IS 6461 (Part 5) — Formwork for Concrete · Concrete Glossary

Accessories Cl 3.1

Items other than frames, braces, o r post shores used to facilitate the construction of scaffold and shoring.

Access Door (Inspection Door or Porthole or Trap Door) Cl 3.2

A removable panel in the formwork for a high lift to give access for inspection or for placing or compacting concrete (see also 3.67).

Activating Agent Cl 3.4

See 3.309.

Adjustable Prop, Telescopic Prop Cl 3.5

A prop whose length may be varied.

Adjuster Cl 3.6

A mechanical device for bringing formwork to its correct line or level or both.

Anchor Cl 3.7

A device for providing a fixing to a concrete surface (see also 3.141).

Anchor Bolt Cl 3.8

A bolt passing through the member to be anchored and engaging with the anchor.

Anchor Plate Cl 3.9

A plate on the embedded end of an anchor which increases its resistance to being pulled out of the concrete.

Anchor Slot Cl 3.10

See 3.106.

Angle Fillet Cl 3.11

A strip used to form an internal or external intersection which is to be other than a sharp angle.

Apartment Formwork Cl 3.12

Room formwork for casting a concrete slab and its supporting walls in one continuous operation.

Arris Cl 3.13

Sharp edge or protruding corner formed by meeting of two surfaces, whether plane or curved, applied especially to edges in mouldings and edges separating fluting.

Back Propping Cl 3.15

Propping to cast concrete floors which allows them to support formwork for higher floors.

Ballies Cl 3.16

Thin poles in the round shape usually without bark.

Barrier Paint Cl 3.17

See 3.266.

Bar Spacer Cl 3.18

A device for maintaining reinforcement in its correct position within the formwork (see also 3.90).

Batter Cl 3.20

A small inclination from the vertical.

Batter Boards Cl 3.21

Pair s of horizontal boards nailed to wood stakes adjoining an excavation, used as a guide to elevations and to outline the building.

Bay Cl 3.22

An area of concrete bounded by construction joints, expansion joints or free edges.

Beam Box Cl 3.23

The assembled side and bottom formwork for a beam.

Beam Clamp (Clamp or Cramp) Cl 3.25

A yoke or other device, which holds a beam box tightly against the pressure of freshly placed concrete.

Beam Side Cl 3.28

Vertical side panels or parts of a beam form.

Bearing Cl 3.29

A surface which transmits direct compressive load from one member to another.

Bearing Area Cl 3.30

The area of the interface over which bearing stress exists.

Bearing Length Cl 3.31

That length of beam which rests on a support.

Bearing Stress Cl 3.32

T he compressive stress which exists at the interface between two structural members where the forces exerted by one member on the other tend to crush the materials of which the members are made.

Bent Cl 3.33

A two-dimensional frame used as a supporting structure, usually when a number of such frames are used as the supports of a long narrow structure, such as a jetty or pier.

Bevel Cl 3.34

The intersection of one plane surface with another plane surface at an angle other than a right angle.

Bevel, To Cl 3.35

To cut the edge of a panel or board at an angle other than a right angle.

Note — This is normally done so that the panels or boards may easily be struck or to form an intersection between two such panels w boards.

Binding Cl 3.36

The adherence of forms to the co ncrete when the supports are removed and striking is attempted.

Block Cl 3.38

A piece of wood or other material used to pack out or separate, or; when glued, to stiffen other members (see also 3.206).

Blowhole Cl 3.40

A small hole, generally smaller th an about 16 mm across in a concrete face, caused by an air pocket.

Blow Out Cl 3.41

To use compressed air for clea ning out the inside of formwork before concreting.

Board a) A piece of square Cl 3.42

sawn softwood/timber under 50 mm thick and 100 mm over wide; b) A piece of square-sawn or unedged hardwood timber 50 mm or less in thickness and of the required width; and c) Manufactured rigid or semi-rigid sheets, such as laminated board, wood chipboard and other particle board or hard-board.

Bolt Sleeve Cl 3.43

A cylindrical or other shaped form thro ugh which a bolt passes so as to separate the bolt fro m the surrounding concrete.

Box Cl 3.44

Formwork for a beam or column (see also 3.23, 3.45 and 3.73).

Box Cl 3.45

Out — The form for a pocket or aperture in concrete.

Bracing Cl 3.47

The system of members, usually diagonal, which acts in compression or tension and stiffens a frame against deformation.

