Sprayed concrete differs from ordinary concrete through application technique and addition of set accelerator that gives immediate stiffening. The alkali free set accelerator consists of sulphate and aluminate and forms an ettringite network that gives a stiff but not hard matrix. This work has investigated the interaction between the early ettringite matrix and the proper cement hydration and the development of the interfacial zone between concrete and rock. This has been correlated to the development of the bond strength.