Lightweight Concrete for High Strength - Expanded Shale & Clay

⎡ t
⎢
⎢ 26 ⋅ exp 0.36
k =
S
vs ⎢
⎢
t
⎢ 45 + t
⎣
V: specimen volume (in 3 )
⎤
{ ⋅V
} + t ⎥
⎥ ⎡1.80
+ 1.77 ⋅ exp{ − 0.54 ⋅V
}
S: specimen surface area (in 2 )
⎥ ⋅ ⎢
⎥ ⎢
⎣
⎥
⎦
4.8
k = f c
1.645 + f '
; concrete strength factor
c
2.587
f c ’: compressive strength of concrete cylinders at 28 days (ksi)
⎤
S ⎥ ; size factor
⎥
⎦
k H
= 1 .58 − 0. 83⋅
h ; ambient relative humidity factor
h: relative humidity in decimals
k t '
⎧ 0.7 ⎫
= 0.65 ⋅ exp⎨
⎬ ; maturity at loading factor
⎩t'
+ 0.57 ⎭
k σ
{ ⋅ ( Γ − 0.4)
}
⎧exp 1.5
⎪
= ⎨
⎪
⎩ 1.0 for Γ ≤ 0.4
Γ: stress-to-strength ratio at loading
for 0.4 ≤ Γ ≤ 0.6
; stress-to-strength ratio factor
k m
( 1 − exp{ − 0.59 ⋅ }) 5. 73
= 1 + 0.65 ⋅
m : moist curing period factor
m: moist curing period (days)
d
= t'
0.356 + 0.09 ⋅ t'
: maturity for 50% of ultimate creep coefficient
Drying Shrinkage Model. Equation B.8 shows Shams and Kahn drying shrinkage expression.
⎡ t − t ⎤
o
ε
sh
( t, to
) = ε
sh∞
⋅ kvs
⋅ k
H
⋅ kt
⋅ ⎢ ⎥ (B.8)
o
⎣ f + ( t − to
) ⎦
0.5
B-10