introduction

2. Changes 2009 - 2011(a) Procedures(b) Falsework(c) Scaffolding

2. Changes 2009 - 2011(a) Procedures(b) Falsework(c) Scaffolding

3. Changes in 2011(a) Wind(b) Formwork

3. Changes in 2011(a) Wind(b) Formwork

Part One - IntroductionPart One - Introduction

“Temporary Works”“Temporary Works”Definition:

Works undertaken during construction but not required to form part of the finally completed construction works.

Includes the works to stabilise or protect an existing building or structure that are not intended to be permanent.

Cofferdams

Tower Crane Bases

Support to Cabins over River Thames

Temporary Façade Retention Structures

RMD-Kwikform

Scaffolding

Harsco Infrastructure

Upper Forth Crossing - 2008 27,000 ton 1.2 km

Steel wall formwork - Housing

Hindhead Tunnel A3 November 2009

1 of 2 Leada-Acrow

Soffit Formwork and Falsework

Typical costs for a reinforced concrete frame

Item material labour % ofcost & plant total

Concrete 15 % 8 % 23 %

Reinforcement 14 % 6 % 20 %

Formwork andfalsework 9 % 30 % 39 %

Sundries etc 12 % 6 % 18 %

Totals 50 % 50 % 100%

Source: Formwork - a guide to good practice

Part Two - Changes 2009 - 2011

(a) Reminder of The Law

and

TW Procedures

Part Two - Changes 2009 - 2011

(a) Reminder of The Law

and

TW Procedures

CDM 2007

Approved Code of Practice and theCDM Regs 2007

Document L144March 2007124 pages

£15Source: http://books.hse.gov.uk

Tel: 01787 881 1651 of 4

Construction (Design and Management) Regs 2007 Approved Code of Practice (ACOP)

104 : The design of temporary works, such as falsework, formwork and scaffolding, falls within the scope of the CDM 2007 Regs..

CDM co-ordinators have to take reasonable stepsto ensure co-operation between permanent and temporary works designers, in particular to ensure that arrangements are in place to ensurethat designs are compatible and that the permanent works can support any loadings fromtemporary works.

2 of 4

CDM Regs 2007Industry Guidance

for Designers

Published May 2007(50 pages)

(Available as free *.pdf from Construction Skills )3 of 4

Guidance for Designers (CDM07/4)

2.6.8 Designers need to consider how the structurecan be constructed, cleaned, maintained anddecommissioned. This may involve:

checking that the overall design takesfull account of any temporary works needed,

no matter who is to develop those works.

checking that consideration has been given to the availability of sufficient space

and adequate ground support for large plant required to construct or maintain the structure.

4 of 4

BS 5975 : 2008

Code of practice fortemporary works

procedures and

the permissible stress design of falsework

Chairman: Frank Marples

Permissible Stress

1 of 10

First published 1982

£270Draft fo

r Public Comment

BS 5975:2008+A1:2011

Section 2 Procedures and 17.5.1 Wind

Typical Register used as Active Site Document

2 of 10

Appointment of Temporary Works Co-ordinator

7.3.1 The appointment of a temporary works co-ordinator (TWC) should be the first operationin a chain of events culminating in the construction of a Temporary Works scheme.

3 of 10

NOTE: In large organisations the TWC may be proposed by a Contracts Director / manager or similar but the designated individual should be satisfied that the proposed TWC has the abilities outlined in 7.1.2 before confirming acceptance of the proposal.

The TWC should be appointed by the designated individual of the main or principal contractor.

Source BS 5975:2008+A1:2011

7.1.2 It is essential for the TWC to be competentand have relevant up-to-date training and bothqualifications and the experience appropriate to the complexity of the project.

BS 5975:2008 Clause 7.2.5Activities of the Temporary Works Coordinator

c) ensure that a design brief is prepared with full consultation, is adequate, and is in accord with the actual situation on site;

d) ensure that any residual risks, (assumed constructionmethods or loading constraints) are included;

e) ensure a satisfactory temporary works design is carried out;

f) ensure that a design check is carried out by someone not involved in original design - for concept, structural adequacy and brief compliance;

n) after a final check, which is satisfactory, ensure a permit toload is issued by either the TWC or TWS;

o) when it has been confirmed that the permanent structurehas attained adequate strength, ensure a permit to dismantle is issued by either the TWC or TWS;

4 of 10 ( Source BS 5975:2008+A1:2011 )

Typical letter of appointment

of a TWC

On larger sites the appointment of a Temporary Works Supervisor is also

recommended

5 of 10

Appointment of Temporary Works Supervisor

7.3.1 On larger sites or where site manager or project manager considers it necessary, orwhere there are one or more subcontractors carrying out temporary works operations, orwhere the TWC requests assistance, one or more TWS’s may be appointed.

