3-Australian Standard 3610 formwork for concrete

3.4.5 Precast concrete elements 3.4.5.1 General The following shall apply to precast concrete: a Clause 3.4.4, as appropriate, for the specified class of surface finish except for thetol

AS 3610—1995

Formwork for concrete

published on 5 April 1995.

The following interests are represented on Committee BD/43:

Aluminium Development CouncilAustralian Federation of Construction ContractorsAUSTROADS

Building Management Authority of W.A

Cement and Concrete Association of AustraliaDepartment of Employment, Vocational Education, Training and IndustrialRelations

Department of Occupational Health Safety and Welfare, Western AustraliaFormworks Contractors of W.A

Housing Industry AssociationMetal Trades Industry Association of AustraliaNational Precast Concrete Association AustraliaPlywood Association of Australia

Queensland University of TechnologyThe Association of Consulting Engineers AustraliaWorkcover Authority of N.S.W

Review of Australian Standards To keep abreast of progress in industry, Australian Standards are subject

to periodic review and are kept up to date by the issue of amendments or new editi ons as necessary It is important therefore that Standards users ensure that they are in possession of the latest editi on, and any amendments thereto.

Full detail s of all Australian Standards and related publi cati ons wil l be found in the Standards Australi a Catalogue of Publications; this information is supplemented each month by the magazine ‘The Australi an Standard’, which subscribing members receive, and which gives detail s of new publications, new edit ions and amendments, and of withdrawn Standards.

Suggesti ons for improvements to Australian Standards, addressed to the head off ice of Standards Australi a, are welcomed Notif ication of any inaccuracy or ambiguit y found in an Australi an Standard should be made without delay in order that the matter may be investigated and appropriate action taken.

AS 3610—1995

Formwork for concrete

PUBLISHED BY STANDARDS AUSTRALIA

This Standard is a new edition of AS 3610 — 1990 and incorporates a number of changes andcorrections to the previous edition, specifically in Clauses 1.3, 1.6, 3.4.5.2, 4.5.5.3, 4.5.6.3,4.6.3, 5.4.3.2, 5.4.4 and 5.6.4.2; Paragraphs A4.4.3, A4.4.4, A5.3 and A6; Tables 3.4.1, 3.4.2,4.4.1, 4.5.1, 4.5.2, 4.5.3, 4.5.4, 5.3.1 and 5.4.2; and Figure 5.3.1

The objective of this Standard is to set out requirements for the design, fabrication, erectionand stripping of formwork as well as evaluation of the formed concrete surface

Where mandatory notes to tables are used in this Standard, they are deemed to form anintegral part of the Standard

Photographic charts for the assessment of colour and surface finish are provided in theappendices Additional copies of these charts are available as AS 3610, Supplement 1

AS 3610 Supplement 2 provides a commentary on this Standard The commentary includesbackground information on the Standard, guidance on its use, and suggestions on goodpractice

The term ‘normative’ has been used in this Standard to define the application of the appendix

to which it applies A ‘normative’ appendix is an integral part of a Standard

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Page

1.1 SCOPE 4

1.2 APPLICATION 4

1.3 REFERENCED DOCUMENTS 4

1.4 NEW MATERIALS OR METHODS 5

1.5 DEFINITIONS 5

1.6 NOTATION 8

SECTION 2 THE PROJECT DOCUMENTATION 2.1 SCOPE OF SECTION 10

2.2 GENERAL 10

2.3 INFORMATION TO BE PROVIDED IN THE PROJECT DOCUMENTATION 10

SECTION 3 SURFACE FINISH 3.1 SCOPE OF SECTION 12

3.2 APPLICATION OF SECTION 12

3.3 CLASSES OF SURFACE FINISH 12

3.4 PHYSICAL QUALITY 12

3.5 COLOUR CONTROL OF UNTREATED SURFACES 17

3.6 TEST PANELS 20

SECTION 4 STRUCTURAL DESIGN AND DOCUMENTATION 4.1 SCOPE OF SECTION 22

4.2 APPLICATION OF SECTION 22

4.3 DESIGN REQUIREMENTS 22

4.4 LOADS 23

4.5 ANALYSIS AND DESIGN 31

4.6 CONSTRUCTION CONSIDERATIONS 36

4.7 FORMWORK DOCUMENTATION 37

SECTION 5 CONSTRUCTION 5.1 SCOPE OF SECTION 39

5.2 APPLICATION OF SECTION 39

5.3 GENERAL FORMWORK REQUIREMENTS—IN SITU CONCRETE 39

5.4 FORMWORK CONSTRUCTION—IN SITU CONCRETE 40

5.5 FORMWORK CONSTRUCTION—PRECAST CONCRETE 46

5.6 EVALUATION OF COMPLETED WORK AND REPAIRS 46

APPENDICES A TESTING OF FORMWORK 52

B BLOWHOLE AND COLOUR EVALUATION CHARTS 59

STANDARDS AUSTRALIA

Australian Standard Formwork for concrete

1.1 SCOPE This Standard sets out requirements for the design, fabrication, erection andstripping of formwork, as well as the specification, evaluation and repair of the quality of theformed concrete surface and the influence of this activity on the design and construction of

an in situ concrete structure Design by testing is considered separately, the requirementsbeing set out in Appendix A Some Sections of the Standard are also applicable to precastconcrete, in particular some aspects of Sections 3 and 5

This Standard does not apply to unformed concrete surfaces, e.g tops of slabs

1.2 APPLICATION Formwork requirements in the project documentation shall complywith Section 2 The concrete surface finish shall comply with Section 3 The structural design

of formwork shall comply with Section 4 The procedures to be followed in construction,checking the completed work and carrying out repairs shall be in accordance with Section 5

1.3 REFERENCED DOCUMENTS The documents below are referred to in thisStandard:

1720 Timber Structures (known as SAA Timber Structures Code)

2082 Visually stress-graded hardwood for structural purposes

2271 Plywood and blockboard for exterior use

2858 Timber — Softwood — Visually stress-graded for structural purposes

3700 Masonry in buildings (known as the SAA Masonry Code)

Report 108 Concrete Pressure on Formwork (published by the Construction Industry

Research and Information Association (UK))

1.4 NEW MATERIALS OR METHODS Provided the requirements of this Standard aremet, this Standard shall not be interpreted to prevent the use of materials or methods ofdesign or construction not specifically referred to herein.

