Who is familar whit this kind of cement, and his benefits.

I found this link but I dont know anything about it. http://www.concrete.org/Technical/CCT/FlashHelp/B.htm#blast_furnace_slag

http://www.slagcement.org/shared/layouts/amazonian.jsp?_event=view&_id=120130_U128801__165966

Laboratory and field studies were conducted on blast-furnace slag aggregates to establish nationwide material standards and recommended practices. Absorption of air-cooled blast-furnace slag kept in water was 2 to 9 times that of natural gravel, while that under pressure of 2.0 MPa was 1.2 to 4 times that kept in water. Absorption characteristics of air-cooled blast-furnace slag under pressure varied depending on its porosity and pore size distribution. Field studies were conducted on the pumpability of blast-furnace slag aggregate concretes. Air-entrained concretes containing air-cooled and granulated blast-furnace slags, and those containing crushed stone and natural sand were pumped and tested for pumping pressure and properties before and after pump-ing. Concrete with air-cooled blast-furnace slag indicated higher pumping pressure than that with crushed stone due to pressure absorption, while no significant change was found for granulated blast-furnace slag concrete. It is concluded that blast-furnace slag aggregate concrete is pumpable without significant slump-loss when such aggregate does not have excessive absorption, and is properly presoaked in water before the mixing of concrete.

http://www.concrete.org/PUBS/JOURNALS/AbstractDetails.asp?ID=6744

We have been getting it for several years and it acts just like cement cause it is.  Just made from blast furnace waste which costs less.  No drawback, but I'm no expert.

The main benefit for the operator is that the seting time of the cement is twice as long  as the portland cement.les hot loads,les boom party's les stress.

The bad part foe being a finisher is the slower set time. Weve been using it foe years in WI. The redi mix companies used to get it for free from power plants just for hauling it away. Now they charge for it,but it's very cheap compared to imported portland cement

my experience is that it needs to have a little more water than normal but besides that its just mud.

We reckon on a 6 hr delay in setting when using this stuff, it pumps virtually the same, most powerfloaters wont have  it in the mix, going for straight cement mixes instead.  Readymix companies tend to use it to keep the cost down, and on a big thick pour, or  in the summer its better because it doesnt heat up as fast and therefore you dont get cracks as much.  If you wet it right up then the slag will seperate out leaving a black film, like coal dust on the surface.