Break Down Cl 3.48

To dismantle made -up formwork after it has been struck.

Brick Seat Cl 3.49

Ledge on wall or footing to support a course of masonry.

Building Board Cl 3.50

A loose term applied to most boards.

Bulkhead Cl 3.51

A vertical partition within the forms, blocking fresh concrete from a section of forms or closing the end of a form, such as at a construction joint.

Butt Joint Cl 3.52

A plain sq uare joint between two members.

Camber Cl 3.53

The intentional curvature of a beam or formwork, either formed initially to compensate for subsequent deflection under load or produced as a permanent effect for aesthetic reasons.

Cantilever Formwork Cl 3.54

Formwork which is supported solely by members fixed to, and projecting beyond, previously hardened concrete.

Carcassing Timber ( Framing Timber ) Cl 3.55

Timber used for any structural purpose in the support of the forms, but not normally in contact with the concrete.

Cast Cl 3.56

in-Socket — An anchor consisting of a female-threaded metal socket cast into concrete as a fixing for a bolt.

Centre Cl 3.58

See 3.136.

Chase Cl 3.60

A long groove or recess formed in the concrete surface.

Chase Form Cl 3.61

A form for moulding a chase. It is often a wooden moulding planted on the face of the main form (see also 3.63).

Check Cl 3.62

A small strip of timber fixed to the face of a form to indicate the top of a concrete lift and to form a clean line at the joint with the next lift (see also 3.158).

Check Out Cl 3.63

A piece of wood or other material fixed to the face of a form to farm a recess in concrete (see also 3.61).

Chipboard Cl 3.64

See 3.350.

Clamp Cl 3.65

See 3.25, 3.75 and 3.344.

Cleanout Trap Cl 3.67

A removable section at the base of the forms for a column or wall which allows rubbish to be removed before concreting (see also 3.2).

Climbing Formwork (Moving Formwork) Cl 3.69

Formwork for vertical or near vertical structures which are constructed in successive lifts and which is supported by the previously poured lift ( see also 3.190).

Coffer Form Cl 3.70

See 3.340.

Coffered Slab Cl 3.71

See 3.343.

Collapsible Forms Cl 3.72

Forms which are activated by mechanical means to reduce their volume or surface area to permit striking.

Column Box Cl 3.73

The assembled forms for a column.

Column Casing Cl 3.74

See 3.73. IS 6461 (Part 5) : 2024 3

Column Clamp Cl 3.75

A yoke or other device which holds a column box tightly closed against the pressure of freshly placed concrete.

Column Guard Cl 3.77

A length of metal angle cast into a corner of a column to protect it against d amage.

Column Side Cl 3.78

One of the vertical panel components of a column form.

Cone Cl 3.79

A cone-shaped piece of wood, rubber or other material which is placed over the end of a form tie to form a neat hole in the surface of the concrete.

Construction Joint Cl 3.80

The interface between adjacent concrete pours which are designed to act monolithically in the completed structure (see also 3.94).

Continuously Sliding Form Cl 3.81

See 3.278.

Contraction Joint Cl 3.82

See 3.272.

Control Joint Cl 3.83

Groove (formed, saw cut or tooled) in concrete structure to regulate the location of shrinkage cracks.

Corbel Cl 3.84

A projection/flaring from the face of a wall or column, usually to provide a bearing for a beam.

Counter Cl 3.87

Waling — See 3.303.

Cove Cl 3.88

An infill which produces a concave curve connecting the two surfaces forming an internal angle such as that between a wall and a ceiling or floor.

Cover (Reinforced Concrete) Cl 3.89

T he least d istance between the surface of the reinforcement and the face of the concrete.

Cover Block Cl 3.90

A device which is fixed between reinforcement and the face of a form to ensure correct cover to the reinforcement.

Cradling Cl 3.91

Light timber framing in formwork.

Cross Brace Cl 3.92

A pair of diagonal braces.

Crown Centre Cl 3.93

In centering, a structure which supports ribs at the crown of a dome.

Day Joint Cl 3.94

A construction joint formed at the end of a day’s concreting.

Dead Load Cl 3.95

The self-weight of the forms and the permanent structure supported by them (see also 3.196).

Dead Man Cl 3.96

A heavy block or beam, sometimes buried, used to anchor a guy or form tie.

Dead Shore Cl 3.97

A support to hardening concrete designed to be left in place when the soffit form is struck.

