Discussion in this guide is limited to high-strength concrete produced using conventional materials and production methods. Consideration of silica fume and ground granulated blast furnace slag (GGBFS) is beyond the scope of this document. Information on proportioning of silica fume concrete is limited at this time. ACI Committee 234@ Silica Fume in Concrete@ is developing information on the use of silica fume for a committee report. Proportioning GGBFS concrete is discussed in ACI 226-1R (now ACI Committee 233). When additional data becomes available@ it is expected that an ACI guide for proportioning concrete with these materials will be developed. Currently@ silica fume and GGBFS suppliers@ as well as experienced concrete suppliers@ represent the best source of proportioning information for these materials.High-strength concrete is defined as concrete that has a specified compressive strength ?c???of 6000 psi or greater. This guide is intended to cover field strengths up to 12@000 psi as a practical working range@ although greater strengths may be obtained. Recommendations are based on current practice and information from contractors@ concrete suppliers@ and engineers who have been involved in projects dealing with high-strength concrete. For a more complete list of references and available publications on the topic@ the reader should refer to ACI 363R.