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CIVIL

E NGINEERING

PRODUCTS

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STEPOC® SYSTEM

The British Board of Agrémenthas approved Stepoc for use as set out in

Agrément Certificate No. 98/3450.

BRITISHBOARD OFAGRÉMENT

CERTIFICATE No 98/3450

MEMBERConstruction CPD Certification Service

FULL LENGTHBLOCK

1/3 LENGTHBLOCK

FULL LENGTHPLAIN END

1/3 LENGTHPLAIN END

Stepoc combines the ease of blockwork

with the versatility of in-situ concrete, and

yet is faster to apply than both, making it

an ideal component in fast-track

construction for:

• Retaining walls

• Sheer walls

• Laterally-loaded panels

• Blast panels

• Bund walls

• Basement walls

and any applications that require higher

compressive or lateral loads than those

achievable with standard masonry.

Built dry, with no mortar joint, and

requiring no special on-site skills or

techniques, as each unit weighs less than

20 kgs, they are bonded with liquid

concrete, which is poured down through

the interconnected cavities in the blocks.

The blocks’ unique design creates a

cascade or waterfall filling effect which

ensures a smooth filling of the poured

concrete, forcing out air and eliminating

segregation, to create walls which have

immense compressive and lateral strength.

The system is available in two widths –

190mm and 256mm and comprises four

units – a full length and a 1/3rd length

standard block and a full length and 1/3rd

length plain end block for use at corners

and ends of walls.

The blocks are laid to a running bond, in a

combination of 1/3 rd and full lengths,

which automatically creates the correct

pattern to produce the ‘waterfall’ effect.

Corners, T-junctions and cross junctions

are created using a combination of all four

units and specific data sheets are available

to illustrate these.

Filling is accomplished by a concrete

pump. The concrete should possess the

characteristic strength specified by the

structural engineer, not less than 35N/mm2

and designed to be pumpable through the

specific pump to be used, possessing a

slump of no less than 150mm. The

maximum aggregate size should not

exceed 10mm and the mix should contain

no less than 300kg of Ordinary Portland

Cement per cubic metre of fresh concrete.

Alternative methods to pumping may be

used, provided that the fresh concrete can

flow in a similar manner to pumped

concrete and that the method of

transportation and placing does not incur

an additional risk to the stability of the

wall. Mechanical vibration is unnecessary,

and should not be used.

Stepoc is a system of highly-engineered and dimensionally co-ordinated building modules which are designed to readilyaccept both vertical and horizontal reinforcement for use where structural performance is the prime consideration.

THE FASTER, MORE ECONOMICAL WAY TOBUILD WALLS WITH EXCEPTIONAL STRENGTH

STEPOC® SYSTEM

Design ChartsThese charts are intended to display therange of strengths attainable under verticalload and bending when Stepoc walls aredesigned in accordance with BS 5628‘Code of Practice for Use of Masonry’

The design loads referred to are at ultimatelimit state, i.e. factored. For unreinforcedstepoc, a partial factor of safety of 3.1 formaterial strength should be used, toaccount for the special category ofmanufacturing control operated byForticrete. For reinforced Stepoc, the partialfactor of safety should be taken as 2 and1.15 for steel in accordance with part 2 ofthe masonry code and Forticrete’s qualitycontrol procedures.

EXAMPLE - STEPOCSTRENGTH IN BENDING

FROM LATERAL LOAD

By reference to the laterally loaded designchart, to sustain a bending moment of55KNM, 1250mm2 /m of high yieldvertical reinforcement is required within thevoids of 256mm Stepoc.

From the reinforcement table, it can beseen that this is easily provided by T16bars at 133mm c/c.