1.5 DEFINITIONS For the purpose of this Standard, the definitions below apply

1.5.1 Administrative definitions

Engineer — a person qualified for Corporate Membership of the Institution of Engineers,

Australia, and with experience in the area of formwork

NOTE: The definition of ‘Engineer’ does not require that an Engineer be a Corporate Member ofthe Institution of Engineers, Australia

Formwork documentation — drawings, specifications, brochures and associated documents that

describe the formwork assembly to be erected

May — indicates a practice which complies with the requirements of this Standard.

Project documentation — drawings, specifications and associated documents that describe the

permanent structure to be constructed

Regulatory authority — a body having statutory powers to control the design and erection of

the formwork

Shall — indicates a mandatory statement to be adopted in order to comply with this Standard.

1.5.2 Technical definitions

Adjustable prop (also called ‘telescopic prop’) — a prop (see ‘prop’) capable of coarse and

fine adjustment of its overall length

Backpropping — process by which adjustable supports are placed to give support to the

permanent structure during the removal of the formwork to the soffit (See Figure 1.5.1.)

Bearing area — effective area over which a force is transferred to a supporting structural

system

Blowhole — indentation in the formed surface of the concrete caused by a bubble of fluid or

air trapped against the form surface

Bracing — secondary structural members which normally do not support gravity loads but are

required to provide lateral stability to other structural members or to transfer horizontal loads

to supports

Camber — the intentional curvature of formwork prior to concrete placement to compensate

for the deflection of the formwork or the permanent structure under load

Cast-in-situ concrete — concrete which is placed, as plastic concrete, in its final location as

part of the permanent structure

Class of surface finish (or ‘Class’) — standard of the untreated concrete surface of the formed

concrete

Continuously moving formwork — system of forms where a mechanism is provided to

continuously relocate the form surface as the concrete is placed also known as slipform

Construction joint — a joint, including a joint between precast segments, that is located in a

part of a structure for convenience of construction and made so that the load-carryingcapacity and serviceability of the structure will be unimpaired by the inclusion of the joint

Deflection — flexural movement of a structural member or assembly in response to the forces

acting on it

Deviation — distance between the actual location of a point in the permanent structure and

the specified position of that point

Element — portion of the permanent structure delineated by formed concrete faces,

construction joints and the completed concrete surfaces, which is poured in one continuousoperation

Footing — part of the formwork or permanent structure in direct contact with, and transmitting

load to, the supporting foundation

Form — that part of the formwork on which the plastic concrete is poured It consists of the

form face and the framing to the form face

Form face — that part of the form which comes direct contact with the plastic concrete Form face deflection — the undulation of the concrete surface resulting from the deflection

of the form face

Form face span — the distance between any two adjoining and parallel members which

support the form face

Form lining (also called ‘form liners’) — non-structural material placed on, or part of, the

form face to achieve a desired surface finish

Form tie — also called ‘wall tie’ or ‘tie rod’, a device which penetrates a form, extends

through the permanent structure and restrains the form from movement due to concretepressure

Formwork — the surface, supports and framing used to define the shape of concrete until it

is self-supporting

NOTE: This term includes the forms on which the concrete is poured, the supports which withstandthe loads imposed by the forms and the concrete, the bracing which may be added to ensurestability, and the footings When complete the formwork can be known as the formwork assembly.Supports and bracing mentioned above are sometimes known as falsework

Formwork assembly — an assembly of formwork components including footings which

together constitute a structure

Foundation — soil, subsoil or rock, whether built up or natural, upon which the permanent

structure or the formwork is supported

Grout loss (also called ‘mortar loss’) — the loss of fine material, cement and fine aggregate,

from plastic concrete due to openings in the form face

Hog — negative deflection of concrete elements under the effect of prestressing.

Hydration staining — darker areas in the formed surface caused by reduced hydration of the

cement when moisture is lost either by leakage from the formwork or by absorption into theform face

Hydrostatic pressure — theoretical pressure which would be exerted on the forms by a fluid

of the same specific gravity as plastic concrete

Permanent structure — the structure for which the formwork is required.

Plastic concrete — freshly mixed concrete that has not yet achieved any initial setting.

Precast concrete — concrete which is placed, as plastic concrete, in a location other than in

its final location as part of the permanent structure

Progressive collapse — a type of failure in which the collapse of one component leads to

overload of adjacent components resulting in further collapses

Prop — a structural member loaded in compression.

Proprietary item — an item made in quantity production for general use in formwork

assemblies, and whose load capacity has been proven by analysis or test

Reshores — adjustable supports placed to give support to the permanent structure after the

formwork to the soffits in the area has been removed

Soffit formwork — formwork to the undersides of slabs, beams and the like.

reinforcement, which temporarily loads either the formwork assembly or the previouslyplaced concrete

Stripping — also called ‘striking’, the removal of forms from the surface of the hardened

concrete

Supports — the formwork components that transmit all or part of the loads to a lower level.

This term includes undisturbed supports, backprops and reshores

Surface treatment — the removal of a specified depth of the concrete of the permanent surface

by a nominated mechanical means such as sand blasting or jack picking This does notinclude applied finishes such as coatings or paint

Test panel — a concrete element constructed, prior to the commencement of the permanent

structure, as an example of materials and quality of work

Tolerance — acceptable limits for deviation.

Tonal scale — the graded set of grey tones provided in this Standard, or prepared by the

project designer when special concrete is used, for evaluation of the colour of the concretesurface

Undisturbed support — compression member which, as part of a soffit formwork, remains

undisturbed in place until the permanent structure is strong enough to support itself eventhough the forms have been removed earlier (See Figure 1.5.2.)