The TWS should be appointed by the designated individual of the organisation for whose work the TWS is responsible.

Source BS 5975:2008+A1:20116 of 10

Appointment of Temporary Works Supervisor

6.4.5 Contractors carrying out a number of small contracts may appoint a TWC with overallresponsibility and a TWS, with an appropriate level of authority for each individual site.

7.3.2 It is essential for the TWSs to be competentand to have relevant up-to-date training andboth qualifications and the experienceappropriate to the operations for which theyare responsible.

Source BS 5975:2008+A1:20117 of 10

BS 5975:2008 Design Check Categories

Category Scope Independence

2More complex design. by individual not excavations, structural involved in design steelwork, foundations, and not consulted bytop restrained etc. the TW designer

3 Complex or by another innovative design organisation

1Simple design

( falsework top restraint is NOT assumed )

by another member of design team

Restricted to standard solutionsO

Site issue - by another member of site teamor design team

8 of 10

Typical Permit

toLoad

9 of 10

10 of 10

Part Two - Changes 2009 – 2011

(b) Falsework

Part Two - Changes 2009 – 2011

(b) Falsework

Any temporary structure used to support a permanent structure while

it is not self-supporting.

RMD-Kwikform

Support of Twin wall and Precast soffit

BS EN 12812: 2008

Falsework

PublishedJanuary 2011

Limit State Design

£170Chairman: Frank Marples

1 of 4

BS EN 12812: 2008 Design classes for falsework

Dimensional limitations and generally restricts application to building work.

Structural performance is derived from pre-existing knowledge of the performance of the components of the structure, such as props etc..

Class A

Such information is often included in standard solutions.

Source NA.4

Class B Falsework where a complete design is undertaken. There are two sub-classes.

2 of 4

Design classes for falsework

Class A Class B1 Class B2

3 of 4

Simplified design in BS EN 12812

and/or in accordance with

relevant EuroCodes

Slab area < 0.3 m²(ie 300mm)

Beams < 0.5 m²

Clear span < 6.0 m

Height < 3.5 m (measured to underside

of permanent works)

Design in accordance

with relevant EuroCodes

Most falsework in this class

But there is a γm x 1.15

BS 5975 : 2008

Code of practice fortemporary works

procedures and the permissible stress

design of falsework

First published 1982

Permissible Stress

£270

Chairman: Frank Marples4 of 4

BS 5975:2008New Loadingson Falsework

BS 5975:2008New Loadingson Falsework

Construction Operations - Working Area Load

Allow for a Service Class 1 load of only 0.75 kN/m²over the entire area, including access and working areas.

i.e. only 30mm extra concrete !

BS 5975 - The British Standard Heap - Cl 17.4.3.1 1 of 3

Working Area Load

Working areaService Class 1load 0.75 kN/m²

BS 5975 Clause 17.4.3.1 2 of 3

Additional Transient In-situ Concrete Load

Working areaService Class 1load 0.75 kN/m²

In-situ concrete loading 0.75 kN/m² to 1.75 kN/m² 3m 3mTotal load equal

to 10% concrete load

2 of 3BS 5975 Clause 17.4.3.1

In-situ Concrete Construction Operations LoadsSummary

Thickness calcs Total

Up to 300mm 0.75 + 0.75 1.50 kN/m2

Over 700mm 0.75 + 1.75 2.50 kN/m2

300 to 700mm 0.75 + 10% t 0.75 + 10% of weight of concrete

Slab thickness t

3 of 3

1 of 1

Permanent formworkminimum

constructionload of 1.50 kN/m2

Working Areas - Access for striking

Wherever falsework requires removal of individual pieces, for example striking primary or secondary

bearers, consideration should be given to a working platform about two metres below the underside of

the permanent works.

Where the formwork and falsework is handled in large areas, provision for access to make-up areas

should be considered.

