US 5,675,085 A · Method and apparatus for measuring depth of crack for reinforced concrete construction

Abstract

By arranging a pair of an ultrasonic wave transmitting sensor and an ultrasonic wave receiving sensor in opposition across a crack in a reinforced concrete construction. An ultrasonic wave is transmitted from the ultrasonic wave transmitting sensor at a first position. A reflected wave is then received by the ultrasonic wave receiving sensor at the first position. Also, the ultrasonic wave is transmitted from the ultrasonic wave transmitting sensor at a second position. A reflected wave is then received by the ultrasonic wave receiving sensor at the second position. The received waves at two positions are provided mutual phase shift for a predetermined period and summed in reversed phase for deriving a rise time of the wave reflected from the crack. By this, even when reinforcement is arranged in the concrete, the noise component superimposed on the received wave due to presence of the reinforcement can be eliminated to permit high precision measurement of the depth of the crack irrespective of the presence of the reinforcement at high density.

Claims7

Dependent claims

A method for measuring a depth of a crack in a reinforced concrete construction, comprising the steps of:

providing an ultrasonic wave transmitting sensor and an ultrasonic wave receiving sensor in opposition across a crack at a first position;
transmitting an ultrasonic wave by said ultrasonic wave transmitting sensor at said first position;
receiving a reflected ultrasonic wave by said ultrasonic wave receiving sensor at said first position;
positioning said ultrasonic wave transmitting sensor and said ultrasonic wave receiving sensor at a second position distanced from said first position along the crack;
transmitting an ultrasonic wave from said ultrasonic wave transmitting portion at said second position;
receiving a reflected ultrasonic wave by said ultrasonic wave receiving sensor at said second position;
determining a mutual phase shift .DELTA.t between the received wave at said first position and the received wave at said second position;
phase shifting the received waves such that components of the received waves representing secondary reflections are in reversed phases;
summing the phase shifted received waves to cancel the components representing secondary reflections and thereby detect a rise time of a wave reflected from said crack;
and
deriving a depth of the crack based on said rise time.

8 more elements

Dependencies are inferred from the claim text.

Method and apparatus for measuring depth of crack for reinforced concrete construction

Life of this patent

Method and apparatus for measuring depth of crack for reinforced concrete construction

Life of this patent

Abstract

Claims7