Maturity testing of lightweight self-compacting and vibrated concretes

A series of laboratory tests were carried out to investigate the effect of temperature on the early-age strength development of lightweight self-compacting and vibrated concrete mixtures. These had been developed at Queen's University Belfast as part of a Technology Strategy Board funded project aimed at developing lightweight and low energy concretes. The new mixtures incorporated high volumes of pulverised fuel ash (PFA), ground granulated blast furnace slag (GGBS), and limestone powder (LSP). Activator, i.e. sodium sulphate, was used to improve the early age strength development of vibrated concrete mixtures proportioned with PFA and GGBS. For each mixture, concrete cubes were manufactured and cured under isothermal (20 °C, 30 °C, 40 °C and 50 °C) as well as adiabatic conditions. The temperature rise under adiabatic curing conditions was also measured. The resulting isothermal strength data were analysed to determine the apparent activation energies of the binders/mixtures used. The suitability of maturity methods for predicting concrete strength development of these low energy lightweight self-compacting and vibrated concrete mixtures under non-isothermal, i.e. adiabatic, curing was assessed.