The concrete maturity concept : an introduction to the local context

Abstract

Maturity takes into account the combined effects of temperature and time on the strength development of concrete, providing a reliable estimate for in-situ concrete strength without the need of physically testing specimens. The origins of this concept can be traced back to a series of research papers dealing with the steam curing of concrete in Europe in the late 1940s and 1950s. This research consists of a theoretical and experimental examination of the maturity method and its applicability to the local context. Common locally used concrete mixes were cured at a reference temperature of 20°C and strength testing was carried out at a number of ages, from which a strength-maturity relationship specific to each mixture was established. The most appropriate maturity function for each concrete mix was determined by testing a second batch of concrete having the same constituents and proportions as in the previous mixes cured at 10°C and 30°C, representing the local mean mm1mum winter temperature and mean maximum summer temperature respectively, and comparing the actual strengths obtained with estimated strengths. The equivalent age method based on the function suggested by Freiesleben Hansen and Pedersen resulted in the most accurate strength estimates for two of the mixes (both containing CEM I), whilst the function suggested by Rastrup provided the most accurate strength estimates for the rest of the mixes (the majority containing CEM II). However, it was established that for maximum accuracy and reliability in strength estimates, especially when applying the method to large construction projects, the datum temperature and activation energy of each concrete mix should be determined.