Deal Cl 3.98

A piece of square-sawn softwood timber 50 mm to 100 mm thick and 230 mm to 280 mm wide.

Deflection Cl 3.100

The deformation of a member caused by bending stress.

Delamination Cl 3.101

The separation of the layers which make up plywood or laminated wood.

Deviation Cl 3.102

The distance between the actual position of a reference joint and its specified position ( see also 3.325).

Distance Piece Cl 3.103

A short piece of timber or other material used to hold parallel forms for walls or beams at the correct spacing.

Domed Pan Cl 3.104

See 3.340 .

Double Cl 3.105

Headed Nail — A round-wire nail which has a second head formed in the shank, just below the head struck by the hammer.

Note — After being driven home this nail leaves a projecting head for easy withdrawal.

Dovetailed Anchor Cl 3.106

A device made from sheet steel or other metal and cast into the concrete surface to produce a chase which is narrower at the surface than at its base into which IS 6461 (Part 5) : 2024 4 shaped metal tongues are inserted to form an anchor.

Dowel Cl 3.107

A cylindrical piece of wood used for positioning and fixing one member to another.

Dowel Bar Cl 3.108

A short metal rod or bar cast into concrete with part of its length left projecting as a fixing or (especially in road and other slabs) as a means of transferring forces acting in the plane of a joint from one member or slab to another.

Note — One end of a dowel is usually fixed in one member while the other end is free to slide in the other member. Forces may thus be transmitted across the axis of the dowel but not along it.

Dowel Pin Cl 3.109

See 3.108.

Drawform Cl 3.110

A loose vertical metal plate which separates an integral facing from the backing concrete and which is gradually withdrawn as the form is filled to allow the two mixes to bond together.

Dressed Timber Cl 3.111

See 3.218.

Drip Cl 3.112

A cut out in the underside of a projecting piece of wood, stone or concrete to prevent water from working its way back to the wall.

Dummy Joint Cl 3.113

A groove in the surface of the concrete which gives the appearance of a joint.

Easing Wedges Cl 3.114

See 3.139.

Edge Form Cl 3.115

The formwork to the edge of a road or other slab.

End Lug Cl 3.116

An end bearing plate on floor centres.

Note — An end lug is sometimes adjustable.

Expanded Metal Cl 3.117

A metal network or mesh formed by suitably stamping or cutting slits in sheet metal and stretching it to form open meshes, usually of diamond shape.

Note — Expanded metal may be used as reinforcement in concrete and for forming box-outs and stop ends.

Expanded Polystyrene Cl 3.118

A rigid plastics material, usually in the form of sheets or blocks, which is made by pressing together particles of polystyrene which have been expanded by steam to form non-porous, ultra-lightweight beads (see also 3.247).

Note — Expanded polystyrene is used to form box outs and other awkward shapes in concrete.

Exterior Plywood Cl 3.119

Plywood normally bonded with a phenolic resin adhesive, which complies with the ‘ weather and boil proof (WBP)’ requirements.

External Vibrator Cl 3.120

A vibrator which is attached or applied to the outside of the forms.

Face Mix Cl 3.121

See 3.176.

Fair Face Cl 3.122

A plain concrete finish better than that produced from rough formwork.

Fascia Cl 3.124

A flat member or bend at the surface of a building or the edge beam on a bridge or exposed eave of a building, etc.

Feather Edge Cl 3.125

The sharp edge produced when two surfaces meet at an acute angle.

Fibre Glass Cl 3.126

A mat or cloth made from strands of glass.

Note — Glass fibre is used in glass fibre reinforced plastics in the construction of moulds and forms.

Fibre Glass Reinforced Plastic Cl 3.127

A material made from plast ics or resins reinforced by glass fibre, usually by building up successive layers of these component materials.

Filler Cl 3.128

See 3.294.

Fillet Cl 3.129

A piece of timber, of triangular cross-section, fixed at the intersection of two forms to produce a chamfer on the concrete.

Film Overlay Plywood Cl 3.130

Ply wood to the faces of which a layer of resin in the form of a sheet (or film) is permanently bonded during manufacture, usually by means of heat and pressure, so as to form a smooth no n-absorbent surface (see also 3.221).

Fin Cl 3.131

An undesirable projection from the face of the concrete caused by grout escaping into a gyp along a joint in the form.

