7-day flexural strength to determine 7-day tensile strength

huangyhg

7-day flexural strength to determine 7-day tensile strength
i using ufc 3-260-02 pavement design for airfields, 30 june 2001 to calculate the percentage of reinforcing steel required in the longitudinal direction.
one of the parameters is f(subt) = 7-day tensile strength of the concrete in psi determined using the splitting tensile test.  this reference has a figure 5-1 to convert the 7-day flexural strenght into tensile strenght.
can you guys give me advice or point me to a reference in calculating the 7-day flexural strength for 3,000 psi, 4,000 and 5,000 psi so that i can find the 7-day tensile strength form this figuere.
thanks

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beams are made of the paving mix and stored for three point loading results.  the compressive strength has an assumed correlation to flexural strength, aci 318 9.5.2.3, fr = 7.5 x sq root (f'c).
is the modulus of rupture fr the same thing as flexure strength?
do you know how would i determine the 7-day flexural strength?
thanks