3. Typical slab layouts - concretesociety.org.nzconcretesociety.org.nz/Downloads/Slabs/3.1 Fibre...
Transcript of 3. Typical slab layouts - concretesociety.org.nzconcretesociety.org.nz/Downloads/Slabs/3.1 Fibre...
Specification and design of commercial concrete
slabs on grade
3.1 Typical layout of fibre slabs
Alan Ross Sean Page-WoodGeneral Manager or Business Development ManagerBOSFA BOSFA
Specification and design of commercial concrete
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
Specification and design of commercial concrete
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.
Specification and design of commercial concrete
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
Specification and design of commercial concrete
slabs on grade
Reinforced Concrete:
Conventionally reinforced Section
Specification and design of commercial concrete
slabs on grade
Reinforced Concrete:
Effect on Crack Width: Combined Reinforcement
Combined Reinforcement:
Specification and design of commercial concrete
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
Specification and design of commercial concrete
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
Specification and design of commercial concrete
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
Specification and design of commercial concrete
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
Specification and design of commercial concrete
slabs on grade
Smooth flat base and enclosed environment
Specification and design of commercial concrete
slabs on grade
Smooth flat base
Use 2 Layers of Plastic
0-10mm sand
0 to -10mm Subbase Tolerance
Specification and design of commercial concrete
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
Specification and design of commercial concrete
slabs on grade
Planning for Joints
1:1.5 max
Max 900-1200sqm
25-35m plan dimensions
Keep on column grids
Specification and design of commercial concrete
slabs on grade
Planning for Joints
Let slabs shrink to one
point in the middle
Specification and design of commercial concrete
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
Specification and design of commercial concrete
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
Specification and design of commercial concrete
slabs on grade
Detailing at points of high or differential stress
Specification and design of commercial concrete
slabs on grade
Re-Entrant Corner
If not detailed
more than likely
we will see a
crack propagate
Trimmer bars
will reduce this
risk
Specification and design of commercial concrete
slabs on grade
Tied Joints
Mesh/Reo Staggered tie bars