Fishplate Cl 3.132

A plate used for connecting the webs of members where these are to be joined end to end. IS 6461 (Part 5) : 2024 5

Flat Jack Cl 3.133

A jack, made of two dished steel sheets with one inverted onto the other and the two welded together round their rims, which is inflated by injection of oil or grout under pressure.

Flexible Foamed Polyurethane Cl 3.134

Polyurethane which has been expanded during manufacture to form a flexible multi -cellular material.

Note — Flexible foamed polyurethane is mainly used in formwork by being compressed in the joints between boards and between forma and the concrete to prevent grout loss.

Flier Cl 3.135

See 3.137.

Floor Centre Cl 3.136

A beam of adjustable length, usually a metal -lattice or sheet -metal box beam, used to support decking for a floor slab.

Flying Shore Cl 3.137

A horizontal strut fixed above ground between two walls.

Foamed Polystyrene Cl 3.138

See 3.118.

Folding Wedges Cl 3.139

Wedges, usually timber but occasionally metal, used in pairs for levelling and adjusting formwork during erection and/or to release loads on formwork prior to striking. They are also used to tighten or slacken connections between formwork members (see also 3.334).

Form Anchor Cl 3.141

A device used in the s ecuring of formwork to previously placed concrete of adequate strength. The device is normal ly embedded in the concrete during placement.

Form Coating Cl 3.142

See 3.266.

Form Hanger Cl 3.143

See 3.27(b).

Form Lining Cl 3.144

Prepared timber, board or sheets of plastics, paper or other material, fixed to the inside face of the form to produce a special surface finish.

Form Plucking Cl 3.145

Removal of the surface of the form due to adhesion of the form to the concrete.

Form Scabbing Cl 3.146

See 3.145.

Formwork Cl 3.148

Complete system of temporary structure built to contain fresh concrete to form it to the required shape and dimensions and to support it until it hardens sufficiently to become self supporting. Formwork includes the surface in contact with the concrete and all necessary supporting structure (see also 3.200).

Gang Mould Cl 3.150

A series of moulds so arranged that many identical precast units can be formed on the same base.

Ganged F orm Cl 3.151

A number of panels fixed together and stiffened with walings, strongbacks or soldiers, or combinations of these.

Gill Cl 3.152

See 3.276.

Grain (of Wood) Cl 3.153

The general direction or arrangement of the fibres, like spiral grain, straight grain, etc.

Grillage Cl 3.154

An assemblage of timber or steel members placed parallel to each other under a sill to spread the load from the sill.

Note — Where the load is large, a grillage may consist of two or more layers of parallel members is placed across each other at right angles.

Grit Blasting Cl 3.155

The abrasion of a surface by blowing grit on to it at high velocity (see also 3.271).

Note — Grit blasting is sometimes used to accentuate the g rain of timber for greater effect in roughboard formwork.

Groundcill Cl 3.156

A cill which is in direct contact with the ground.

Grout Loss Cl 3.157

The loss of cement and water from fresh concrete by leakage through joints in the forms.

Grout Seal Cl 3.158

Material or method used for s ealing joints in forms to prevent grout loss. Normally, a strip of compressible material inserted in the joints. IS 6461 (Part 5) : 2024 6

Grout Strip Cl 3.159

A batten fixed to a form to create a clean line at the top of a concrete lift.

Note — The clean line so produced allows even contact of the forms for the next lift and helps minimize grout loss.

Gusset Cl 3.160

A plate made of steel, timber, plywood or other material which is nailed or bolted over main timbers to form or strengthen a joint between them.

Guy Cl 3.161

A rope fixed at one end to a s tructure, and at the other end to a stake, dead man or other secure point in order to provide resistance to lateral forces.

Guy Rope Cl 3.162

See 3.161.

Hanger Cl 3.163

A vertical member giving support from above (see also 3.27).

Hanging Formwork Cl 3.164

Formwork which is supported from above (see also 3.27).

Hardboard Cl 3.165

Fibre building board having a nominal thickness of 3 mm to 12 mm, usually made from wood fibres.

Hollow Form Cl 3.167

A form for producing weight-reducing recesses in the soffit of a suspended slab (see also 3.335, 3.341 and 3.342).

Hollow Mould Cl 3.168

See 3.167.

Hydrostatic Pressure Cl 3.169

The pressure exerted on the formwork by the freshly placed concrete where this is effectively a fluid.

Immersion Vibrator Cl 3.170

A vibrator which is inserted into the freshly placed concrete (see also 3.225).

