A Study on Ultra High Performance Concrete Us...

A Study on Ultra High Performance Concrete Using Minerals Admixtures and Steel Fibers

Author Name : Lalit Rathee, Naveen Hooda

ABSTRACT  Ultra-High Performance Concrete (UHPC) is a relatively new construction material, which is a combination of high performance concrete, minerals admixture and steel fibers. The compressive strength reaches beyond 150 MPa, which allows the construction of sustainable and economic buildings with an extraordinarily slim design. In general the aim is to achieve such high strength keeping the cement content under permissible limits. The aim herein is to develop a concrete mix incorporating silica fume, nano silica and ground granulated blast furnace slag (GGBS) with the addition of different percentages of steel fibers, which provides for high performance, durability and better serviceability in addition to overall economy in the long run. In this study, the compressive strength of UHPC is studied closely for different percentages of steel fibers with three w/b ratios (0.24, 0.22, and 0.20). The purpose is to have such proportions of materials, including cement replacement materials like silica fume, nano-silica, GGBS etc., which on mixing would be able to provide compressive strengths in the range of 125 to 150 MPa at 28 days. The studies were carried at an early age of 7 days as well as. The workability of the different mixtures was constantly maintained by optimum usage of super plasticizers. The results showed that with the increase in the amount of steel fibers the compressive strength of the matrix increased. The maximum strength of UHPC, which was achieved under laboratory conditions, was 155 MPa, after 28 days of curing. This strength was achieved for the mix where in the overall binder content included 7% silica fume, 3% nano silica, 10% GGBS (with remaining 80% as cement content) along with the addition of 1.25% steel fiber.