CTLGroup performed an evaluation of concrete consolidation and developed repair design recommendations for the Deep Space Station (DSS) 35 reinforced concrete antenna pedestal structure. Concern was related to observed surface voiding and lack of concrete consolidation in an elevated roof slab at the Canberra Deep Space Communications Complex in Australia. The pedestal roof and walls exhibited regions of poor consolidation. Evidence of water seepage was also observed. Nondestructive testing (NDT) and coring characterized conditions on the roof slab and perimeter track wall of the antenna support structure.
The NDT results revealed that the combination of hot weather, equipment breakdown, low slump concrete mixture, and poor workmanship resulted in the observed deficiencies. CTLGroup recommended concrete repairs, leaking cracks, and joints be injected with a low viscosity, high modulus epoxy resin. Installation of a traffic-bearing elastomeric waterproofing membrane was also considered for the topside of roof slab.
