Maturity functions for concrete made with various cements and admixtures N.J. CARINO National Institute of Standards and Technology, Gaithersburg, MD, USA R.C. TANK Narmada Hydro Project, Gujarat, India

The regression constants in Eqs. (5) and (6) were obtained by ordinary least squares analysis using natural-logarithm transformations of the equations.

3.3 Relative strength gain The authors have proposed13 that a unique relationship exists between relative strength gain and equivalent age for a given concrete mixture. Relative strength is the ratio of strength to the limiting strength when the concrete is fully matured. The relationship is as follows:

1 + K (t e - t o r ) (7)

where t e = equivalent age at the reference temperature, days,

t o r = age at the start of strength development at the reference temperature, and

kr = rate constant at the reference temperature.