Dynamite was not invented and patented by Alfred Nobel until 1867. The only explosive that was used during the War Between the States would have been black powder.

Black powder is a very poor explosive and the burn is incomplete thus it is not a high explosive. It would do some damage in large quantities but it would not have the cutting capability of today's high explosives. To be able to blow a hole sufficient to destroy a railroad or bridge you would have to have a large quantity and then you would have to pack large amounts of sandbags or other material to try and direct the force of the blast down. Therefore, you often see the reference of burning bridges or tearing up the track and ties and heating the rails in order to bending so they could not be used again.

Respectfully,

Gerald D. Hodge, Jr.
M.A. Military History - Civil War Concentration
Research – Preservation
Historian: 39th Georgia Volunteer Infantry Regiment
http://39thgavolinfrgt.homestead.com/39thHomepage.html
Outpost & Dispatch Historical Research, LLC.