( Use Service Class 1 load - 0.75 kN/m2 )

1 of 2 BS 5975 Clause 19.1.1

Consider access underneath for striking

Tall frame structure2 of 2

BS 5975:2008The Four Design

Checks for Falsework

BS 5975:2008The Four Design

Checks for Falsework

Falsework AnalysisIt is recommended that for each falsework structure FOUR design checks be carried out:

Check ONE - on the STRUCTURAL STRENGTH of the individual members and their connections to transmit the applied loads / forces;

Check TWO - on the LATERAL STABILITY of both individual members and the structure as a whole;

Check THREE - on the OVERALL STABILITY of the falsework structure;

Check FOUR - on POSITIONAL STABILITY to ensure the falsework does not slide.

Source: BS 5975 Clause 19.4.1.1

THINK VERTICAL

THINK HORIZONTALand then,

THINK HORIZONTAL AGAINand again,

and again,

and again.

BS 5975:2008

Check One

Structural Strength

BS 5975:2008

Check One

Structural Strength

BS EN 1065

Adjustable telescopic steel props

Published November 1999

Committee: CEN

£150.00

1 of 6

Class Max. Extension Characteristic strength

A 25 2.50 m 20.40 kN A 30 3.00 m 17.00 kNA 35 3.50 m 14.60 kN A 40 4.00 m 12.80 kNB 25 2.50 m 27.20 kNB 30 3.00 m 22.70 kN B 35 3.50 m 19.40 kN B 40 4.00 m 17.00 kNB 45 4.50 m 15.10 kNB 50 5.00 m 13.60 kNB 55 5.50 m 12.40 kNC 25 2.50 m 40.80 kNC 30 3.00 m 34.00 kNC 35 3.50 m 29.10 kNC 40 4.00 m 25.50 kNC 45 4.50 m 22.70 kNC 50 5.00 m 20.40 kNC 55 5.50 m 18.60 kN

D 25 to D55 2.50m to 5.50m 34.00 kNE 25 to E55 2.50m to 5.50m 51.00 kN

BS EN 1065

Props to have minimum of

1.0m adjustment, and not to be

intentionally dis-engaged

2 of 6

Characteristic strength is the value at which 95% of those tested will fail above value

(ie 5% will fail below value)

Characteristic strength is the value at which 95% of those tested will fail above value

(ie 5% will fail below value)

3 of 6

Stellenbosch - South Africa - 2009

Removed TWO internal walls

200mm thick x 14m slab4 of 6

Supplier claim 29.80kN characteristic load

Thin walled props3.2m (too short)5 of 6

BS5975:2008 Safe Working Load - BS EN 1065 props erected 1o out-of-plumb with 10mm eccentricity of load

6 of 6

BS 5975:2008

Check Two

Lateral Stability

BS 5975:2008

Check Two

Lateral Stability

BS 5975 : Horizontal Disturbing Force Clause 19.2.9.1

At each phase of construction falsework should resist the applied vertical loads PLUS a horizontal disturbing force the greater of EITHER

2½% WOR the summation of

wind force, erection tolerance ( 1% W) , concrete pressure force,water and wave forces, dynamic and impact forces, forces fromthe permanent works (e.g. stressing etc.) etc..

1 Of 2

Falsework’s horizontal disturbing force F H

Design for minimum lateral stability load of

2½% W

Load W

or

known lateral loads

PLUS 1%W

2 of 2 (BS 5975 : Clause 19.2.9.1 )

Load Case 1 - Erected but not concreted

Lateral Forces :-

Maximum wind load

plus

Increases to at least 2% of known vertical

loads if Class B2

1% known vertical loads(BS 5975 and Class B1)

Load Case 2 - While placing the permanent work / concrete

Lateral Forces :-

Working wind load

plus

Increases to 2% known vertical loads if Class B2

1% known vertical loadsincluding full concrete load

(BS 5975 and Class B1)

NOTE: If the structure is not connected to a permanent structurethen the full wind load might need to be considered

- consult with the Temporary Works Designer (TWD )

UK BS 5975 load Case - Minimum stability

Horizontal disturbing force FH will bea minimum of

2½ % total vertical load including

self weight, concrete, and full construction operations load

Top Restrained Load Case - connected toPermanent Works

Restraining force RHwill be a minimum of:-

2½ % (vertical loads)(BS 5975 and Class A)

or2 % (self weight)

plus maximum wind(Class B2)

or2 % (vertical loads) plus working wind(Class B1 and B2)

NOTE: Although bracing is not shown, thestructural strength still needs checking(Cat. 2) and bracing may be required to create effective nodes.