FIGURE 1.5.2 UNDISTURBED SUPPORTS

1.6 NOTATION The following notation is used in this Standard:

a = an offset measured for the purpose of assessing concrete surface undulations (see

Clauses 3.4.4 and 5.6.2.2(d))

B = out-of-plumb offset for testing of compression members (see Paragraph A3.1)

b = an offset measured for the purpose of assessing concrete surface undulations (see

Clauses 3.4.4 and 5.6.2.2(d))

bp = stiff portion of bearing of an end plate (see Clause 4.4.3)

C = a suffix used in the specification of concrete colour (see Clause 3.3.2)

C1 = a coefficient used in the calculation of lateral concrete pressure (see Clause 4.4.5.1)

C2 = a coefficient used in the calculation of lateral concrete pressure (see Clause 4.4.5.1)

D = overall depth of section of a concrete member (see Clause 5.4.3.2(a))

e = total eccentricity of load on struts (see Clause 4.4.3)

e′ = a fixed eccentricity of load on struts (see Clause 4.4.3)

e′′ = an expected eccentricity of load on struts (see Clause 4.4.3)

Fps = design load for design in accordance with the ‘permissible stress’ approach (see

Clause 4.5.5.3)

F′ps = load-carrying capacity of a formwork structure or component for design in

accordance with the ‘permissible stress’ approach (see Clause 4.5.5.3)

fcm = the mean value of the compressive strength of concrete at the relevant age

G = dead load (see Clause 4.4.2.1)

Gc = concrete load (see Clause 4.4.2.2)

H = vertical form height used in the calculation of lateral concrete pressure (see Clause

4.4.5.1)

h = vertical pour height used in the calculation of lateral concrete pressure (see Clause

4.4.5.1)

HL = lateral load on struts due to buckling restraint (see Clause 4.4.6)

I = horizontal impact load (see Clause 4.4.5.3(c))

K = temperature coefficient used in the calculation of concrete pressure (see

Clause 4.4.5.1)

kd = modification factor applied to strength, used in the determination of a test load for

non-destructive evaluation (see Paragraph A5.4)

kdi = modification factor for duration of load on timber members or formwork assemblies

(see Paragraph A4.4.3)

ks = sampling factor used in the determination of a test load for non-destructive

evaluation (see Paragraph A5.4)

L = the overall length of the strut or assembly of struts (see Clause 4.4.3)

l = length of straight edge (see Table 3.4.2 and Figure 5.6.4)

M1 = load from stacked materials during Stage I of the construction cycle (see

P = load due to lateral concrete pressure (see Clause 4.4.5.1)

Pmax = maximum lateral concrete pressure exerted on formwork (see Clause 4.4.5.1)

Pv = axial force in a compression member used for the calculation of a load due to

buckling restraint (see Clause 4.4.6.2(b))

Q = live load (see Clause 4.4.2.3)

Qc = concentrated live load (see Clause 4.4.2.3)

Quh = horizontal live load (see Clause 4.4.5.3(a))

Quv = uniformly distributed vertical live load (see Clause 4.4.2.3)

R = rate of vertical rise in the placement of concrete, for the calculation of lateral

concrete pressure (see Clause 4.4.5.1)

Ru = ultimate strength of a material and assembly, or assembly alone, for the

determination of strength limit states (see Clause 4.5.4.3)

S* = design action effect, used in limit-state calculations (see Clause 4.5.4.3)

St = test load for non-destructive evaluation of formwork components (see

Paragraph A5.4)

s = standard deviation of a finite population of formwork items tested to destruction (see

Paragraph A4.4.2)

T = temperature of the concrete at placement (see Clause 4.4.5.1)

V = coefficient of variation for the failure load of a formwork component or assembly

made of a particular material and loaded in a particular manner (percent) (seeParagraph A4.4.2)

Wp = wind load used for permissible stress design procedures (see Clause 4.4.5.4)

Wu = wind load used for limit states design procedures (see Clause 4.4.5.4)

X = a suffix used in the specification of surface finish for concrete, denoting a less

stringent value or additional feature (see Clause 3.3.2)

Xw = a load due to water (river currents, tidal or wave action) (see Clause 4.4.5.5)

Xi = test result of each individual unit of the sample (see Paragraph A4.4.2)

= mean value of the test results of the accumulated sample of units (seeParagraph A4.4.2)

The project documentation shall always include a description of the concrete element and anyconditions relating to its production.

2.3 INFORMATION TO BE PROVIDED IN THE PROJECT DOCUMENTATION

Project documentation shall cover any matters associated with the formwork construction,concrete placement or formwork removal, and which are critical to the serviceability of thepermanent structure In addition to the description of the concrete element, the followingshall be specified or indicated in the project documentation, where applicable:

(a) Minimum formwork stripping times and stripping procedures

(b) Any limitations on the magnitude and locations of stacked materials and minimumconcrete strength to be achieved prior to the stacking of materials This will be 4 kPaunless otherwise specified (see Clause 4.4.2.4)

(c) Requirements for the minimum number of levels of supports relative to the type offormwork, timing and sequence of its use, the anticipated time between construction

of subsequent floors and the expected ambient temperature for multistorey structures.(d) Limitations on the use of the permanent structure for the restraint of formwork.(e) Details of and information on the effect of the post-tensioning procedures on theformwork and any special procedures to be adopted in the stripping of formwork.(f) Location of any mandatory joints and any special procedures for locating other joints.(g) Sequence of placement of the concrete if this is critical

(h) Requirements for propping of any composite construction

(i) Details of the cambering of any slabs of beams

(j) Design loads for the permanent structure

(k) Details of any inserts, waterstops, specially formed shapes or penetrations to beconstructed, the location and details of which are critical to the serviceability of thepermanent structure

(l) Any known information about the foundation which is relevant to the design of thefootings for the formwork assembly

(m) Information about any permanent formwork systems, together with any limitations ondeflections and any special requirements for their erection and concreting

(n) Information on the critical face of elements (see Clause 3.4.3.3), any special measuringpoints and more stringent tolerances for any small areas (see Table 3.4.2)

(o) The details set out in Table 3.4.1 relating to surface finish, colour control, surfacetreatment, critical elements, tolerances and repairs where relevant for all surfaces of thepermanent structure.

(p) Details of any special-class concrete required under Clause 3.5.2 with the tonal scale

to be used under that Clause if the concrete colour is unsuited to the tonal scaleprovided in Appendix B

(q) Where an ‘X’ suffix is used as defined in Clause 3.3.2, all relevant information relating

to Tables 3.4.1 and 3.4.2

(r) Details of test panels (See Clause 3.6 and Clause 5.6.2.1(c).)

