Lightweight Concrete for High Strength - Expanded Shale & Clay

h: relative humidity in decimals
k c
⎡ t
⎢
⎢ 26 ⋅ exp 0.36
= ⎢
⎢ t
⎢ 45 + t
⎢⎣
⎤
{ ⋅V
} + t ⎥
⎥ ⎡1.80
+ 1.77 ⋅ exp{ − 0.54 ⋅V
}
S
⎥ ⋅ ⎢
⎥ ⎢
⎣
⎥
⎥⎦
2.587
⎤
S ⎥ ; size factor
⎥
⎦
until ⎧ ⎡
⎤⎫
day n
⎪ ⎢ 4000
⎥⎪
t = ∑ ∆ti
⋅ exp⎨−
⎢
−13.
65⎥⎬
; maturity of concrete (days) after “n” days
⎪
T ( ∆t
)
⎢273
+
i
⎥⎪
⎩ ⎣
T 0 ⎦⎭
V: specimen volume (in 3 )
S: specimen surface area (in 2 )
k
f
= 1
f
c
'
; concrete strength factor
0.67 +
9
f c ’: compressive strength of concrete cylinders at 28 days (ksi)
Drying Shrinkage Model. ASSHTO-LRFD general expression for shrinkage is the same as ACI
expression (Equation B.3) including the values for f of 35 and 55 for moist and steam curing,
respectively. The expression for calculating ultimate shrinkage is different from ACI expression,
and it is presented in Equation B.6.
(ε ) = K ⋅ k ⋅ k
(B.6)
sh
u
s
h
where
(ε sh ) u : ultimate shrinkage strain (in/in)
⎧510
µε for moist curing
K = ⎨
; ultimate shrinkage base value
⎩560
µε for steam curing
k s
=
⎡
⎢
⎢
⎢
⎢
⎢
⎣
26 ⋅ exp 0.36
( t − t )
0
{ ⋅V
} + ( t − t0
)
45
S
( t − t0
)
+ ( t − t )
0
⎤
⎥ ⎡
⎤
⎥ 1064 − 0.94 ⋅V
⋅ ⎢
S ⎥
⎥
; size factor
⎢ 923 ⎥
⎥ ⎣
⎦
⎥
⎦
B-8