Inflatable Form Cl 3.172

A form which acquires the required shape by internal pressure and which is deflated for striking. It is usually long relative to its cross-sectional dimensions.

Insert Cl 3.173

A piece of timber or other material cast into the concrete surface usually to provide a fixing.

Insulation Cl 3.175

A cover of insulating material intended to reduce loss of heat. It is used on forms in cold water to reduce loss of heat from the concrete.

Integral Facing Cl 3.176

A special facing concrete or mortar, cast simultaneously with the backing concrete so as to be monolithic with it. It is often cast by using a drawform.

Internal Vibrator Cl 3.177

See 3.170.

Jack Cl 3.178

A mechanical device for raising heavy loads (see also 3.133).

Jack Rod Cl 3.179

A steel rod upon which jacks act in order to raise slip forms.

Joist Cl 3.180

A horizontal or sloping beam, in particular the horizontal timbers which carry decking for a suspended concrete slab.

Kerf Cl 3.181

A saw cut which is not the full depth of the timber.

Kerfing Cl 3.182

See 3.256.

Kerf Cl 3.183

Sawing — See 3.256.

Key Cl 3.184

The treatment of a concrete surface to ensure the bonding of fresh concrete to that already cast.

Lacing Cl 3.185

Horizontal members which hold together and position props or other vertical supports.

Lagging Cl 3.186

Narrow timbers fixed to a shaped frame for forming curved surfaces.

Laminated Wood Cl 3.187

An assembled product made up of laye rs of wood and adhesives in whic h the grain of adjacent layers is parallel.

Lamination Cl 3.188

One of the individual layers of wood used to make up laminated wood.

Lap Cl 3.189

The part of the length or height of a form which covers the previously placed concrete when the form is fixed in place for the next lift.

Leapfrog Form Cl 3.190

A form for a method of casting vertical surfaces in which two or more sets of forms are used so that the form for the last poured lift may be left fixed in place while that from a lower lift is struck and re-erected on top of it, the process being repeated, if necessary. IS 6461 (Part 5) : 2024 7

Ledge Cl 3.191

A member nailed across a number of boards to hold them together.

Lift Cl 3.193

That height of conc rete which is poured in one continuous operation.

Lining Cl 3.194

See 3.144.

Lip End Cl 3.195

See 3.116.

Live Load Cl 3.196

The temporary forces applied to formwork by the weights of men and construction equipment (see also 3.95).

Lost Formwork Cl 3.197

Formwork that cannot be removed easily and is therefore left in place.

Loose Tongue Cl 3.198

A strip of wood which is inserted into grooves in the edges of adjacent boards where these are to be joined edge to edge (see also 3.326).

Make Cl 3.199

Up Piece — A piece of material used to obtain dimensions greater than those obtainable by use of standard pans or panels.

Mobile Form Cl 3.200

See 3.332.

Moisture Movement Cl 3.201

The swelling and shrinkage of a material caused by varying moisture content.

Mould Cl 3.202

A form for casting precast concrete units.

Mould Oil Cl 3.203

Oil or emulsion applied to the face of forms, its primary purpose being to act as a release agent.

Moving Formwork Cl 3.204

See 3.69, 3.278 and 3.332.

Nib Cl 3.205

A small concrete upstand cast above floor level to position wall or column forms for the next lift and to assist the prevention of grout loss.

Nogging Piece Cl 3.206

A short wooden strut fixed between and at right angles to cleats, joists, studs, walings, etc in order to stiffen them (see also 3.38).

Overlay Plywood Cl 3.207

See 3.130.

Pallet Cl 3.208

A flat timber or metal plate on which precast concrete units are cast and handled until they have hardened.

Pan Cl 3.209

A form of stiffened steel sheet which is a component of a system of formwork. A number of pans may be fixed together to construct a larger area.

Panel Cl 3.210

A prefabricated form of limited size, designed for repeated (use, a number of which may be fixed together to form a larger surface (see also 3.151).

Particle Board Cl 3.211

Board made from particles of wood and/or other lignocellulosic material bonded with synthetic resin and/or other organic binder.

Parting Compound Cl 3.212

See 3.241.

Pencil Round Cl 3.213

T he junction of two concrete surfaces which is finished with a small radius.

Permanent Form Cl 3.214

Forms permanently left in place to provide a facing to the concrete.

Permanent Shutter Cl 3.216

See 3.214.

Placing Rate Cl 3.217

T he rate at which the free surface of the concrete rises in the forms during placing.