(s) Information on any architectural details to be cast into the structural concrete

S E C T I O N 3 S U R F A C E F I N I S H

3.1 SCOPE OF SECTION This Section covers the classification and specification of thephysical quality and colour for both in situ and precast concrete and the matters to be advised

in relation to these in the project documentation

3.2 APPLICATION OF SECTION This Section applies to —

(a) the surface finish and tolerances of formed and stripped concrete surfaces;

(b) the requirements for the project documentation related to surface finish as listed inSection 2; and

(c) the provision and use of test panels for both in situ and precast concrete

This Section does not apply to unformed concrete surfaces, or to the faces of concreteelements constructed from permanent formwork

3.3 CLASSES OF SURFACE FINISH

3.3.1 General There are five classes of surface finish The physical qualities of each ofthese classes, and their applicability, set out in Table 3.3.1

3.3.2 Notation The selected class of surface finish shall be denoted by the appropriatenumber from 1 to 5 Where colour control is incorporated this shall be denoted by thesuffix C following the surface finish class number (see Note 1) Where any additional feature(extra) is specified in the project documents, or values which are less stringent (see Note 2)than the values of physical quality assigned to the selected class, the suffix X shall be added(see Note 3) Except for small areas as stated in Table 3.4.2, Note 1, values more stringentthan those given for these classes shall not be specified

NOTES:

1 Attention is drawn to Clause 3.5 which disallows colour control for Classes 4 and 5

2 Attention is drawn to Table 3.4.2 which generally disallows the specification of values that aremore stringent than those assigned to the selected class

3 Examples: 2C denotes Class 2 with colour control 2X and 2CX are valid descriptors of surfacespecifications that have either extras or exceptions to the Standard

3.4 PHYSICAL QUALITY

3.4.1 General The physical quality of the concrete surface shall be specified under a classnumber in accordance with Table 3.3.1 If the class is not specified in the projectdocumentation the quality of the surface is not required to exceed Class 3

3.4.2 Project documentation requirements for surface finish The project documentationshall include, where appropriate, the information required in Table 3.4.1

3.4.3 Tolerances

3.4.3.1 General The tolerances given in this Section shall be read in conjunction withthose given in AS 3600 These tolerances apply to the as-cast formed surface prior to surfacetreatment, if any

NOTE: The tolerances in AS 3600 result from structural considerations, and may, in someinstances, be less stringent than those in this Section, which are concerned with surface finish andaccuracy

3.4.3.2 Measurement The tolerances given in this Section shall apply to the permanentstructure Other than for those cases where strain movement of the permanent concrete work

is anticipated, the deviations shall be measured on the surface of the concrete after removal

of any forms or supports and before any surface treatment Where strain movement of theconcrete is anticipated, they shall be measured prior to removal of any forms or supports.Evaluation of the completed work shall comply with the requirements of Clause 5.6.

NOTE: Requirements on the frequency and distribution of the measurement deviations are given

in Tables 3.4.2 and 3.4.3, and Clauses 3.4.5 and 5.6

3.4.3.3 Critical face Where a concrete element has several faces each with an equal class

of surface finish, the project documentation shall specify which faces take precedence in thechecking of deviations Where the opposite faces are of different classes then the face withthe higher quality shall take precedence in the checking

3.4.4 Acceptable surface defects and deviations Table 3.4.2 gives values for surfacedefects and deviations which represent the acceptable minimum quality appropriate to eachclass

3.4.5 Precast concrete elements

3.4.5.1 General The following shall apply to precast concrete:

(a) Clause 3.4.4, as appropriate, for the specified class of surface finish except for thetolerances on ‘flatness’ and ‘out-of-plumb’ given in Table 3.4.2 Where the shape of

a precast unit is such that there is conflict between the abovementioned Clauses andthose indicated in Item (b) below, Item (b) shall take precedence

(b) Clauses 3.4.5.2 and 3.4.5.3

3.4.5.2 Tolerance classification for precast concrete Tolerances for precast concrete shall

be classified as follows:

width, length and cross-section (see Figure 3.4.1)

or trueness to any specified angle (see Figure 3.4.2) Angular tolerance for squarenessshall be expressed in terms of the distance by which a shorter side of the precast unitdeviates from a straight line perpendicular to the longer side and passing through thecorner of the unit Trueness to an angle other than 90 degrees shall be expressed insimilar terms, but setting the check line in the specified angle

(c) Tolerances in profile Tolerances in profile cover flatness, straightness, warp and twist(see Figure 3.4.3), as indicated below:

(i) Flatness tolerance shall be expressed as the maximum permitted distance by

which any point on a nominally-plane surface may be from a 3 m longstraightedge placed anywhere on the surface and parallel to the nominally-planesurface

(ii) Straightness tolerance shall be expressed as the maximum distance by which any

point on an edge of a unit may be from a straight line drawn through theextremities of the particular edge

(iii) Warp tolerance shall be expressed as the maximum acceptable distance of any

point on a surface from a plane containing any three corners of the surface orpoints on the perimeter of the unit If the surface is not a rectangle these threecorners shall be those points on the surface which are the corners of a rectanglecovering the greatest possible surface area of the unit

(iv) Twist tolerance shall be expressed as the rotation of one end relative to the

other end or relative to some other line or surface specified by the projectdocuments

(d) Hog tolerance for prestressed concrete units For precast concrete units subject toprestressing, hog tolerance shall be specified The relevant deviations shall becalculated separately from those defined in (a), (b) and (c) above However, the effectsand range of hog tolerance shall be included in the total accumulative tolerance.

NOTE: The sequence for checking the above tolerance Clauses is defined in Clause 5.6.3.1

3.4.5.3 Tolerance values Precast concrete shall be manufactured within the acceptabledeviations given in Table 3.4.3

TABLE 3.3.1 APPLICABILITY OF SURFACE CLASSES

Visual

characteristics

Visual quality important Visual quality

not significant Highest quality

attainable.

Subject to close scrutiny.

Best possible uniformity of texture.

Excellent quality

of edge and joint details

Uniform quality and texture over large areas.

Built to close tolerances.

