Carillion's large portfolio of Public Private Partnerships (PPPs) helped the support services company post a rise in profits and revenues in the six months to June 30.Pre-tax profits climbed to £51.9m from £27m over the same period the previous year as revenues rose to £2.72bn from £2.41bn.The board has proposed an interim dividend of 4.6p, up 12% from last year's payout at the half year stage.'A high quality order book, a resilient business mix, strong positions in our chosen market sectors and a robust balance sheet continue to underpin our expectation that, despite challenging market conditions, Carillion will deliver materially enhanced earnings in 2009,' said chairman Philip Rogerson.The firm said it expects the outlook for PPPs to remain positive, while overall trading will remain challenging.