Planed Timber Cl 3.218

Timber made smooth on one or more surfaces by planning (see also 3.257).

Plank a) Plank of softwood Cl 3.219

A piece of square- sawn timber 35 mm to 50 mm thick and 230 mm or over wide. IS 6461 (Part 5) : 2024 8 b) Plank of hardwood — A piece of square- sawn or unedged timber over 50 mm thick. The width varies according to the grade and country of origin.

Plaster Mould Cl 3.220

A mould made from plaster.

Plastic Faced Plywood Cl 3.221

Plywood, one or both faces of which have been coated with plastic material or resin which acts as a sealant (see also 3.130).

Plucking Cl 3.222

Spalling of the concrete face due to adhesion of concrete to the form (see also 3.145).

Plywood Cl 3.223

A product of balanced construction made up of plies assembled by gluing, the chief characteristic being the crossing of alternate plies to improve the strength properties and minimize movement in the plane of the board (see also 3.130 and 3.221).

Pocket Cl 3.224

A recess formed in a concrete surface.

Poker Vibrator Cl 3.225

An immersion vibrator consisting of a vibrating tubular head connected to a source of energy.

Polystyrene Cl 3.226

A transparent, hard plastic material.

Polyurethane Cl 3.227

An organic plastic material (see also 3.134, 3.228 and 3.247).

Polyurethane Varnish Cl 3.228

Polyurethane in liquid form which is applied to forms to act as a sealant.

Post Cl 3.230

A vertical support.

Precast Concrete Cl 3.231

Concrete which is cast in moulds before being placed in position.

Profile Cl 3.232

See 3.318(a).

Profiled Form Cl 3.233

A form for casting a concrete surface which is curved or unusual in shape.

Profiled Shutter Cl 3.234

See 3.233.

Prop Cl 3.235

A strut which is light enough to be man-handled.

Note — The term ‘prop’ is commonly used to describe a strut of proprietary manufacture which is adjustable in length.

Pun Cl 3.236

To compact fresh concrete by ramming by hand with a timber or steel rod.

Raker Cl 3.237

See 3.238.

Random Board Forms Cl 3.239

A form, the sheeting of which is made with softwood boards of random widths or lengths or both.

Rebate Check Cl 3.240

A grout which also forms a rebate in the concrete.

Release Agent Cl 3.241

A substance, usually applied to the form face, to prevent adhesion of the concrete to the form and thus facilitate stripping.

Re Cl 3.242

Propping — The application of posts or props to the soffit of a concrete slab or beam to enable it to carry an excess superimposed load, or to carry superimposed loads when the concrete is not fully mature (see also 3.15).

Re Cl 3.243

Shoring — See 3.242.

Resin Bonded Plywood Cl 3.244

Plywood which has been manufactured using a phenolic or other resin as an adhesive (see also 3.119).

Note — Resin-bonded plywood is not necessarily of su fficient quality for use formwork.

Retractable Form Cl 3.245

See 3.314.

Ribbon Cl 3.246

A r unner connecting beam bottom support members to prevent spreading of the lower edges of the side of a beam box.

Rigid Foamed Polyurethane Cl 3.247

Polyurethane which has been expanded during manufacture to form a rigid multi-cellular material. NO TE — Rigid foamed polyurethane is used in formwork for the same purposes cu expanded polystyrene.

Rip Cl 3.248

To cut a timber parallel with the grain.

Riser Board Cl 3.249

The board which forms the vertical face of a step.

Road Form Cl 3.250

An edge form used in the IS 6461 (Part 5) : 2024 9

Raking Strut Cl 3.238

An inclined strut. construction of a road or other ground slab.

Note — The term is normally used to describe specially designed proprietary steel products.

Rough Formwork Cl 3.251

Formwork for concrete where no special surface finish is required.

Roughboard Formwork Cl 3.252

Formwork, the face of which consists of softwood boards with a rough grain or sawn texture so that a similar texture is imparted to the concrete surface.

Runner Cl 3.253

See 3.192.

Sand Box Cl 3.254

See 3.255.

Sand Jack Cl 3.255

A box containing dry sand on which rests the lower end of a vertical strut. On removal of a plug in the side of the box, the sand flows out and the strut is lowered.

Saw Cl 3.256

Kerfing — Parallel kerfs cut on one side of a piece of timber so that it may be more easily bent towards that side.

Sawn Timber Cl 3.257

Timber which has not been planed on any surface (see also 3.218 ).

