Cambridge Electric Cement

> What is the strength of the resulting cement?

According to the article, the clinker has the same composition as the "normal" one. The strength _should_ therefore be the same, but must still be tested of course. In case it is different, the analysis why this is the case would certainly be interesting.

> What is the energy input needed per kilo of output steel/concrete?

... compared to separate processing for steel and clinker. The article makes it sound like we get the clinker "for free" because the energy input is required to make steel anyway, but there is no word about whether it actually needs the same amount of energy with the added slag, or more.

Indeed. Just like "steel", there isn't just one "cement". Different cements have different uses for different concretes.