My concern is, if this stuff works, how much will it work? Will it repair itself in the same area more than once? What is to stop the bacteria from forming a big lump on the surface after they bridge the crack's gap. Is the replacement material even nearly as strong as the original concrete or will it just break again under less stress? If the intended use of this for building construction or surfaces to walk on? I can see it being used in 1-3 story buildings as material, but any where solid concrete has to be used instead of those hollow cinder blocks, I can't see it being possible, much less if water is needed to activate it.
Being able to repair small cracks to keep water out would go a long way to minimize the freeze/thaw damage that makes small cracks into big cracks. Even without the same strength as uncracked concrete, concrete with some small filled cracks will perform much better and last much longer than concrete with growing numbers of growing sized cracks.