Ensuring sound infrastructure

Sineco S.p.A operates in the engineering sector with special focus on the control and planning of maintenance interventions for large transport infrastructures. The company was established in 1987 by Società Iniziative Nazionali Autostradali (SINA) and other important motorway representative companies. Sineco S.p.A is also part of the Autostrada Torino Milano (ASTM) group, leader in transport infrastructures with a national motorway network of more than 1,200 kilometres.

Early detection of bridge deck damage

To have a complete assessment of the corrosion, delamination and infiltration in the bridge deck at Rio Vizzana Viaduct, a survey using GPR was performed using the RIS Hi-BrigHT. This unique GPR solution enables users to interpret data easily using software specifically designed for bridge analysis.

By processing the complete collected data set with automatic estimation algorithms, Sineco S.p.A could assess the bridge deck conditions by cross-correlating all the information extracted, such as:

• depth of the rebar layer
• concrete slab thickness
• power reflected by the rebars, and
• estimation of moisture presence by propagation velocity estimation.

Following the assessment of the deteriorated status of the concrete and rebar mesh, the bridge deck was completely removed and the data from RIS Hi-BrigHT was compared to the actual status of the bridge deck.

The system is composed of a massive antenna array of sixteen 2Gigahertz channels with 10 centimetres spacing, mounted on a lightweight and highly manoeuvrable trolley and powered by a large, 24 ampere hour (Ah) 12 Volt battery. Compared to a single antenna GPR, RIS Hi-BrigHT is 1 metre wide and can scan a bridge with passes in a single direction. Thanks to the fast data collection of IDS Georadar’s GPR system, authorities just needed to close the bridge during the survey for approximately 25 minutes for a total acquisition of 210 square metres.

"Thanks to the double polarisation of the RIS Hi-BrigHT antennas, it is possible to obtain a complete and detailed detection along each scan line over the bridge deck, instead of losing time creating a net of orthogonal ones,” said Marco Umberto Conti, geophysicist at Sineco S.p.A. “Acquisition experiences on bridge decks, demonstrated how easily and swiftly the job can be accomplished with RIS Hi-BrigHT, having benefits for both operator and customer."

Post-processing analysis and data interpretation

Map of Asphalt Thickness

In the post processing phase, Sineco S.p.A evaluated the:

• asphalt thickness
• depth of the rebar mesh and,
• visualised corrosion, concrete cover thickness and moisture in different maps.

Map of Corrosion

Map of Moisture

All this was done using IDS GeoRadar software GRED HD Bridge.

Aside from reducing the duration of traffic interruption during field operations, the denser measurements provided by RIS Hi-BrigHT yield a more accurate characterisation of the condition of the bridge deck, a better prediction of the deterioration progression, and a better assessment of the rehabilitation needs. Such comprehensive and accurate assessments can also reduce the frequency of detailed follow-up inspections. In addition, data collected from the non-destructive tests of bridge decks can complement other information to better understand life-cycle costs, deterioration mechanisms, and the effectiveness of preservation techniques at various stages of the aging process.

"The advantage for the customer is clear: short time of single line or entire carriageway closure; less time waiting for the results of such detection; and a complete dataset for a restructuring planning,” said Conti. “We have also seen through direct verification and scarifying of bridge concrete slabs that the Power Map exported using GRED HD Bridge is a very effective tool to identify areas potentially affected by the deterioration of reinforcing bars."