May 2003 saw Sunland Construction commence construction of the world’s tallest residential tower situated at Clifford Street, Surfers Paradise. The Q1 tower is a total of 80 levels and reaches 275 metres skyward. The design is by Sunland's in-house design team, with support from, Brian Whaley (Whaley Consulting group).

Significant design criteria
The significant design criterion for the Q1 tower’s concrete requirements was to provide an innovative concrete solution to ensure the concrete could be pumped to great heights.

Concrete used
The concrete used in the construction of Q1 in Surfers Paradise included:

  • 65MPa – for vertical columns from the ground level to level 10
  • 50MPa – for vertical columns for levels 10 through to level 30
  • 40MPa – for vertical columns from levels 30 through to level 80

The suspended slabs were 40MPa from ground level to level 80.

Solutions developed
Holcim  developed an innovative method of adapting the mix design to ensure the pumpability of the concrete as the Q1 building grew. With four changes in concrete mix design, Holcim provided concrete that was capable of being pumped 62 metres in the horizontal direction and a further 240 metres in the vertical direction.

Each mix design change involved a change in aggregate proportions and admixtures to ensure that the optimum pumpability was achieved without segregation or pump blockages, whilst still maintaining the engineering properties of the concrete mix.