28 bridges with piers standing in water

A retrofitting programme covering 28 bridges in one state needed reinforcement layouts, moisture extents and corrosion extents before design could be fixed. The substructures were in continuous contact with water, and conventional scanning had not returned usable data on them.

Water attacks radar from both sides. Its dielectric constant is about 81 against 6 for dry concrete, so the pulse slows and every depth reads wrong. The ionic pore solution also raises conductivity, so the signal is absorbed and the lower half of the record goes blank. Taken at face value that reads as a clean pier. It is the opposite.

Treated the signal loss as the measurement. Calibration was carried out separately for submerged, splash and dry bands on the same element, gain was fitted to the attenuation actually measured, and the datasets were mapped in MATLAB three ways: attenuation, arrival time shift, and reflection polarity. Together those separate moisture ingress from delamination from section loss at the bar, readings that a single radargram confuses.

All 28 structures surveyed and reported in one comparable format, each with its achieved depth of investigation stated, so the owner could rank intervention across the network.

The HILTI PS 1000 X-Scan is a three antenna ground penetrating radar system that produces plan view images of concrete, not the single line trace of a covermeter or a rebar scanner. It records a 600 by 600 mm image scan grid in a single set up, extendable to 1200 mm by 1200 mm for larger elements, and detects to a stated maximum of 300 mm in concrete. Default settings assume dry, ordinary concrete, so we acquire in expert mode with the phase of the signal preserved and calibrate the dielectric constant on the element in front of us, processed in PROFIS Detection together with our own MATLAB routines.

Enquiry. Send the element type, thickness, exposure condition and what you need to locate on WhatsApp. Photographs, drawings and any previous scan output help us assess it fast.

Plan. We check access, moisture, exposure and reinforcement congestion against your target, confirm radar is the right test, and schedule the visit.

Scan and mark. Calibrated on the element, scanned in an orthogonal grid, and marked directly on the surface for your coring or cutting crew, same visit.

Report, if needed. Depth slices, plan extents and permissible core diameters, issued as a written report when your project requires formal documentation.