Method for seamless connection of concrete of new and old buildings

The invention discloses a method for seamless connection of concrete of new and old buildings. The method comprises the following steps: (1) downwards cutting butt joint floor surfaces of the new and old buildings for 5cm-8cm; and cleaning crushed stones and concrete blocks; (2) drilling holes in two butt joint surfaces, which are obtained by cutting, through an impact drill; punching expansion bolts into the drilled holes and connecting steel bars between the two corresponding expansion bolts; fixing the two ends of the steel bars on the corresponding expansion bolts respectively; arranging distribution steel bars vertical to the steel bars on the fixed steel bars to form a grid shape; (3) spaying the two butt joint surfaces for 3min-5min with water; (4) pouring concrete and compacting by utilizing a vibrator; vibrating for 2min-3min to eliminate air bubbles in the concrete; and (5) paving a sun-proof or a rain-shielding object on two newly-poured butt joint surfaces. The method has the characteristics of se