authority suspects Or Kim Peow used substandard cement and concrete.
http://www.torque.com.sg/19829/concrete-samples-collapsed-pie-worksite-sent-testing/
Concrete samples from collapsed PIE worksite being sent for testing
Investigations into the collapse of an uncompleted viaduct began on Tuesday (July 18) as workers collected concrete samples of the failed structure for analysis by the authorities.
The Straits Times understands the samples were required by the Building and Construction Authority (BCA), which is looking into why the corbels – angular structures built to support heavy loads – on the raised highway in Changi gave way at about 3.30am last Friday.
The analysis will determine, among other things, the quality of the mixture, and that it met design specifications. A lower quality concrete could be weaker than designed, and could indicate that contractors or suppliers cut corners.
Workers could be seen on Tuesday afternoon using drilling equipment at both ends of the viaduct structure where the failed corbels are located.
The BCA was unavailable for comment, while employees of Or Kim Peow – the contractor that teamed up with CPG, the corporatised entity of the former Public Works Department to secure the viaduct project with the lowest bid of $94.6 million – declined to talk to the press.
Asked why it awarded the contract to a contractor that was, at the time, being investigated for an earlier work site fatality case, the Land Transport Authority reiterated that its tender process took into account “many quality aspects”, including “track record”.
In Friday’s collapse, which killed one worker and injured 10 others – of whom two are critically injured, preliminary findings pointed to failed corbels as the cause.