Consistently good quality of edge and joint details

Good visual quality when viewed as a whole

Texture not important.

Good general alignment

Alignment and texture not important

Suitable uses Selected small

elements.

Areas of special importance in limited quantities.

Elements contained in a single pour

General external and internal facades intended

to be viewed in detail

General external and internal facades intended

to be viewed as a whole

Surfaces concealed from general view.

Surfaces to have thick applied finishes after preparation

Totally concealed areas

Applied

finish

Not applicable Reference should be made to permitted tolerances prior to

selection of applied material

Not suitable

Situations where

not to be used

Trafficable slopes, soffits, formed tops of slopes except where means to dissipate entrapped air are employed, liners.

Is not applicable where treatment is

to 100% of surface

Formed tops of slopes except where means to dissipate entrapped air are employed

No restriction No restriction

Colour control May be specified Refer to Clause 3.6.3(b) for the limits of

the best colour consistency that can be expected

Excluded

General If these classes are required they must

be specified in the documentation

If these classes are not specified in the project documentation, selection of appropriate class is by the visual characteristics and suitable uses set out above

NO TE: Class 1 is the highest standard with the most rigorous specification and is only recommended for use in very special features of buildings of a monumental nature.

TABLE 3.4.1 PROJECT DOCUMENTATION REQUIREMENTS FOR SURFACE FINISH

Class 1 Class 2 Class 3 Class 4 Class 5 Ref.

TBS TBS TBS

OPT TBS TBS

NA NA NA

NA NA NA

3.6 3.6 3.6

3 Liner details, pattern and accuracy

3.3.1

4 Surface pattern details and accuracy

5 Surface treatment pattern of part of surface

8 Critical faces of elements SIA SIA SIA SIA EXCL 3.4.3.3

9 Distance between face steps OPT OPT OPT EXCL EXCL Table

3.4.2

10 Plumb of elements height ≥ 8 m

NA Not Applicable — these are matters which are not applicable to the particular class.

OPT Optional — these are matters which may be included in the project documents.

EXCL Excluded — these are matters which shall not be included in the project documents for the nominated class of surface finish.

SIA Specify If Applicable— these are mandatory where the particular feature is included in the project documentation.

AC C Acceptable — repairs to these classes are acceptable and shall not be excluded by the specification.

TABLE 3.4.2 ACCEPTABLE MINIMUM QUALITY OF SURFACE

Quality of surface finish Class 1 Class 2 Class 3 Class 4 Class 5 Ref.

Clause

1 Blowholes (Appendix B) Photo

1(a), 1(b)

Photo 2(a), 2(b)

Photo

2 Form face deflection Lesser of

2mm or span/360

Lesser of

3 mm or span/270

Greater of

3 mm or span/270

(b) at in situ construction joint 2 3 2 3 3 5 5 8 * *

2 The Table provides tolerances for surface finish which are generally more stringent than those given in AS 3600 The project documentation may also need to provide more stringent tolerances relating to deviations from specified positions and deviations

7 Unless otherwise specified, tolerances apply to in situ and precast concrete Refer also to Clause 3.4.2 Wider tolerances may

be specified for all classes by using the ‘X’ suffix, but limited by Note 5 above.

FIGURE 3.4.1 PRECAST CONCRETE — TOLERANCES IN LINEAR DIMENSIONS

NO TE: Out-of-squareness may affect measurement of tolerances in linear dimensions.

3.5 COLOUR CONTROL OF UNTREATED SURFACES

3.5.1 General The control of the colour of concrete surfaces may only be imposed onsurface finish Classes 1, 2 or 3 Colour control shall be evaluated before any surfacetreatment is carried out

NOTE: Attention is drawn to Clause 3.3.2 which describes the notation to be used when colourcontrol is specified

3.5.2 Concrete colour Where colour control is required, the concrete for this work shall

be specified as ‘special-class concrete’ in accordance with AS 3600 The projectdocumentation shall be consistent with the achievement of the required colour

NOTE: Methods for specifying concrete colour include tonal scales similar to that in Appendix B,Figure B4, for grey concrete, laboratory samples, test panels, etc

3.5.3 Range of tonal variations For concrete which is grey in colour the tonal scale inAppendix B may be used For concrete of other colours or where the grey is not within therange of Figure B4, the project documentation shall contain a means of determining andrecording the acceptable tonal range

3.5.4 Acceptable tonal range The acceptable tonal range for the permanent structure shall

be determined from the accepted test panel and the requirements of Clause 3.6.3(b) Where

a tonal scale is used the tonal range of the accepted test panel shall be recorded as set out inClause 5.6.4

Elements of the permanent structure that exhibit a range of tones, when evaluated inaccordance with Clause 5.6.4, which are not outside the range of tones recorded from the testpanel, shall be deemed to comply with Clause 3.5

NO TE: Profile factors may affect measurement of previous tolerances.

TABLE 3.4.3 ACCEPTABLE DEVIATIONS FOR PRECAST CONCRETE UNITS

Tolerance

Acceptable deviation, mm

Dimensions of flat panels Panel length or width

Cross-section overall dimensions

Length, critical dimensions of abutting members 0 6

Length, non critical

Length (mm ) Length (mm )

Features in all units

Diameter or side dimensions of core holes, ducts

Location of grooves and fastenings for window frames, door frames and similar features 3 3 Location of grooves or strips for flashings 6 6 Location of electrical outlets and similar features 12 12 Other requirements As specified* As specified* Irregular curved or unusual shapes As specified* As specified* Position of individual connecting bolts, bolt holes,

projecting metal or other devices in any associated group (e.g the joint of two precast units), with respect to their position in the group 3 3Longitudinal location of any group of bolts, bolt

holes, projecting metal or other devices, with respect of its true position in the unit in which the

Angular

dimensions

Squareness of corners

* As given in the project documentation.

(i) Class 1 or Class 2 untreated surfaces.