Sawnboard Formwork Cl 3.258

See 3.252.

Scabbing Cl 3.259

See 3.222.

Scaffold Cl 3.260

A temporary structure for gaining access to higher levels of the permanent structure during construction.

Scaffold Board Cl 3.261

A softwood board used with similar boards to form walkways and as toeboards on a scaffold.

Scaffolding Cl 3.262

See 3.260.

Screed Cl 3.263

See 3.264.

Screed Board Cl 3.264

A templet for the finishing of a concrete surface (see also 3.312).

Screed Rail Cl 3.265

A guide fixed at the perimeter of a concrete pour to act as a datum and support for a screed board.

Separator Plate Cl 3.267

See 3.110.

Sheathing Cl 3.268

See 3.269.

Sheeting Cl 3.269

That part of the form which is in contact with the concrete.

Shore Cl 3.270

See 3.97 and 3.137.

Shot Blasting Cl 3.271

The abrasion of a surface by blowing metal shot on to it at high velocity (see also 3.154).

Note — Shot blasting is sometimes used to accentuate the grain of timber for greater effect in roughboard formwork.

Shrinkage Joint Cl 3.272

A break in the continuity of a concrete structure provided so that shrinkage of the concrete will open this rather than cause cracking of the structure.

Shutter Cl 3.273

See 3.140.

Shuttering Cl 3.274

See 3.148.

Side Form Cl 3.275

A form for the side of a concrete member where the height of the member is not great in proportion to the width of its cross-section.

Sill Cl 3.276

A horizontal timber under the foot of a jack or post used to spread the load from the member above.

Sliding Formwork Cl 3.277

See 3.278.

Slip Form ( Moving Formwork, or Sliding Formwork) Cl 3.278

A form which moves, usually continuously, during placing of the concrete. Movement may be either horizontal or vertical.

Slip Form Paver Cl 3.279

A travelling machine, for laying concrete paving, which carries its own edge forms between which the concrete is compacted.

Slot Anchor Cl 3.280

See 3.106. IS 6461 (Part 5) : 2024 10

Snap Tie Cl 3.281

A form tie designed to be broken off beneath the concrete surface after use.

Soffit Cl 3.282

The under surface of concrete, for example, of a concrete arch, or suspended beam or slab.

Soffit Form Cl 3.283

The form to a soffit.

Soldier Cl 3.284

A vertical member, acting as a beam or cantilever, and used in conjunction with form ties or struts to support and prevent movement of forms.

Sole Plate Cl 3.285

See 3.276.

Spacer Cl 3.286

See 3.103.

Spanish Windlass Cl 3.287

A device for drawing two members together against an outward force. It consists of a number of wires from one member to the other between which a bar is inserted and turned to create a tension in the wires by twisting them together.

Splay Cl 3.288

A concrete mass of triangular cross- section across an internal angle.

Spreader Cl 3.289

See 3.103.

Square Cl 3.290

Edged Boards — Boards of rectangular cross -section with plain edges suitable for butt jointing.

Starter Frame Cl 3.291

Shallow formwork projecting above floor level for the construction of a nib, that is, the formwork for a nib.

Stave Cl 3.292

One of a number of vertical members forming a surface which is curved on plan (see also 3.186).

Stop End Cl 3.293

The form for a construction joint in the vertical plane.

Stopping Cl 3.294

Materials used for filling screw holes, joints, etc, to form a smooth, even surface.

Strap Cl 3.295

A timber collar or metal band fixed round a box, such as a column box to resist the pressure of freshly placed concrete [ see also 3.353(a)].

Strike Cl 3.296

To remove formwork after the concrete has hardened.

Striking Piece Cl 3.297

A narrow, often splayed, member intended to facilitate striking in a confined space.

Striking Time Cl 3.298

The time specified for the earliest removal of forms and other support from the concrete.

Strip a) Softwood strip Cl 3.299

A piece of square-sawn timber under 50 mm thick and under 100 mm wide. b) Hardwood strip — A piece of square-sawn timber usually 50 mm or under thick and 50 mm to 140 mm wide.

Strip, To Cl 3.300

See 3.296.

Stripping Piece Cl 3.301

See 3.297.

Stripping Time Cl 3.302

See 3.298.

Strongback Cl 3.303

A soldier, often of framed construction, for heavy duty application.

Strut Cl 3.304

A member in compression.

