Lightweight Concrete for High Strength - Expanded Shale & Clay

The 50% and 90% of the 620-day creep coefficient were reached after 16 and 250 days
regardless the type of HPLC.
Figure 4.3 presents the average shrinkage obtained from 8,000-psi and 10,000-psi mixes
in logarithmic time scale. The 620-day shrinkage was 818 and 610 µε for 8,000-psi and 10,000-
psi HPLC, respectively. At very early ages (less than one day), shrinkage of the 10,000-psi mix
was considerably greater than that of the 8,000-psi mix. After one day, the shrinkage rate of the
10,000-psi mix slowed down, and measured shrinkage was much lower than for the 8,000-psi
HPLC. The 50% and 90% of the 620-day shrinkage was reached after 27 and 170 days for 8,000-
psi HPLC and after 55 and 170 days for 10,000-psi mix.
800
Shrinkage (µε)
700
600
500
400
300
8,000-psi HPLC
10,000-psi HPLC
FHWA HPC Grade 2 Upper Limit
FHWA HPC Grade 3 Upper Limit
200
100
0
0.01 0.10 1.00 10.0 100 1000
Time (days)
Figure 4.3. Average shrinkage of 8,000-psi and 10,000-psi HPLC in logarithmic time scale.
4.3 Creep and Shrinkage Test Results vs. Model Estimates
The best shrinkage estimate was given by AASHTO-LRFD and Shams and Kahn’s
model, for 8,000-psi and 10,000-psi HPLC, respectively. Those models underestimated
shrinkage by only 5% and 4%, respectively. Creep coefficient of 8,000-psi HPLC was best
predicted by AASHTO-LRFD model for normal strength concrete with an underestimate of 8%
4-4