Experimental study on the strength development and setting time of wet-mix shotcrete with alkali-free accelerator

The utilization of concrete with a sprayed method requires a specific characteristic, which is faster strength development and higher setting time. This requirement implemented to ensure the workability of the concrete work that means the concrete could easily be placed and stabilize when sprayed on the surface. Thus, this research focused on studying the strength development and setting time by introducing of accelerating admixture (SA160) at several levels of admixture (0, 3, 7, and 10 %) that experimentally investigated by compressive test and penetration test. The concrete cylinder specimens which tested at various age (1, 7, 14, and 28 days) reveal that the addition of accelerating admixture at the level of 10 % shows a good agreement with the targeted strength (18 MPa) achieved at 14 days curing age. Furthermore, the setting time of the shotcrete started after 7 minutes after the accelerator mixed with fresh concrete and continue to 17 minutes (final setting).