Stud Cl 3.305

A vertical or horizontal stiffener to the back of the form sheeting.

Subsiding Cl 3.306

See 3.206.

Surface Cl 3.307

Active Agent — See 3.309.

Surface Timber Cl 3.308

See 3.218.

Surfactant ( Surface Cl 3.309

Active Agent or Activating Agent) — A chemical which lowers the surface tension of water.

Note — Surfactants are used in mould oils to reduce the occurrence of blowholes in the concrete face.

Suspended Formwork Cl 3.310

Formwork suspended on hangers.

Table Form Cl 3.311

Formwork for suspended floors which is built up into the form of a table. It stands on the floor previously cast and is lowered and moved in one piece.

Tamper Cl 3.312

A timber or metal beam spanning between edge forms or screed rails and used for compacting concrete.

Note — S 1 A tamper may be constructed so that it also acts as a screed board. 2 A tamper may also be equipped with one or more vibrators. IS 6461 (Part 5) : 2024 11

Telescopic Centre Cl 3.313

See 3.136.

Telescopic Form Cl 3.314

A form used for work, such as tunnelling, which when struck reduces to a size small enough to enable it to pass through similar forms already in position for concreting.

Telltale Cl 3.316

Any device designed to indicate movement of formwork.

Template Cl 3.317

See 3.318.

Thickness Cl 3.319

To plane timber on opposite faces, usually simultaneously, to produce a uniform thickness.

Through Tie Cl 3.320

A form tie which passes through the concrete and is withdrawn when the forms are struck.

Tie Cl 3.321

See 3.147.

Tilting Table Cl 3.322

A table on which a vertical concrete component is cast horizontally, and which is tilted into a vertical or near vertical position to allow the component to be lifted in its natural position.

Tilt Cl 3.323

Up Construction — The on-site casting of walls horizontally so that they have only to be tilted through 90º to gain their permanent position.

Tilt Cl 3.324

Up Form — A wall form which is built on the ground beside the wall to be cast and then rotated into the vertical plane.

Tolerance Cl 3.325

The difference between the limits between which a size dimension or position should lie (see also 3.102).

Tongue Cl 3.326

A projection on the edge of a board formed by rebating the arris of both faces. It is most usually used for tongued and grooved boarding (see also 3.198).

Tongued and Grooved Boarding Cl 3.327

Boarding laid edge to edge and jointed by a tongue on the edge of one board which fits into a corresponding groove in the edge of the adjacent board (see also 3.198).

Top Form Cl 3.328

A form to the top surface of the concrete where this slopes too steeply to be cast without containment.

Trammel Cl 3.329

An instrument for describing circles or ellipses.

Trapped Form Cl 3.331

A form which is lost when no opening is left in the permanent structure through which it can be removed (see 3.339), or which has to be destroyed in striking because of the configuration of the concrete.

Travelling Formwork (Mobile Form or Moving Formwork) Cl 3.332

Formwork, such as that used for walls and tunnel linings carried on wheels or rollers so that it may be struck and moved for re-use without dismantling.

Trestle Cl 3.333

A structure for temporary or permanent support which gains its stability by having its main members at an inclination to the vertical.

Triple Wedges Cl 3.334

A system of folding wedges using three instead of two wedges.

Trough Form Cl 3.335

A form which produces an inverted-trough shaped concrete soffit.

Vacuum Form Work Cl 3.336

Formwork that incorporates a lining through which a vacuum is applied to a face of concrete to improve its compaction.

Veneer Cl 3.337

A thin sheet of wood produced by rotary cutting or slicing.

Vibrator Cl 3.338

A mechanical device for compacting concrete by imparting vibrations to it (see also 3.120, 3.170 and 3.225).

Void Box Cl 3.339

A trapped form used to create a completely enclosed space within the concrete.

Waffle Form Cl 3.340

A hollow fo rm, usually square on p lan and domed in elevation, used fo r forming the recesses or coffers in a waffle slab.

Waffle Pan Cl 3.341

See 3.340.

Waffle Slab Cl 3.342

A concrete slab designed to span in two directions and containing recesses, which are square on plan, in its under side. IS 6461 (Part 5) : 2024 12

Waling Cl 3.343

A long horizontal member acting as a beam and used in conjunction with form ties, struts or strong backs to support and prevent movement of forms.

Wall Clamp Cl 3.344

Two vertical members connected together to form an adjustable yoke to support wall forms in such a way as to avoid the use of form ties through the concrete.