Conditions of use stated by

supplier require top restraint

1 of 3

2 of 3

3 of 3

North Staffs PFI SGB GASS braced for 2½ % W

Or is it ?Top restrained falsework

Lateral Stability of steel beams - Web stiffeners

For structural steelwork at points of reaction or concentrated load, web stiffeners should be

provided at ALL loading transfer points including supports, UNLESS calculations are provided to

show that such stiffeners are not required.

Web stiffenersNo Calculations

(BS 5975 : Annex J Clause J.1)

BS 5975:2008

Back proppingflat slabs

BS 5975:2008

Back proppingflat slabs

Falsework

Formwork

Backpropping

European Concrete Building Project (ECBP) - 4th floor1 of 1

Method One - One level of backpropping

NEW Slab to be castFalsework load (wp )

Supporting slab (1)

Backprops (wb1 )

Lower slab (2)

Distribution of Applied Load using Rigid Props

SLAB PROP

100%100%

50%

50%

50%

Distribution of Applied Loadsusing Elastic Props

SLAB PROP

100%100%

70%30%

30%

This is 70% of the applied load

and is in additionto the existing

load on the slab

With preloaded propsto value Pp

- Pp

+ Pp

+ Pp

BS 5975 Cl 19.3.4 Table 20

Method One - Two levels of backpropping

NEW Slab to be castFalsework load (wp )

Supporting slab (1)

Upper Backprops (wb1 )

Lower slab (2)

Lower Backprops (wb2 )

Lower slab (3)

Distribution of Applied Loadsusing Rigid Props

SLAB PROP

100%100%

33%

67%

33%

33%

33%

Distribution of Applied Loadsusing Elastic Props

SLAB PROP

100%100%

65%35%

23%

12%

12%

With preloaded props to value Pp

- Pp

+ Pp

+ Pp

+ Pp

This is 65% of the applied load

and is in additionto the existing

load on the slab

BS 5975 Cl 19.3.4 Table 20

Part Two - Changes since 2009

(c) Scaffolding

Part Two - Changes since 2009

(c) Scaffolding

Temporary construction, which is required to provide a safe place of work for the erection, maintenance, repair or

demolition of buildings and other structures and for the necessary access

Harsco Infrastructure

BS EN 12811-1 : 2003

Part 1: Scaffolds -Performance

requirements and general design

Published June 2004

£182.00

Chairman: CEN TC 53

“States BS 5973 withdrawn”

BS EN 12811-1Introduces:-

TWO Load Combinations :

In Service Condition

One platform with fullimposed service load

andthe next above or below with 50% of service load

Plus in absence of wind a lateralforce of 0.3 kN / bay / working area

Out of Service Condition

Full wind load (BS EN 1991-1-4)and imposed Service Load limited to only 25% or 50%

NASC Guide for Scaffolding with

tubes and fittings

TG20:08 Volume 1

November 2008120 pages

Authors: Dr M.H.R. GodleyEur Ing P.F. Pallett

Based on BS 5973 and updated to BS EN 12811-1 with simplified

BS 6399 wind information

Information for erection and use of standard scaffolds and

includes FOUR summary tables of safe heights for scaffolds

£135 + p&p Vol 1 & 2Source : NASC1 of 4

TG20:08 Volume 2 November 2008128 pages

TECHNICAL DATA

Information on weights and properties, additional wind info., worked examples, and method for height of unclad scaffolds.

Safe Height tables for :-

3 tables fully loaded inside boards3 tables part ledger braced scaffolds

Fuller calculation method heights: 24 tables fully ledger braced

12 tables part ledger braced (alt. ties)

£135 + p&p Vol 1 & 22 of 4

TG20:08 Supplement 1 February 2011

16 pages

Takes account of the Wind Code

BS EN 1991-1- 4:2005 + A1:2010

using a simplified method to update the SAFE HEIGHT tables

for Basic Scaffolds

Incorporates Apprendix H for use of ties on UNCLAD scaffolds

erected to open structures.

