Ultrasonic pulses are send through concrete from one probe to another (probes located in parallel tubes), the CSL procedure inspects the drilled shaft structural integrity, and extent and location of defects, if any. The time between pulse generation, signal reception (“First Arrival Time” or “FAT”) and the strength of the received signal give a relative measure of the quality of concrete between transmitter and receiver. Dividing the distance between transmitter and receiver by the FAT value yields the approximate concrete wave speed which also is a relative indicator of concrete quality. For equidistant tubes, uniform concrete between the test tubes yields consistent arrival times with reasonable pulse wave speed and good signal strengths. Non-uniformities such as contaminated or soft concrete, honeycombing, voids and inclusions exhibit delayed arrival times with reduced signal strength. 

CSL procedures are standardized by ASTM 6760, Standard Test Method for Integrity Testing of Concrete Deep Foundations by Ultrasonic Crosshole Testing. Standards are available in many other countries. 

Cross hole Sonic Logging Unit from Piletest, UK

3-D Tomography

High Strain Pile Dynamic Analysis (PDA) 

High Strain Pile Dynamic Testing captures data on force and acceleration of a pile during impact. The data is used to evaluate the bearing capacity and the integrity of the pile as well as hammer performance, pile stresses and soil dynamics characteristics, such as soil damping coefficients and quake values. Pile integrity, which is accurately evaluated, would allow the engineer to accept/reject the pile without any delay.

Actual driving stresses and hammer performance data obtained during pile monitoring can reduce pile damages. Piles no longer have to be overdriven resulting in lower foundation cost. Random testing of installed piles would also provide the design engineer/ contractor/ client measure of confidence in the foundation as he would probably not be at the site all the time to witness the pile installation. It is also to ensure that the installed piles can function as designed.

PDA procedures are standardized by ASTM D-4945-96 and ICE Piling Specifications (UK) Standard

PDA Testing at PITB Tower, Lahore.

Instrumented Pile Load Testing, Karachi

Additional Testing
GSA in collaboration with its foreign associates designs and undertakes instrumented pile load test, geotechnical site monitoring and specialized pile load testing in a cost affective manner. 

Tel.:+92-42-5854628-29
Fax:+92-42-5864656                    
E-Mail: info@geoscience.com.pk