(ii) Colour control

(iii) Surface treatment

(c) Exclusion Test panels are not applicable to work having Class 4 or 5 surface finish,and shall not be specified

3.6.2 Details Test panels for precast concrete shall comply with Item (a) below only; forother work they shall comply with either Item (a) or (b):

(a) Separate test panels may be detailed and specified in the project documentation foreach of the three applications set out in Clause 3.6.1(a); alternatively, a single panelmay serve more than one application

(b) If there are no details given in the project documentation, a test panel consistent withthe relevant surface area shall be required for conformity with this Standard Thepanel(s) shall incorporate all relevant features of the surface, e.g the tie rod pattern andtype, joints to adjacent elements, grooves, rebates, openings, and corners and shall beconsistent with the requirements documented for the permanent structure The testpanel(s) shall be reinforced in a manner similar to the permanent work

Where surface treatment is specified an additional test panel of a size appropriate tothe specified surface treatment shall be provided for use in accordance withClause 5.6.2.1(c)

3.6.3 Evaluation Test panels shall comply with the following requirements:

Clause 5.6, shall comply with the requirements of Tables 3.4.1, 3.4.2, and 3.4.3 asapplicable

(b) Colour control The tonal range of the accepted test panel shall be determined by theuse of either the tonal scale or the other means referred to in Clause 3.5.3 If this tonalrange is less than that given in Table 3.6.1 for the surface class specified, then theacceptable tonal range shall be increased to equal at least the number of tones given

in Table 3.6.1

TABLE 3.6.1 TONAL RANGES, GREY SCALE,

APPENDIX B

Class Minimum tonal range

1 2 3

4 tones

5 tones

6 tones

Where the concrete colour is such that the tonal scale is not suitable, then the approvedtest panel shall be permitted to have tonal variations which are consistent with theintent of Table 3.6.1.

NOTE: Due to the large number of factors that affect colour consistency, some colourvariations can always be expected

project documents in accordance with Table 3.4.2 and shall have acceptable surfacedetails and texture

(a) limit state methods (see Clause 4.5.4);

(b) permissible stress methods (see Clause 4.5.5); and

(c) testing (see Clause 4.5.3)

Minimum requirements for the documentation of the formwork design are also provided inClause 4.7

Figure 4.1 sets out, in flow chart form, a guide to the use of this Section

4.2 APPLICATION OF SECTION The loads given in Clause 4.4, as appropriate, shall

be used for formwork design except for the following situations where the requirements ofthis Section may not be sufficient; the loading should then be assessed from the best availableinformation:

(a) Where the formwork assembly is of unusual construction

(b) Where the formwork assembly is subject to unusual loads

(c) Where the formwork assembly is to be used under conditions of loading that are moreadverse than those given in this Section

The technique of formwork fabrication, timing, erection, use and removal can affect thestructural integrity, accuracy, surface finish and long term deformation of both the concreteelements it is used to produce and the previously cast portions of the permanent structure

It is therefore essential that the matters listed in Section 2 be known prior to commencement

of the formwork activity and that, where applicable, they are contained in the formworkdocumentation

This Section does not consider the calculation of eccentricity for struts, or assemblies acting

as struts, where the length exceeds 8 m

4.3 DESIGN REQUIREMENTS

4.3.1 General The design of the formwork shall include consideration, not only of thestructural adequacy, but also of the restraint system to be used, footings, constructiontechniques and, where applicable, surface finish

4.3.2 Structural requirements The structural requirements are as follows:

(a) Stability The formwork assembly shall resist overturning, uplift, sliding and sideswayunder the action of all appropriate load combinations

effects of all appropriate load combinations

(c) Stiffness The stiffness shall be such that the deformation under the appropriate loading

on the formwork assembly and its component members does not exceed the limitsspecified in this Standard

NOTE: Some authorities may require the design to consider other criteria, e.g provisions for safety

4.3.3 Restraint systems The members and connections of bracing systems required toreduce the effective lengths of compression members shall be designed to transfer the forcesand moments specified in Clauses 4.4.6.1 and 4.4.6.2 from the points where the forces ormoments arise to the foundation or to the permanent structure (where this is permitted by theproject documentation (see Clause 2.3(d)).

4.3.4 Construction The detailed design of the formwork assembly shall permit thecomponents to be erected and dismantled without conflict with other structures or the newlypoured structure

4.3.5 Foundations and footings The foundation material beneath the formwork assemblyshall be investigated to determine its bearing and settlement characteristics

A footing system shall be designed to support the formwork assembly on the foundationmaterial so that the whole support system satisfies the requirements for stability, strength andstiffness

4.4 LOADS

4.4.1 General The loads imposed on a formwork assembly and its components shall bedetermined in accordance with Clauses 4.4.2 to 4.4.6, taking into account each of thefollowing stages in the construction cycle:

(i) during handling and erection of the formwork structure; and(ii) once the formwork structure is erected, but prior to placement of concrete

(c) Stage III — after placement of concrete, and until the concrete is able to support the

applied loads

The loads shall be combined in accordance with the requirements set out for the relevantdesign procedure These loads shall take precedence over those defined in the relevantmaterial design standard

(i) Quv= 1.0 kPa; or(ii) Quv= 0 kPa

(i) Quv= 1.0 kPa

(ii) Concentrated live load, taken as a 5 min duration load,

Q c= 3.0 kPa over an area 1.6 m ×1.6 m square at any location and zero overthe remainder

FIGURE 4.1 FLOWCHART FOR SECTION 4

(c) For Stage III Either —

(i) Where there is only one floor level to be supported, either —

(A) Q uv = 1.0 kPa; or(B) Q uv = 0 kPa; or(ii) Where there is more than one floor level to be supported; the topmost level at

1.0 kPa, and the other levels taken at 0.25 kPa (see also Clauses 4.4.2.5 and4.4.4)

4.4.2.4 Load from stacked materials (M) The load from stacked materials which can occur

in any of the three stages, e.g forms, frames, sand, bricks, and reinforcement shall not exceedthat nominated in the project documentation (see also Clause 4.4.4)

The design load for stacked materials shall be as follows:

(a) Stage I M1= 4.0 kPa

(b) Stage II M2= 0 kPa

(c) Stage III M3= 4.0 kPa

Where the construction control is well defined at the time of formwork design and it isclearly advised that there will be adequate control on site to ensure that nominated loads fromstacked materials are not exceeded, then alternative loads which are less than those givenabove may be used Alternative loading values used in the design calculations shall be clearlyindicated in the formwork documentation