AREA OF REINFORCEMENT(MM2/M) FOR VARIOUS BARDIAMETERS TO COINCIDE

WITH VOID PATTERN

Bar Bar centresdiameter 133mm 266mm 399mm

10 590 295 196

12 850 425 283

16 1511 755 503

20 2362 1181 787

EXAMPLE - STEPOCSTRENGTH UNDER

VERTICAL LOAD

By reference to the design chart forvertically-loaded 256mm Stepoc, a wallwith an eccentricity of 0.10t (25.6mm),with an effective height of 5000mm cansustain a vertical design load (factored) of950 KN/m.

DESIGNING WITH STEPOC®

StrengthTests undertaken by Ceram Research yielded high values for characteristic compresive strength (fk) for Stepoc walls. The256mm Stepoc achieved an fk of 18N/mm2 and 190mm Stepoc achieved 14N/mm2.

For axially loaded stocky walls not subject to the effects of buckling, the 256mm Stepoc wall provides a higher vertical loadresistance than a 328mm wall constructed from standard format bricks, with a compressive strength of 70 N/mm2, laid ina class III mortar in accordance with BS 5628: Part 1: 1992. Similarly, 190mm Stepoc provides a higher vertical loadresistance than a 215mm wall constructed from standard format brickwork, with a compressive strength of 50 N/mm2 laidin class III mortar.

400 600 800 1000 1200 1400 1600

70

65

60

55

50

45

40

35

30

25

20

15

10

5

Area of high yield reinforcement (mm2/m)

Max Moment 30.5 KNM

Desi

gn

Mom

en

t K

NM

per

metr

e (

fact

ore

d)

Max Moment 68.5 KNM

Laterally LOaded Wall (reinforced)

256 STEPOC WALL

190 STEPOC WALL

NB The use of this chart is intended for guidance only at a preliminary stage. A full designcheck should be undertaken by the designer in accordance with BS 5628: part 2: 1995

‘Structural use of Reinforced and Pre-stressed Masonry’, accounting for ultimate andserviceability limit states as required.

VERTICally LOaded 256mm UNREINFORCED STEPOC Wall

e ≤ 0.05t

e ≤ 0.10t

e ≤ 0.20t

e ≤ 0.30t

1 2 3 4 5 6 7

1600

1500

1400

1300

1200

1100

1000

900

800

700

600

500

400

300

200

Effective Height of Wall (metres)

Desi

gn

Vert

ica

l Lo

ad

Resi

sta

nce

(K

N/m

)

VERTICally LOaded 190mmUNREINFORCED STEPOC Wall

e ≤ 0.05t

e ≤ 0.20t

e ≤ 0.30t

1 2 3 4 5

1600

1500

1400

1300

1200

1100

1000

900

800

700

600

500

400

300

200

Effective Height of Wall (metres)

Desi

gn

Vert

ica

l Lo

ad

Resi

sta

nce

(K

N/m

)

e ≤ 0.10t

NB The use of this chart is for guidance only at a preliminary stage. A full design check shouldbe undertaken by the designer in accordance with BS 5628:Part 1: 1992 ‘Structural Use of

Unreinforced Masonry’. The effective height is not neccessarily the overall height of the wall.

The open jaws of Stepoc unitslocate with the ribbed end ofthe next ensuring precisealignment.

A combination of standardfull length and 1/3rd lengthunits creates the bondingpattern.

Laid dry, walls can be built upat great speed with nospecialist skills required.

Vertical and horizontalreinforcement, positioned priorto pouring, create a greatstrength simply and efficiently.

Laid to a 1/3rd runningbond, the Stepoc systemautomatically creates aunique internalconfiguration, producing acascade filling effect whenthe concrete is poured.

The concrete is pumpedalong the blocks and isguided inside the wall to atriangle configuration whichexpels air.

Blocks can be cut on sitesimply to allow continuity ofreinforcement.

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LAYING STEPOC IS FAST AND EASY

Pump in concrete, directing the hose along the block in order to reduce the risk of displacing the units. To allowinitial setting, 24 hours should elapse between infills of concrete. Concrete should finish 50-75mm below the topof the block to provide a key for subsequent courses.

Check vertical faces forplumb on completion ofalternate courses. Dry sandmay be used as a packing, toensure alignment.

