Admixtures are materials in the shape of powder or fluids that are included into the concrete to present it sure properties not obtainable with simple concrete mixes. Admixtures are defined as additions "built as the concrete combine is staying prepared". Their skepticism was reinforced via the Cass Report from Britain, https://bookmarking1.com/story19767289/concrete-reinforced-with-rebar-can-be-fun-for-anyone