Cold Joint in a Concrete Column
LDM Scanning was instructed to undertake a Ground Penetrating Radar (GPR) survey of a concrete column. The purpose of the investigation was to establish any evidence of significant voiding and honeycombing could be detected in the immediate vicinity of a known cold joint in a concrete column.
A GSSI SIR 3000 and 4000 Ground Penetrating Radar systems were used with 2.6GHz, 1.5GHz and 900MHz antennas.
GPR scans can be conducted using antennas with different central frequencies. A higher frequency antenna provides better resolution and more detail, however penetration depth is limited. For this survey two different antennas were used giving a range of penetration depths and resolutions. the 2.6GHz antenna would typically penetrate to a depth of 300mm in concrete and was considered the most appropriate for detecting honeycombing, albeit at a relatively shallow depth, while the 1.5GHz antenna would typically penetrate to a depth of 400mm in concrete, thus resolving slightly deeper features.