Rebar:
Bar Splice
avoid welding
wedged sleeve bar splice
Bundling:
up to 4 #11
Bending & Welding Limitations
bent without heating
max. heat 1,500 F
bars partly embedded in concrete
may not be bend
no welding of crossing bars
no tack welding
creates metallurgical notch
exceptions:
engineer's permission
Shipping Limitations:
max. width 8'-0"
max. length 60'-0"
max. height 7'-4"
7'-4"
60'
Hooks:
standard sizes
according to ACI 318
Spiral Reinforcement
No 3 9" min. diameter
No 4 12" min. diameter
Strength Requirements:
Columns 3,000-7,000 psi
Strength Variations due to:
Batching
Mixing
Handling
Compacting
Curing
Environmental Factors
Loads on Formwork:
pressure of concrete on vertical forms
p = 150 + 9000 R
T
p = lateral pressure psf
R = rate of filling, ft/h
T = temperature of concrete F
Column Clamps
steel strapping
light-gauge
econ-o-clamps
symons column clamps
recommended spacing of clamps
Maximum permissible w/c ratios:
Concrete attacked by Substances:
Durability of Concrete:
resistance to wear
abrasion
scratching
scrubbing
scuffing
weathering
freeze-thaw
ozone
fading
chemical fumes
bactericidal
UV ultraviolet radiation
adhesion of coating
delamination
blistering
dimensional stability
shrinkage
expansion
volume change
mechanical properties
resistance to splitting
bursting
tearing
fatigue
Construction Joint:
are formed when fresh concrete is placed against hardened concrete
v - key
u - key
Expansion Joints
are provided in long components to relieve
compressive stresses that would otherwise result from temperature
rise.
Contraction Joints = Control Joints
are provided to permit concrete to contract during a drop in temperature and to permit drying shrinkage without resulting uncontrolled random cracking
h/4 to h/3