Concrete Hardstand

Commencing construction works for NSTA Hardstand Project - 8 000 sq. m fibre-reinforced concrete hardstand.

Concrete dowelsThis project was designed by GDK and aims at constructing a concrete hardstand ontop of an existing gravel parking area in NSTA, suitable for the heaviest military vehicles.

The initial assumptions for the design calculus included the following:
• A minimum subgrade modulus k=0,075N/mm3 is reached;
• Concrete class to be used – C30/37as per EN 206;
• Fibres used as concrete reinforcement, of kind and quantity so that an equivalent flexural strength ratio of at least 0,3 is achieved. For this project, a Propex macro synthetic fibres Enduro HPP45, together with micro-synthetic fibres Fibermesh 150 are recommended;
• Construction and expansion joints spaced at max 24 meters. Contraction joints at max 6 meters; 
• Load transfer by adjacent fields is done by 25mm diameter round dowels of steel B235 with length of 500mm, spaced at 300mm;
• Slab thickness 220 mm;

Water mitigation is done by using heavy-duty cast iron linear drainage elements, nicely concreted in the hardstand, channelling the rain water through two properly dimensioned oil-water separators.

A real challenge for this project is its short period of execution in combination with the logistical difficulties of providing the necessary amounts of top quality concrete. Also, locally soft spots of the subgrade are to be strengthened by using geocell technology.