Source : NASC3 of 4

TG20:08 OverviewTOOLBOX TALK

Published by National Access and Scaffolding Confederation

in July 2009

Plus a FREE Powerpoint toolbox presentation from

www.nasc.org.uk

£2.50Handy Pocket Sized booklet

Available from NASC4 of 4

SG4 : 10Preventing Falls in

Scaffolding

Published by National Access and Scaffolding Confederation

with Foreword by HSE in December 2010

£2560 pages

Available from NASC1 of 5

SG4 : 10No longer permitted to traverse along a platform (known as tunnelling method)

Create “scaffolders safe zones”

For scaffolds with 2m lifts use of Step-ups

Figure 39 2 of 5

Erection hop-upfor next guardrail

Quick release connection

3 of 5

SG4 : 10Introduces use of ‘Scaffolders Safe Zone’

Reaching below guardrail “clip-on”

Figure 9Figure 12

4 of 5

SG4:You User Guide

Preventing Falls in Scaffolding

Published by National Access and Scaffolding Confederation

with Foreword by HSE

( 84pp January 2011)

Handy Pocket Sized booklet £5

Available from NASC5 of 5

Designation of Scaffolds to TG20:08

EXAMPLE

3 – 5 - 1

Load Class 3(General Purpose)

Number of boardsbetween standards

Number of inside boards ( 0, 1 or 2)

Inside boards assumed lightly

loaded

F

Inside boards fully loaded

I.e. Load Class

S

Special case with 1.8m bay length

TG20 Cl 4.2 page 19

BASIC Scaffolds to TG20 Guide to T&F Scaffolds

Part Boarded Fully Boarded2 m lifts with possible

2.7m pavement lifts

Tied to the building façade: either at alternate lifts 4m

or at every lift

Ledger bracing at alternate bays

Façade bracing fitted every SIX bays but note:

Plan bracing needed every FOURlifts, and every twelve bays

if façade braced across single bay

The controlling Table 1

Load Desigtion Activity Load M ax Max Class kN/m² Bay Boards

1 1 - 3 - 0 Inspection, v. light duty 0.75 2.7m 3

2 2 - 4 - 0 Light duty 1.50 2.4m 4

3 3 - 5 - 0 General purpose 2.00 2.1m 53 - 4 - 13 - 4 - 23 - 5 - 13 - 5 - 2

4 + 14 + 25 + 15 + 2

( inside boards are 0.75 )

4 - 4 - 14 - 4 - 24 - 5 - 14 - 5 - 2

4 + 14 + 25 + 15 + 2

4 4 - 5 - 0 Heavy Duty 3.00 1.8m 5

( inside boards are 0.75 )

Source TG20:08 Vol. 1 Table 1 page 21

TG20 Figure 1 page 18

Typical independent tied scaffold

Tie assembly

Façade bracing everySIX bays - to top platform

Ledger bracing alternate baysTies shown at alternate lifts

Plan bracingNOT requiredPlan bracingNOT required

1 of 2

Tie assembly

Façade bracing everySIX bays - to top platform

2 of 2

Plan bracing REQUIRED between ties as façade brace is NOT between ledger braced frames

H > 8m every FOUR liftsand every twelve bays

1 of 1

One transom at every lift within300mm of ledger braced standards fitted with right angle orswivel fittings

Ledgerbracing

Tie assembly

TG20 Cl. 10.2 (page 51)

ALL sheeted & debris netted - unclad over 15m

Part Three : Changes in 2011

(a) Wind(b) Formwork

Part Three : Changes in 2011

(a) Wind(b) Formwork

Part Three : Changes in 2011

(a) Temporary Works Wind

Part Three : Changes in 2011

(a) Temporary Works Wind

Status of Wind Codes in the UK

BS 6399-2: 1997 Loading for buildings, Part 2: Code of practice for wind loads, was published in July 1997

TG20 (scaffolding) first published in 2005 a simplified method based on BS 6399-2

Supplement No. 1 uses BS EN 1991-1-4+A1The European Code BS EN 1991-1-4:2005+A1:2010

was amended in March 2011 (£246)The UK National Application Document (£170)

was also amended in March 2011

The Background Information PD 6688 (£182)to the Annex was published in December 2009

ALL British Standards superseded by European Standards were withdrawn on 31st March 2010

Wind in Temporary Works

Aim: same procedure in all temporary works

Falsework - BS 5975:2008 +A1:2011 to introducerevised simplified method based on the UK NA to BS EN 1991-1-4 +A1

Scaffolding - TG20 Supplement No. 1 now issued

Formwork - Revision will include the same methodextended to suit climbing formwork.

