By December 2013, Ambuja Cements plans to invest Rs 1,800 crore to expand its production capacity. The company proposes to fund the project through internal accruals. It had surplus cash of Rs 7,700 crore as of December last year.Ambuja will set up a 2.2-million-tonne clinkerisation unit at Nagaur in Rajasthan. The feasibility study for the project is completed and environmental clearance has been obtained.