Consideration shall also be given to the loads imposed by stacked materials during Stage II

The vertical live load (Quv) is considered to act concurrently with loads from stacked

(a) Where there is a positive system to ensure that the loads on the assembly are

maintained concentric or at a fixed eccentricity (e′) the total eccentricity (e) shall be

taken as follows:

(i) For the design of a strut other than that covered by (a)(ii):

(ii) For sample evaluation on newly-manufactured components or for the testing, in

accordance with Appendix A, of any formwork component or assembly:

(ii) For sample evaluation of newly-manufactured components or for the testing, in

accordance with Appendix A, of any formwork component or assembly:

where

e = the total eccentricity

e′ = the fixed eccentricity

e′′ = an expected eccentricity, which shall be taken as the smallest of —

(A) 0.25 bp;(B) 0.25 times the width of the bearer or beam transferring load to thestrut (see Figure 4.4.1(a)); or

(C) 40 mmwhere

bp = the stiff portion of bearing of an end plate (see Figure 4.4.1(b))

L = the overall length of the strut, or assembly of struts (see Figure

4.4.1(c))NOTE: In the case of vertical struts, this distance will usually be the distancefrom the base plate to the underside of the bearer

The eccentricities calculated in (a) and (b) above are intended to apply to componentstypically encountered in formwork construction Wherever appropriate, larger eccentricitiesshall be used

In some cases the maximum eccentricity may not occur under maximum load Considerationshall therefore be given to the possibility of buckling of a strut during Stage II, before themaximum concrete load is reached

Where appropriate, eccentricity of members in tension shall also be considered

4.4.4 Multistorey loading The number and type of formwork components or assemblies

in use at any particular time of the construction cycle shall comply with the projectdocumentation for the minimum number of levels and type of formwork supports relative tothe anticipated time between construction of subsequent floors and the expected ambienttemperature (see Clause 2.3(c))

Where the lowest set of supports is seated on a rigid foundation the minimum load capacity

of formwork supports (including reshores) shall be not less than that required to support thetotal weight of suspended floor systems, stacked materials, formwork and superimposed loadslocated above the supports

Where the lowest set of supports is seated on a suspended floor structure the minimum loads

on the formwork shall be not less than 2.0 times the heaviest one of the supported floorsabove the lowest set of supports, plus its superimposed loads, i.e

Capacity of supports

(a) by permissible stress:≥ 2(G + G c + Q + M) (see Clause 4.5.5.3)

(b) by limit state: ≥2[1.25(G + G c ) + 1.5(Q + M)] (see Clause 4.5.4.3).

Pmax. = maximum lateral concrete pressure, in kilopascals

ρ = wet density of concrete, in kilograms per cubic metre

C1 = coefficient dependent on the size and shape of formwork

= 1.5 where both plan width and breadth of the section are less than 2 m

= 1.0 for all other cases

R = rate at which the concrete rises vertically up the form, in metres per hour

C2 = coefficient given in Table 4.4.1 for the constituent materials of the concrete

K = temperature coefficient

=

H = vertical form or concrete discharge height, whichever is the greater, in metres

h = vertical pour height, in metres

T = concrete temperature at placement, in degrees Celsius

Where C1√R > H, or where R or H are not known, Equation (b) above shall be used.

These equations are not suitable for use in the following cases:

(a) Grout injected concrete, or where the concrete is pumped from below into the forms(see Figure 4.4.2)

(b) Deep re-vibration of the concrete

(c) External vibration

NOTES:

1 The above equations were obtained from CIRIA Report No 108

2 The equation is conservative for no-fines concrete, underwater concreting and verypermeable forms such as expanded metal

3 The equation has not been proven for temperatures in excess of 30°C or below 5°C

4.4.5.2 Horizontal load due to sloping formwork Account shall be taken of the horizontalloads arising from vertical loads including dead, live and concrete loads, imposed uponsloping formwork

4.4.5.3 Horizontal live loads (Q uh , I) The following horizontal live loads shall be takeninto account:

(a) Horizontal live load (Q uh ) The horizontal live load Quh due to any of the followingshall be determined for the structure:

(i) Forces in concrete pumping systems

(ii) Braking of trolleys, skips or other vehicles

(iii) Cable tensions

(iv) Action of workers and equipment

Under no circumstances shall the sum of horizontal live loads be less than 1 kN/m of formedge with a minimum of 5 kN

AS 1657 This load shall be considered as part of the 1 kN per metre load in (a) aboveand shall not be cumulative

completed formwork assembly it shall be designed to sustain a horizontal force (I).

Unless the direction of the force is known it shall be considered to act in any direction

in the horizontal plane and shall be assumed not to act concurrently with the horizontalforces determined in (a) or (b) above Partial collapse, damage and deformation ordeformation, alone from this force is acceptable It shall not result in progressivecollapse

4.4.5.4 Wind loads (W p and W u ) Wind loads shall be as set out in AS 1170.2 Wp is for

use with permissible stress design procedures and is derived from Vpin AS 1170.2 Wuis for

use with limit state design procedures and is derived from Vuin AS 1170.2

NOTE: Wind loads may be assumed not to act during Stage II except in the unusual situation wherethe combination of dead, live and wind loads could be more critical than in Stages I or III

4.4.5.5 Loads due to water (X w ) Where applicable, the forces due to the action of any ofthe following shall be taken into account:

(a) River currents

(b) Tides

(c) Wave action

(d) Flooding

NOTE: Some guidance in respect to these loads may be obtained from BS 5975

4.4.5.6 Earthquake loads Where formwork remains in place for more than 6 months,

TABLE 4.4.1 VALUES OF COEFFICIENT C 2

Cementitious materials and admixtures C 2

Type GP, HE cement Type LH, SR, SL cement Type GB cement Blends containing > 40% flyash or > 70% slag

0.30 0.45 0.45 0.60 For all cementitious types the value of C2shall be increased by 0.15 where one or both of the following apply:

(a) A retarding admixture is used in the concrete.

(b) A superplasticizing admixture is used in the concrete.

NO TES:

1 Retarding admixtures include retarders, retarding water reducers, retarding superplasticizers and any admixture which is used such that it effectively acts as a retarder.

