Development of an inline water mains inspection technology: Detection of acidic deterioration in cement-based water pipes with ultrasonic pulse-echo technique

The condition of a great part of the drinking water network in the Netherlands is unknown. In order to efficiently identify the assets that are close to their lifetime expectancy, a non-destructive evaluation method was developed based on ultrasonic testing. The water network is composed mostly by polyvinyl chloride (~50%) and cement-based (~30%) pipes. In this work, the degradation due to acidic attack in cement-based drinking water pipes was investigated. Mortar blocks were manufactured and degraded in a hydrochloric acid solution. The amount of degradation was derived by measuring the overall ultrasonic pulse velocity in the specimen. Moreover, two factors played a vital role in the detection of acid induced damage: the high damping of the piezoelectric element, resulting in low resonance and the processing algorithm. A 0.5 MHz central frequency transducer is found to be the most suitable to detect acidic damage in cement-based structures