Roman concrete

Stony Brook University did a fairly long term study of the use of concrete, a catalyst and coal ash which did not affect the soil it was in. Proposed was seawalls and other mediating structures.

I read a woman in a private company had invented a mixing machine that incorporated small pieces of metal, based on stress and need, in the concrete as it was transported to the forms. The shapes were researched and appeared shaped like carabiners, different size and diameters, allowed concrete in new forms, now stronger than with rebar. Perhaps a stronger "slurry wall" would also be built, and the interface at bedrock, more secure than the flat-ends of a rebar cage.

Law requires rebar to be cleaned, labor intensive, when reused for example in a bridge. There was a multiple machine that uses high pressure water to break, remove old concrete and clean the rebar using water pressure. Faster than by hand, the concrete is poured as part of this "train", which however is very loud.

Read more at: http://phys.org/news/2013-06-roman-seawater-concrete-secret-carbon.html#jCp