2 Products which have become commercially available since the publication of CIRIA Report 108 in 1985 should be investigated to determine whether they should be classified as retarders.

3 This Table is based on CIRIA Report 108 and the appropriate types

of cement given in AS 3972 have been substituted for those tested.

Note that in AS 3972, Type SR cement is defined on a performance basis and may contain a high percentage of slag necessitating the use of a higher value of coefficient C2.

4 Silica fume has a marked effect on the properties of fresh concrete and is frequently used in conjunction with superplasticizers.

Concrete with this ingredient falls outside the test parameters of the CIRIA Report and no guidance can be provided.

4.4.5.7 Other horizontal loads Where additional loads such as those from otherconstruction activities occurring concurrently with formwork construction are likely to imposehorizontal forces on the formwork assembly, these shall be taken into account (also seeClause 4.4.6)

4.4.6 Loads applicable to components that provide buckling restraint

4.4.6.1 General For any formwork component or assembly used to reduce the effective

length of a compression member, a load HLshall be taken into account in the design of thatformwork component or assembly in accordance with Clause 4.4.6.2 or Clause 4.4.6.3 asappropriate

4.4.6.2 Where restraint is provided to a single compression member Where restraint isprovided to a single compression member —

(a) it shall be assumed to act in any direction at right angles to the axis of the compressionmember;

(b) its value shall be calculated by the following equation:

where

HL = the load applicable to the component that provides the buckling restraint

Pv = the axial force in the compression member at the location of the restraint;and

(c) it shall be assumed to act in addition to other loads

4.4.6.3 Where restraint is provided to more than one compression member In addition tothe load calculated in Clause 4.4.6.2, an additional load equal to half that value for eachadditional compression member being restrained, up to a maximum of seven members.

4.4.7 Use of permanent structure as restraint The permanent structure shall not be used

as restraint for formwork unless permitted in the project documentation (see Clause 2.3(d))

4.5 ANALYSIS AND DESIGN

4.5.1 General Formwork components or assemblies shall be analysed and designed inaccordance with Clause 4.5.2 or tested in accordance with Clause 4.5.3 Design informationshall be provided in accordance with Clause 4.5.6 and formwork documentation shall be inaccordance with Clause 4.7

For all members or assemblies loaded in compression, eccentricity shall be taken into account

in accordance with Clause 4.4.3

Where differences exist between requirements of the material design standards and thisStandard, the requirements of this Standard shall take precedence

Where the whole formwork assembly is composed of members of different materials, acombination of the methods described in Clause 4.5.2(a) and (b) may be used

4.5.2 Theoretical analysis Formwork components or assemblies shall be analysed anddesigned in accordance with one of the following procedures:

(a) Limit state procedures, in accordance with the appropriate material structural designcode and Clause 4.5.4

(b) Permissible stress procedures, in accordance with the appropriate material structuraldesign code and Clause 4.5.5

4.5.3 Testing Determining and proving the structural capacity of formwork componentsand assemblies shall be either by destructive or non-destructive evaluation Interpretation ofresults from testing, presentation of design data and use of this data shall be in accordancewith Appendix A

4.5.4 Limit state design procedures

4.5.4.1 Load combinations for limit-state approach Loads shall be multiplied by theappropriate factor and added to give a ‘limit state’ load as indicated in the equations given

in Table 4.5.1 Where there is choice of load direction or magnitude for the specified loads,the most adverse combination shall be selected Where live loads and loads from stackedmaterials occur, both the full and zero values of these loads shall be considered to determinethe most severe condition

NOTE: The general equation for load combinations in Table 4.5.1 takes the following form:

Limit state load, S* = (load × load factor)

e.g Equation 4 of Table 4.5.1: S* = 0.8G + 1.1I.

4.5.4.2 Stability limit states The formwork assembly shall resist overturning, uplift, slidingand sidesway under the action of the most adverse load combination specified inClause 4.5.4.1

4.5.4.3 Strength limit states The formwork assembly and its component members shallsatisfy the following equation:

φRu≥ S*

φ = strength reduction factor given in the appropriate material structural

design code for the particular type of action effect

Ru = design ultimate strength of the material or assembly determined in

accordance with Clause 4.5.4.1, or by testing in accordance withClause 4.5.3

S* = design action effect due to the most adverse limit state design load

determined in accordance with Clause 4.5.4.1

4.5.4.4 Stiffness limit state The formwork assembly and its component parts shall satisfythe following requirements:

tolerances given in Clause 3.4.3 are not exceeded when the load combinations forstiffness set out in Table 4.5.1 are applied

(b) Vibration The formwork shall be designed and constructed to have sufficient stiffness,mass, or both, to avoid any detrimental effect of vibration on its structural capacity,tolerances, surface finish and safety

4.5.5 Permissible stress design procedures

4.5.5.1 Load combinations for permissible stress approach Loads shall be added and thetotal multiplied by the appropriate reduction factor to give a ‘permissible stress’ design load,

as indicated in the equations given in Table 4.5.2 Where there is a choice of load direction

or magnitude for the specified loads, the most adverse combination shall be selected.NOTE: The general equation for load combinations in Table 4.5.2 takes the following form:

where Fps= the permissible stress load:

Fps= (Load 1 + Load 2 + )× Combined reduction factor

e.g Equation 8 of Table 4.5.2:

Fps= (G + Gc + Quv+ M2+ I) × 0.67

4.5.5.2 Stability The formwork assembly shall resist overturning, uplift, sliding andsidesway under the action of —

(a) 0.8 times the whole of the dead load tending to prevent overturning;

(b) 1.25 times the dead load, if any, tending to cause overturning; and

(c) 1.5 times the static load equivalent of other loads tending to cause overturning.NOTE: Larger factors may be needed in special formwork applications

4.5.5.3 Strength The formwork assembly and its component members shall satisfy thefollowing equation:

where

F′ps = load-carrying capacity of the formwork structure or component

Where the component is a proprietary item, this information is provided

by the manufacturer of the item and is usually called ‘working load’ Forstructures or components other than proprietary items, the load carryingcapacity is obtained from the appropriate material design Standard

Fps = the most adverse ‘permissible stress’ design load calculated in accordance

with Clause 4.5.5.1