Blast performance assessment in plexiglas models by measurement of specific surface area - A new approach

There are many methods available for assessment of blast performance. Blast results like degree of fragmentation, diggability of toe, profile of muckpile and back break as well as side effects like fly rock, ground vibrations and stemming ejection are generally considered for assessment of blast performance. Attempts were made at CMRI to assess the blast performance by measurement of specific surface area (SSA). This was done by conducting experiments in Plexiglas models by incorporating various blast patterns like air decking, varying stemming material, stiffness, hole size and hole deviation. Model blocks were blasted with detonators placed in blastholes of 8-mm diameter and 15 cm depth. Blast results like fracture surface area and number of fragments were observed. The fractures generated in the models by varying the above design parameters were compared with a conventional model blast with standard blast parameters. The SSA approach for the evaluation of blast results is a relatively new method. The results of all the models are in line with established facts. The paper presents the insight derived from each blast with different design conditions to stress the need for measuring SSA for blast performance assessment.