Ultrastrength Flowable Concrete Made with High Volumes of Supplementary Cementitious Materials

This paper investigates the feasibility of developing ultrastrength high-performance flowable concretes made with a high content of supplementary cementitious materials (SCMs). A total of 25 concrete mixtures were prepared and tested. Mixtures were divided into three different groups with water-to-cementitious materials ratios (w/cm) of 0.3, 0.33, and 0.37, respectively. All mixtures were prepared to achieve a target slump flow equal to or higher than 500mm (24in.). The control mixture for each group was prepared with 100% portland cement whereas all other mixtures were designed to have up to 70% of portland cement replaced by a combination of SCMs such as class C or class F fly-ash, granulated blast furnace slag, and silica fume. The properties of fresh concrete investigated in this study include flowability, deformability, filling capacity, air content, and resistance to segregation. In addition, the compressive strength at 1, 7, 28, and 90days, the unrestrained shrinkage up to 90days, and the concrete permeability were also investigated. A critical analysis for the properties of fresh and hardened concrete shows that ultrastrength high-performance flowable concrete can be developed with low w/cm and up to 70% of cement replaced by supplementary cementitious materials. Properties of such concrete are superior to those of the control mixture made with 100% portland cement. (C) 2013 American Society of Civil Engineers.