Composition and Manufacture

Forticrete Stepoc blocks are manufactured to finetolerances using aggregates which satisfy BS 882 andcement to BS12. They are manufactured at a plantwhich is registered under the BSI Registered FirmsScheme, a third party Quality Assurance schemebased 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: 16.5kg 400 x 225 x 256mm: 19.85kg

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

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

190 2000 2400 2110

256 2000 2400 2120

Concrete InfillSTEPOC 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 specificapplications refer to BS 8110 Part 1 1997.

Agrément ApprovalThe British Board of Agrément hasapproved Stepoc for use as set outin Agrément Certificate No. 98/3450.

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

Resistance to Sulphate AttackStepoc has adequate resistance to Class 3 sulphateground conditions.

SPECIFIC ATION

Forticrete Ltd, Hillhead Quarry, Harpur Hill, Buxton, Derbyshire SK17 9PS.Tel: 01298 23333 Fax: 01298 23000

Information and advice can also be obtained by calling the Forticrete Technical Hotline on: Freephone 0800 262136 or by e-mail at Technical@Forticrete.co.uk

Information on the complete range of Forticrete products can be found on the Internetat www.Forticrete.co.uk

® FORTICRETE is a registered trademark of Forticrete Ltd. © 2003 Forticrete Ltd.

A p r i l 2 0 0 3

C I / S f B

S T E P O C ®

S Y S T E M

F f 2

STRENGTH

Tests undertaken by Ceram Research yielded high values for characteristic compresive strength (fk) for Stepoc walls. The 256mm 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 in aclass III mortar in accordance with BS 5628: Part 1: 1992. Similarly, 190mm Stepoc provides a higher vertical load resistance thana 215mm wall constructed from standard format brickwork, with a compressive strength of 50 N/mm2 laid in 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

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.

DESIGNINGWITH STEPOC®

DESIGN CHARTS

These 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 atultimate limit state, i.e. factored. Forunreinforced Stepoc, a partial factor ofsafety of 3.1 for material strength shouldbe used, to account for the specialcategory of manufacturing controloperated by Forticrete. For reinforcedStepoc, the partial factor of safety shouldbe taken as 2 and 1.15 for steel inaccordance with part 2 of the masonrycode and Forticrete’s quality controlprocedures.

EXAMPLE - STEPOCSTRENGTH UNDER

VERTICAL LOAD

EXAMPLE - STEPOCSTRENGTH IN BENDINGFROM LATERAL LOAD

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

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

)

NB The use of this chart is intended for guidance only at a preliminary stage. A full design check shouldbe undertaken by the designer in accordance with BS 5628: part 2: 1995 ‘Structural use of Reinforced

and Pre-stressed Masonry’, accounting for ultimate and serviceability limit states as required.

NB The use of this chart is for guidance only at a preliminary stage. A full design check should beundertaken 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.

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

400 133

33

190186 186190 256

33

33

33

835093402274010 10

400 133

28

134126 126134 190

28

28

2888459540225408 8

BRITISHBOARD OFAGRÉMENT

CERTIFICATE No 98/3450

F

Ty

pe

19

0

400 x 225 x 190 standard 133 x 225 x 190 1/3 length

Ty

pe

25

6

400 x 225 x 256 standard 133 x 225 x 256 1/3 length

DELIVERY, STORAGEAND HANDLING

Delivery and OffloadingStepoc blocks are supplied on pallets for offloadingby forklift truck or crane.

StorageBlocks should be stored on reasonably dry, firm,level ground with protection from rain and snow. Ifblocks are accidentally wetted, provision should bemade for free circulation of air round the stack sothat the units may dry out prior to being used.Blocks should not be stacked directly on sulphate-bearing ground, clinker or ashes, unlessprecautions are taken to prevent chemicals beingdrawn into them by rising moisture, nor should theybe stacked on newly-cast slabs until the concrete isfully matured.

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

By reference to the laterally loadeddesign chart, to sustain a bendingmoment of 55KNM, 1250mm2 /m ofhigh yield vertical reinforcement isrequired within the voids of 256mmStepoc.

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

www.Forticrete.co.uk

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

Agrément Certificate No. 98/3450.

BRITISHBOARD OFAGRÉMENT

CERTIFICATE No 98/3450MEMBERConstruction CPD Certification Service

F O R T I C R E T EE N G I N E E R I N G

P R O D U C T S