Matches in UGent Biblio for { ?s ?p The setting of mortar or concrete can be monitored by measuring the velocity of ultrasonic p-waves sent through a fresh sample at regular intervals. However, the wave energy or the frequency spectrum might contain even more information. To investigate their use in the characterization of setting behaviour, ultrasonic measurements were performed on concrete and mortar mixtures with an increasing percentage blast-furnace slag or fly ash and on mixtures with several types of blast-furnace slag cement. The change of the received energy in time was compared to the result of the penetration resistance test and the frequency spectra were collected in a three-way array (sample x frequency x concrete age) and analysed with multi-way techniques (PARAFAC and PARAFAC2) to quantify mutual differences. The change of the energy during setting was similar to that of the ultrasonic velocity. Replacement of Portland cement by blast-furnace slag or fly ash causes retardation in the increase of both quantities. For the energy measurements, the thresholds E/Eref = 0.02 and 0.13 and proposed to easily determine respectively initial and final setting. Regarding the analysis of the received frequency spectrum, the samples could be sorted by the multi-way models in agreement with the expected setting behaviour.. }
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- aggregation abstract "The setting of mortar or concrete can be monitored by measuring the velocity of ultrasonic p-waves sent through a fresh sample at regular intervals. However, the wave energy or the frequency spectrum might contain even more information. To investigate their use in the characterization of setting behaviour, ultrasonic measurements were performed on concrete and mortar mixtures with an increasing percentage blast-furnace slag or fly ash and on mixtures with several types of blast-furnace slag cement. The change of the received energy in time was compared to the result of the penetration resistance test and the frequency spectra were collected in a three-way array (sample x frequency x concrete age) and analysed with multi-way techniques (PARAFAC and PARAFAC2) to quantify mutual differences. The change of the energy during setting was similar to that of the ultrasonic velocity. Replacement of Portland cement by blast-furnace slag or fly ash causes retardation in the increase of both quantities. For the energy measurements, the thresholds E/Eref = 0.02 and 0.13 and proposed to easily determine respectively initial and final setting. Regarding the analysis of the received frequency spectrum, the samples could be sorted by the multi-way models in agreement with the expected setting behaviour.".