Matches in UGent Biblio for { ?s ?p Research on ultrasonic methods to monitor the setting of concrete has mainly focussed on the wave velocity as a useful quantity. To investigate the application of also the wave energy as a parameter, the ultrasonic wave transmission technique was performed on several concrete and mortar samples in which increasing amounts of the Portland cement was replaced by blast-furnace slag or fly ash. The transmitted ultrasonic wave energy was calculated as the sum of the squared amplitudes of the received signal, divided by the reference energy (E/Eref). The incrase of the energy during setting was retarded if ordinary Portland cement was replaced by blast-furnace slag or fly ash. The final setting determined by the standard penetration resistance test occurred shortly after the peak in the derivative curve of the ultrasonic energy. In addidtion, the values E/Eref = 0.02 and 0.15 are proposed to easily calculate respectively initial and final setting based on the ultrasonic energy measurements. Due to the sensitivity of the energy measurement to the quality of the sensor contact, care should be taken to limit shrinkage of the cementitious samples.. }
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- aggregation abstract "Research on ultrasonic methods to monitor the setting of concrete has mainly focussed on the wave velocity as a useful quantity. To investigate the application of also the wave energy as a parameter, the ultrasonic wave transmission technique was performed on several concrete and mortar samples in which increasing amounts of the Portland cement was replaced by blast-furnace slag or fly ash. The transmitted ultrasonic wave energy was calculated as the sum of the squared amplitudes of the received signal, divided by the reference energy (E/Eref). The incrase of the energy during setting was retarded if ordinary Portland cement was replaced by blast-furnace slag or fly ash. The final setting determined by the standard penetration resistance test occurred shortly after the peak in the derivative curve of the ultrasonic energy. In addidtion, the values E/Eref = 0.02 and 0.15 are proposed to easily calculate respectively initial and final setting based on the ultrasonic energy measurements. Due to the sensitivity of the energy measurement to the quality of the sensor contact, care should be taken to limit shrinkage of the cementitious samples.".