Operation - skilsaw SPT5007-EA Manual De Instrucciones

To reduce the risk of injury,
WARNING
read the Operating/Safety in-
structions included with SKILSAW SPT79A.
They contain information not covered in this in-
struction manual .
SAWING CONTRACTION JOINTS
Internal stresses in concrete develop as the con-
crete begins to set . Left unattended, these internal
stresses develop random cracks. Contraction
joints, sawed at an early stage, prevent random
cracking and ensure that the crack is formed
where intended – right under the contraction joint
(Fig . 11) .
IMPORTANT: Do not connect the saw to a water
feed . Early entry sawing does not require water to
make the cut .
Contraction joints should be cut as soon as the
concrete can support the weight of the saw and
the user without leaving marks or damaging the
surface . Check the concrete surface in 15-minute
intervals until the above conditions are met.
Some of the following factors affect spacing be-
tween contraction joints:
• Thickness of the concrete
• Kind, amount, and locations of reinforcement
• Type and quantity of concrete-cement
(Shrinkage potential), type of aggregate,
water to cement ratio, and concrete tempera-
ture
• Base friction
• Slab restraints
• Layout of foundations, racks, pits, equipment
pad, trenches, etc .
• Environmental factors such as temperature,
wind, and relative humidity
• Concrete curing methods .

Operation

FIG. 11
Contraction Joint
-13-
Random Cracking
Controlled Cracking