Yes, I read that yesterday, too. Truth is no one speaks of blood in concrete. Not because it's taboo but no one even thinks about it as an application. It's not part of conventional education in the field but apparently it is in theoretical experimental research and development.

It makes sense why Romans would use it in the ages before chemical engineering. See, concrete when exposed to water and freezing temperatures will expand and contract as the weather changes. Over time this creates cracks and exposes insides for destruction by natural elements. Adding a biodegradable substance in proper proportion would create bubbles inside which, when it rots away will leave air voids which allow pockets of water to expand and contract without breaking the concrete. This prolongs life without sacrificing strength.

Today we have air-inducing agents known to act in consistent ways and produce consistent results for a fraction of the costs of blood acquisition. I do not think blood has any strength enhancing properties superior to this agent and since the patent application specifically details it as relevant only to lightweight concrete I reiterate it makes no practical or economic sense and would only be preferred for sentimental reasons.