MEASUREMENT OF HARDENED STATE OF ASPHALT-PAVED ROAD AND DEVICE THEREOF

摘要

PURPOSE:To carry out the stable traffic opening instruction by correctly recognizing the shoulder characteristic which appears in the change of the received wave level through the lapse of time without being influenced by the cooling condition and solar radiation condition, as for the hardened state measurement of an asphalt paved road for measuring the hardened state of the asphalt after the completion of the pavement construction by utilizing the propagation characteristic of the ultrasonic wave and the device thereof. CONSTITUTION:Each time when a certain time lapses, the level V of the received wave which is formed after the ultrasonic wave projected from an ultrasonic wave transducer 10 for transmission propagates in an asphalt paved part 30 and reaches an ultrasonic transducer 12 for reception is measured. From the result of this measurement, the increase ratio (V1/Vu) of the received wave level V1 before a certain time is measured for the received wave level Vu at present is calculated, and when the increase ratio of the reception level is less than a previously determined threshold value, e.g. the increase ratio of the reception level at each minute is less than 1.015, the attainment to a hardened state permitting traffic is judged, and a traffic opening instruction is generated.