Duration of work (assume less than two years)

Simplified method will use similar factors and town descriptions as existing for

structures less than 50m with “orography”and less than 100m without “orography”.

Information needed by designer

Location of the site

How far from the nearest sea? less than 0.1km, 2 km, 10 km or 100 km

Is it in a town that extends more than 2 km fromthe site in all directions?

Is the topography fairly flat around the site, or is itnear the top of the hill, or part-way up ?

What is the altitude of site? (in metres above sea level)

Duration of work (normally less than two years)

Is the falsework or the scaffold to be unclad, debris netted or sheeted?

Maximum wind pressure on falsework and formwork

2windTe,ep S (z)cc 613.07.0q ×××=

qp is the peak wind pressure N/m²

Swind is the wind factor for the site

Ce(z)ce,T is combined exposure correction factor

Where

Formula is for falsework erected less than TWO years

Source BS 5975:2008 +A1:2011 (Cl 17.5.1.3) and BS EN 12812 (Cl 8.2.4.1)

The wind factor Swind

⎟⎠⎞

⎜⎝⎛ +××=

1000A1TvS windmapb,wind

Where

vb,map is the fundamental wind velocity (in m/s)

Twind is the topography factor allowing for whether site is on a hill, cliff or on the flat.

A is the altitude of the site in metres above sea level.

1 of 8

Mean hourly wind speeds

BS 5975:2008 Figure 42 of 8

10 minute mean wind speeds vb,mapb,map

NA to BS EN 1991-1-4

Twind = Topographical factor dependson whether the terrain around

the site is flat, moderately steep (1 : 5 ) or very steep (1 : 3 )

Structures without “orography” Twind = 1.00 (z < 100m)

BS 5975 Figure 5 (a)3 of 8

Topography Factor Twind

Skip wind

SEA

Definition of ‘sea’ from BS 6399

BS 5975:2008 Figure 74 of 8

TOWN

Built up areas

BS 5975:2008 Figure 6 (a) 5 of 8

“TOWN” Woodland areas

BS 5975:2008 Figure 6 (c)6 of 8

COUNTRYYou’ll like this one !

Country is all terrain which is not sea or town !

Less than 2km of built-up area around the site.

7 of 8

COUNTRY

Built up areasBS 5975:2008 Figure 6 (b)

8 of 8

Part Three : Changes in 2011

(b) Formwork

Part Three : Changes in 2011

(b) Formwork

A structure, usually temporary, but in some cases wholly or partly permanent

used to contain poured concrete to mould it to the required dimensions and support

it until it is able to support itself.

It consists primarily of the face contact material and the bearers that directly

support the face contact material.

Published by The Concrete Society

Second Edition: June 1995

Revised

due 2011

Chairman: Peter Pallett

Skip to TWf

More emphasis on proprietary panel formwork

More guidance on Soffit Formwork systems

New Sections on Climbing Formwork

Peri

Update on Permanent Formwork - e.g. Twin wall

1 of 2

2 of 2

Significant updates to sections on:-

Surface finishesand tolerances

toBS EN 13670“Execution of

concrete structures”

Striking and Curing

BS EN 1992-1-1:2004: Eurocode 2: Design of concrete structures. General rules and rules for buildingsdoes not cover surface finishes (replaces BS 8110)

BS EN 13670: 2010 Execution of concrete structures. Includes informative guidance (£186 Feb 2010)

Annex F Table F.4 Types of surface finish

Basic Finish Where no particular requirement needed

Ordinary Finish Where not of visual importance.e.g. unseen areas such as lift shafts

Plain Finish Visual effect of some importancee.g. Seen occasionally, direct painted etc.

Special Finish Where special requirements needed.e.g. Where surface irregularity and colour are

important.

Concrete Pressure envelope when placed from top

0 Max Dh

Pmax

Concretestiffening

Pmax

Design formwork pressures for a range of new cements and self-compacting concretes

DTI Contract Ref: 39/3/739 CCC2399

September 2004 133 pages

Quote: “ The findings indicate that the

use of CIRIA R108 was conservative for the range of new concrete types for walls

and columns. There appears to be no case

for change from the existing UK approach to concrete pressure

determination.”

NOTE: The report is confidential and NOT available to the public.See article in “CONCRETE” March 2009

Concrete Groups and the values of C2

Group Concrete C2

2. With any admixture except with retarding property 0.3CEM I , SRPC, CEM II A with metakaolin / silica fume

1 of 2

Self-compacting - With any admixture except with 0.45retarding properties.

