Title: Effect of Material Constituents on Mechanical and Fracture Mechanics Properties of Ultra-High-Performance Concrete

Author(s): Mustapha A. Ibrahim, Maen Farhat, Mohsen A. Issa, and Jessica Amanda Hasse

Publication: Materials Journal

Volume: 114

Issue: 3

Appears on pages(s): 453-465

Keywords: concrete materials; curing; flexure toughness; fracture mechanics; shrinkage; steel fibers; strength; ultra-high-performance concrete (UHPC)

DOI: 10.14359/51689717

Date: 5/1/2017

Abstract:
Optimizing ultra-high-performance concrete (UHPC) mixture design requires investigating the effect of varying the materials constituents and curing temperature on its mechanical characteristics. Therefore, a comprehensive experimental program was conducted that included studying the effect of varying the materials constituents on the mechanical and fracture mechanics properties of UHPC. The experimental program included water-cementitious materials ratio (w/cm), cementitious combination, amount of ground silica, aggregate type, maximum aggregate size, steel fiber content, and curing temperature. Higher compressive strength was achieved with higher curing temperature. The use of Class C fly ash with up to 20% replacement to cement by weight was found to be beneficial in increasing the compressive strength at later age (28 and 90 days). Moreover, reducing the ground silica content from 25% (control) to 10% as a partial replacement to fine sand and the silica fume from 25% to 20% can still yield more than 150 MPa (21.7 ksi) compressive strength at 28 days. In addition, the inclusion of steel fibers up to 2% by volume was found to significantly improve the compressive strength, ultimate flexural strength, flexure toughness, and the fracture parameters of UHPC.