Maturity method to predict the evolution of the properties of sprayed concrete

• The maturity method estimates the strength of concrete during construction.
• This method is not currently used for sprayed concrete.
• New maturity curves and equations are proposed.
• An adaptation of the maturity method is proposed to be used for sprayed concrete.

The maturity method provides a simple approach for assessing the strength evolution of concrete. Although it is already used in the precast industry, no reported applications with sprayed concrete may be found in the literature. Such concrete presents singular characteristics due to the spraying process and, in some cases, due to the introduction of accelerators that modify the kinetics of cement hydration. Consequently, the traditional equations that relate the evolution of mechanical properties and the maturity index might not apply in this case. The objective of this study is to adapt the maturity method to sprayed concrete. An experimental program was conducted with 24 concrete mixes sprayed in laboratory and tested for the evolution of temperature and compressive strength. An alternative equation was proposed to relate the maturity index and the mechanical properties. Subsequently, finite element models were developed to generalize the maturity curves considering the local design parameters.