A second degree polynomial to calculate Pr for any given percentage of cement
replacement by pozzolan for each group can be determined if three points of the equation
are known. For each group, the data of the three points are known: two points in Table 5-
5 and the third point would be Prp= 0 in the mix with plain cement.
The general format of the equation is:
Prp = a(Rp)2 + b(Rp) + c Equation 5-3
Where:
Prp : Percentage of reduction in the pick temperature,
a, b and c: Constants,
Rp : Percentage of pozzolan in the mix.
a, b and c constants were determined by solving the equation for the known three
points. The amount of contents for each data group are shown in
Table 5-6 Constant Factors of Pr Equation
Constants
No. Data Group Description Cons
a b c
1 Cement + Fly Ash, 730F Placing Temperature 0.59 0.41 0.00
2 Cement + Fly Ash, 950F Placing Temperature 0.59 0.17 0.00
3 Cement + Slag, 730F Placing Temperature 0.50 -0.03 0.00
4 Cement + Slag, 950F Placing Temperature 0.85 -0.38 0.00
The relationship between Prp, Rp, and Different Placing Temperatures is shown in
Figure 5-8. As it can be seen, higher placing temperature has a smaller reducing effect on
the peak temperature.
As suggested by ACI committee 207, the adiabatic temperature rise curves must be
modified for mixes with pozzolans. One way is to calculate equivalent cement content