ABSTRACT
The s p e c i f i c charge was 0.42 kg/m . I n s i m p l i f i e d terms, t h i s may be defined as the t o t a l weight of charge d i v i d e d by the volume of m a t e r i a l . I n i t i a t i o n was by detonators w i t h 25 ms delay. From the production p o i n t of view, the method worked very w e l l i n s p i t e of the f a c t t h a t no major e f f o r t was made to f a c i l i t a t e the a c t u a l work. An edge beam, 37 m long could be demolished i n 3-4 hours. Complete c l o s u r e of the bridge was n e c e s s a r y only f o r a few minutes during the a c t u a l b l a s t i n g . With a charge weight of 10 g and spacing of 300 mm, the edge beam was s a t i s f a c t o r i l y demolished. Before the new concrete was placed, the b l a s t e d edge was c u t back to sound con c r e t e . The appearance of the edge beam before and a f t e r i s shown i n F i g . 17.
