Construction Business News - The first cement-free ultra-low carbon concrete block has been launched in the UK today which promises up to 73 CO2 savings compared to traditional concrete blocks. The new sustainable concrete block, Greenbloc, is being launched by CCP, part of SigmaRoc plc. Greenbloc is an ultra-low carbon alternative to traditional cement-based concrete blocks and is designed to help reduce the construction industry s dependency upon cement the world s third highest source of man-made CO2 as a key ingredient in concrete manufacturing.