Pile Integrity Testing

Pulse Echo Integrity Testing (PIT)

This integrity test is so quick and simple to execute that it permits verifying the absence of major anomalies on all foundation elements of a job site. It is performed with the Pile Integrity Tester on any type of concrete deep foundation.

Pulse Echo Integrity Testing is a non destructive pile testing method that verifies the integrity of driven concrete or timber piles, auger cast-in-place piles and drilled shafts. If major defects exist, the test estimates their magnitude and location; it may also determine pile length.

The Pulse Echo Test, also known as Pile Integrity Test, Sonic Echo Test and Low Strain Test, is normally performed after pile installation and curing. It requires minimal pile preparation, and has been routinely used worldwide for many years. Because of its simplicity, speed of execution and low cost, it can be performed on 100% of the piles on a given a job site.

The pile top has to be hit with a hand held hammer. The impact of the hammer generates a compressive stress wave in the pile, and an accelerometer placed on top of the pile monitors the motion associated with this wave. The stress wave propagates down the pile shaft, and is reflected when it encounters either the pile toe or a non-uniformity of the shaft. These reflections cause a change in the acceleration signal measured on the pile top, which is picked up and processed by the Pile Integrity Tester (PIT) equipment and interpreted by an experienced SLP engineer.

SLP performs this foundation integrity test in accordance with ASTM D5882-07 – Standard Test Method for Low Strain Integrity Testing of Piles

Typical PIT result for a pile without any defects

Crosshole Sonic Logging  (CLS) Crosshole Sonic Logging (CSL) verifies the integrity of drilled shafts. Assures the absence of cracks and voids and verifies concrete quality on shafts built with inspection tubes. Field results are complemented by Tomography analysis. Drilled shafts are prepared for integrity testing by CSL during their construction, by installation of at least three tubes of 2 inch inside diameter. These tubes are usually attached to the reinforcement cage along the full length of the shafts. After concrete has been poured, the tubes are filled with water.

Cross hole sonic logging is performed with the Cross-Hole Analyzer™ (CHA) by Pile Dynamics. Starting at the bottom of the shaft, a transmitter emits an ultrasonic signal in one tube. The signal is sensed some time later by the receiver in another tube. Poor concrete between the tubes will delay or completely disrupt the signal. The The sensors (transmitter and receiver) are than moved some distance upward along the shaft and the process repeated until the entire shaft length is scanned. The engineer repeats the test for each pair of tubes, allowing for the investigation of defects both along the length and by quadrant.

SLP performs this foundation integrity test in accordance with ASTM D6760-02 – Standard Test Method for Integrity Testing of Concrete Deep Foundations by Ultrasonic Crosshole Testing

TIP - Thermal Integrity Profiling

Thermal Integrity Profiling is a technology that utilizes the heat generated by curing of concrete to assess the integrity and quality of drilled shafts, augered cast in place (ACIP) piles and other concrete foundations. From the test results, necks, bulges, variations in concrete cover and the as-built shape of the shaft, including steel cage eccentricities, can be characterized. Drilled shafts and ACIP piles are prepared for Thermal Integrity Profiling during their construction, by the installation of Thermal Wire® brand cables or access tubes. We perform this test using aThermal Integrity Profiler. When shafts are equipped with Thermal Wire cables, temperatures are automatically sampled throughout the concrete hydration process starting immediately after casting. We typically retrieve the data for analysis and reporting after 12 to 48 hours depending upon shaft diameter and mix design.