Materials firm Aardvark is selling concrete that allows rainwater to pass directly through it to improve flood drainage in urban areas.

The porous material, already widely used in the US, lets water seep through to the surrounding ground at a rate of 8-12 gallons per minute per square foot.

Where Keller made its money

Keller鈥檚 first-half turnover split

UK 拢44.8m (2007: 拢35.4m)
US 拢245.5m (拢232.7m)
Europe, Middle East and Asia 拢204.4m (136.2m)
Australia 拢74m (拢39.6m)