This paper describes the application of a novel actuator/sensor technology for monitoring concrete at early age. A device is designed to generate and detect highly nonlinear solitary waves (HNSWs) in a chain of steel beads. Two experiments were conducted. In the first experiment, the propagation of the HNSWs in the chain was recorded. In particular, the reflections at the interface between the chain and a composite layer consisting of a thin aluminum plate and the concrete were observed. It was found that the travelling time of HNSWs of the reflected pulses depend on the boundary conditions of the chain, so it changes as the stiffness and strength of concrete develop during the hydration process. In the second experiment, a similar actuator was used to transmit mechanical waves inside concrete. These waves were then detected by an embedded commercial transducer. The change of frequency components of the stress waves in the fresh concrete was monitored and used to interpret the initial set of the concrete. The results of these two experiments were compared to outcomes of the penetration resistance test (ASTM C403) conventionally used to determine the time of setting. We found that the proposed nondestructive evaluation method can be used in fresh concrete although more tests are needed to prove repeatability under various concrete mixtures.© (2011) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.