Dears; I face a challenge to upgrade a solid mat slab foundation retrofitting works. At the beginning the structural design has been done for 3B+G+10 Apartment building and with this design only mat foundation has been Poured. Two years later the client changed his idea and want to construct 3B+G+21 story building with different column and shear wall grid system. But the mat slab foundation was already casted with the old design. Additional 600mm concrete mat slab is required in order to resist the new design. Really I worry how to make the new concrete old concrete monotonically and act as one system. If you have any experience and recommendations how to make the old and new concrete act monotonically, please share me.