ALL cements except CEM III B & CEM IVB

5. With any admixture except with retarding property 0.45CEM II A, CEM II B, CEM III A

3. With admixtures that retard - CEM I (OPC), SRPC, 0.45CEM I I A with metakaolin or with silica fume

4. Without admixture - CEM II A, CEM II B, CEM III A 0.45

1. Without admixture - CEM I (OPC) , SRPC, 0.3CEM II A with metakaolin or with silica fumeA

basic

Bretarded

Concrete Groups and the values of C2

Group Concrete C2

6. With admixtures that retard 0.6CEM II A, CEM II B and CEM III A

Cheavily

retarded

7. With or without admixtures 0.6CEM III B and CEM IVB

Self-compacting - With any admixture except with 0.6retarding properties.

CEM III B & CEM IVB

Self-compacting - With retarding properties 0.6ALL cements

2 of 2 Source: CIRIA R108 and March 2009 “CONCRETE”

2m 35 40 45 45 50 50 503m 40 45 50 55 60 70 75

10°C 4m 45 50 55 60 65 75 905m 45 55 60 60 70 80 1006m 50 55 60 65 75 85 105

4m 30 35 45 45 50 65 8520°C 5m 35 40 45 50 60 70 90

6m 35 40 45 50 60 70 90

Rate of Rise R in metres per hour0.5 1.0 1.5 2.0 3.0 5.0 10.0HTable AA

WALLS & BASESPmax max (kN/m²)

Basic ConcreteGroup A(1) CEM I

(OPC)or

(2) CEM I withadmixture

2m 40 45 50 50 50 50 503m 50 55 60 65 70 75 75

5 °C 4m 55 60 65 70 75 85 1005m 65 65 70 75 80 95 110 6m 70 75 80 80 90 100 115

2m 30 35 40 45 50 50 503m 30 40 45 50 55 65 75

15°C 4m 35 45 50 50 60 70 905m 40 45 50 55 60 70 906m 40 45 50 55 65 75 95

PFP/002E page 8

increase 4555

5580 %=−

Table BBWALLS & BASES

Pmax max (kN/m²)

2m 40 45 50 50 50 50 503m 50 55 60 65 65 75 75

10°C 4m 55 60 65 70 75 85 1005m 60 70 70 75 80 90 1006m 65 75 75 80 85 95 115

4m 40 45 50 55 60 70 9020°C 5m 40 45 50 55 65 75 95

6m 45 50 55 60 70 80 100

Rate of Rise R in metres per hour0.5 1.0 1.5 2.0 3.0 5.0 10.0H

Retarded ConcreteGroup B

(3) CEM I withretarder

(4) Blend with<35% pfa

or <65%ggbs(5) Blend <35% pfa

<65% ggbs withadmixture

2m 50 50 50 50 50 50 503m 65 70 75 75 75 75 75

5°C 4m 75 80 85 90 95 100 1005m 85 90 95 95 105 110 1256m 95 100 100 105 110 120 135

2m 35 40 45 45 50 50 503m 40 45 50 55 60 70 75

15°C 4m 45 50 55 60 65 75 905m 50 55 60 65 70 80 1006m 50 60 65 65 75 85 105

PFP/002E page 9

Sustainable ForestsWhere timber is used in formwork, it is recommended that only material which is certified under the Forest

Stewardship Council scheme should be used.

This ensures that timber is sourced from FSC certified forests which are managed sustainably.

There is a “Chain of Custody” which tracks

the timber from forest to consumer.

Source www.fsc.org

Safe Working Properties - Timber in Wall formwork

Source: Third Edition Formwork Guide ( PFP/009A page 4 of 18 )

Formwork to precast edge forms

Source: New Table 10 Formwork Guide (Third Edition)

Safe Working Properties - WALL Formwork

and finallyand finally

T W fT W f

Temporary Works forumPromoting Temporary Works in the Construction Industry

by : Institution of Civil EngineersInstitution of Structural EngineersHealth and Safety ExecutiveStanding Committee on Structural SafetyChartered Institute of BuildingTW Equipment SuppliersConsulting EngineersContractors

Remit: Authoritative guidance, profesional leadership,interfaces PW & TW, current trends, warningson unacceptable risks, recommend researchareas, watching brief on overseas issues

www.twforum.org.uk

Thank You

The End