3. Typical slab layouts - concretesociety.org.nzconcretesociety.org.nz/Downloads/Slabs/3.1 Fibre Slabs.pdf · Specification and design of commercial concrete slabs on grade • Slab

Specification and design of commercial concrete

slabs on grade

3. Typical slab layouts


slabs on grade

3.1 Typical layout of fibre slabs

Alan Ross Sean Page-WoodGeneral Manager or Business Development ManagerBOSFA BOSFA


slabs on grade

• Slab usage and requirements

• Different types of loads

• Ultimate Limit State design

• Fibre types

• Joints vs. controlled cracking, Slab types and Detailing – Part 2

PRESENTATION OVERVIEW


slabs on grade

Jointed concrete slabs

• Traditional pavements are based on experience to avoid cracks:

• limited joint distance

• saw-cut or saw-cut free floors in indoor environment

• saw-cut floors in outdoor environment

• no connections to fixed points

• rectangular field shape

• length/width ratio ≤ 1:1.5

• minimum thicknesses

• etc.


slabs on grade

Conventional solutions vs CombiSlab

Conventional pavements

For regular jointed slabs

For pavements without specified SLS demands => crack width

Cracks up to about 0.5 mm accepted or repaired

Steel fibre only, Conventional reinforcement or PT

Combi Slab

For pavements with a specified crack width to be verified, e.g. 0.2 mm

Example: fluid tight pavements

Joint free slabs or pavements

Pavements with restraint

Replace heavy double mesh or heavy rebar reinforcement


slabs on grade

Reinforced Concrete:

Conventionally reinforced Section


slabs on grade

Conventional reinforcement


slabs on grade

Combined reinforcement


slabs on grade

Reinforced Concrete:

Effect on Crack Width: Combined Reinforcement

Combined Reinforcement:


slabs on grade

Serviceability = nominal crack width

German Std DIN1045

� dry environment: 0.5 mm

� soil or moisture: 0.3 mm

� chlorides: 0.1 - 0.3 mm (+ possibly coated)

� coated: 0.2 mm

�water tight: 0.1 – 0.2 mm

� environmental: 0.1 – 0.2 mm

� chemical: 0.1 – 0.2 mm (+ possibly coated)

AusRoads

� CRCP (typically) 0.3mm – 0.5mm


slabs on grade


slabs on grade


slabs on grade

Slab types

Saw cut

o Internal and external fibre only slab

Saw cut free

o Internal unrestrained fibre only slab

o Internal and external unrestrained Combi Slab

Joint free (no saw cuts or movement joints)

o Internal and external Combi Slab


slabs on grade


slabs on grade


slabs on grade

Slab types

Saw cut


Saw cut free






slabs on grade

Sawn Joints


slabs on grade


slabs on grade

Joints


slabs on grade

Joints Maintenance


slabs on grade


slabs on grade


slabs on grade


slabs on grade

Slab types

Saw cut


Saw cut free






slabs on grade

Smooth flat base and enclosed environment


slabs on grade

Smooth flat base

Use 2 Layers of Plastic

0-10mm sand

0 to -10mm Subbase Tolerance


slabs on grade

Obstructions


slabs on grade

Dowels


slabs on grade

Why Armoured Joints are so good

• Protect the slab edge from fretting

• Sawn joint less slabs or tied sawn

joints have 15-20mm opening width.

• Help prevent crack propagation

• Hold the whole slab together

• Spread loads across to more dowels

• Nice straight and flush


slabs on grade

Armoured Joints


slabs on grade

Armoured Joints


slabs on grade

Planning for Joints

1:1.5 max

Max 900-1200sqm

25-35m plan dimensions

Keep on column grids


slabs on grade

Planning for Joints

40m

25m


slabs on grade

Planning for Joints

40m

25m


slabs on grade

Planning for Joints


slabs on grade

Planning for Joints


slabs on grade

Planning for Joints

Let slabs shrink to one

point in the middle


slabs on grade

Planning for Joints


slabs on grade


slabs on grade


slabs on grade


slabs on grade

Slab types

Saw cut


Saw cut free






slabs on grade

Planning for Joints

40m

25m


slabs on grade

Planning for Joints


slabs on grade

Planning for Joints


slabs on grade


slabs on grade


slabs on grade

4 years later


slabs on grade


slabs on grade

Slab types

Saw cut


Saw cut free






slabs on grade


slabs on grade

Detailing at points of high or differential stress


slabs on grade


slabs on grade


slabs on grade


slabs on grade


slabs on grade

Re-Entrant Corner

If not detailed

more than likely

we will see a

crack propagate

Trimmer bars

will reduce this

risk


slabs on grade


slabs on grade


slabs on grade

Tied Joints

Congested Reo


slabs on grade

Tied Joints

Mesh/Reo Staggered tie bars


slabs on grade


slabs on grade 6

3


slabs on grade


slabs on grade


slabs on grade


slabs on grade

Thank you and Questions.

Documents

3. Typical slab layouts - concretesociety.org.nzconcretesociety.org.nz/Downloads/Slabs/3.1 Fibre Slabs.pdf · Specification and design of commercial concrete slabs on grade • Slab