The central measure is a UK guarantee designed to underwrite financing for £40bn of stalled projects within the National Infrastructure Plan.
He also released £6bn in temporary Government loans to ensure around 30 public-private partnership infrastructure projects can go ahead.
The new UK loan guarantees and lending for big building projects follow months of criticism that the government has failed to generate jobs and growth.
The Government will now use its balance sheet to shoulder major project risk by offering guarantees for projects that are ready or nearly ready, with the first expected to be awarded in the autumn.
As well as infrastructure projects, the loans will also be available for housing, health and education projects.