Stack blocks dry to a 1/3rdrunning bond and to a heightnot exceeding 2.25m beforethe first pour.

Position horizontalreinforcement to engineer’srequirements.

Lay the first course, beddingin mortar to a stretched line.Walls should generally startat a corner with the openends of the block runningtowards the centre of thewall. The open ends of theblocks should engage theribbed full end of theadjacent block.

Check that the base is levelWhen casting thefoundation, verticalreinforcing bars may bepositioned, generally at 133centres or multiples thereof.Data sheets are availablefor details at corners, stopends etc.

1 2 3

4 5 6

7

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® FORTICRETE is a registered trademark of Forticrete Ltd.© 2005 Forticrete Ltd.

400 133

33

190186 186190 256

33

33

33

835093402274010 10

400 133

28

134126 126134 190

28

28

2888459540225408 8

400 x 225 x 190 standard

400 x 225 x 256 standard

For technical information, call the Forticrete Technical Hotline:

FREEPHONE 0800 262136 or E-mail at technical@forticrete.co.uk.

Information on the complete range of Forticrete products can be

found on the Internet: www.forticrete.co.uk

For sales & product enquiries contact:

Forticrete Ltd., Hillhead Quarry, Harpur Hill,

Buxton, Derbyshire SK17 9PS.

Tel: 01298 23333, Fax: 01298 23000,

E-mail: engsales@forticrete.com

DELIVERY, STORAGE AND HANDLING

Delivery and OffloadingStepoc blocks are supplied on pallets for offloading by forklifttruck or crane.

StorageBlocks should be stored on reasonably dry, firm, level groundwith protection from rain and snow. If blocks are accidentallywetted, provision should be made for free circulation of airround the stack so that the units may dry out prior to beingused. Blocks should not be stacked directly on sulphate-bearing ground, clinker or ashes, unless precautions aretaken to prevent chemicals being drawn into them by risingmoisture, nor should they be stacked on newly-cast slabsuntil the concrete is fully matured.

HandlingMechanical handling should not be used after the blockshave been offloaded from the wooden pallet.

Composition and ManufactureForticrete Stepoc blocks are manufactured to fine tolerancesusing aggregates which satisfy BS 882 and cement to BS12.They are manufactured at a plant which is registered underthe BSI Registered Firms Scheme, a third party qualityassurance scheme based on BS EN ISO 9002.

DimensionsForticrete Stepoc blocks are available in two standard sizes:

400 x 225 x 190mm400 x 225 x 256mm

WeightStepoc average weights per block are as follows:400 x 225 x 190mm: 16.5kg400 x 225 x 256mm: 19.85kg

Characteristic Compressive Strength (fk)190mm – 14.0 N/mm2 256mm – 18.0 N/mm2

DENSITY

STEPOC BLOCK CONCRETE OVERALL BLOCK DENSITY INFILL DENSITY(mm) (kg/m3) (kg/m3) (kg/m3)

190 2000 2400 2110

256 2000 2400 2120

CONCRETE INFILL

STEPOC BLOCK (mm) m3 per m2 of wall

190 0.11

256 0.15

Manufacturing Tolerances (mm)Height: +2, -2Length: +2, -2Width: +2, -2

Fire ResistanceMinimum fire resistance: 2 hours. For specific applicationsrefer to BS 8110 Part 1 1997.

Agrément ApprovalThe British Board of Agrément hasapproved Stepoc for use as setout in Agrément CertificateNo. 98/3450.

Resistance to Frost DamageThe Stepoc system is resistant to the freeze-thaw conditionsthat are likely to occur below a damp proof course.

Resistance to Sulphate AttackStepoc has adequate resistance to Class 3 sulphate groundconditions.

TYPE 190

TYPE 256

133 x 225 x 256 1/3 length

133 x 225 x 190 1/3 length

BRITISHBOARD OFAGRÉMENT

CERTIFICATE No 98/3450

SPECIFICATIONS