Title: Experimental Study on Creep and Durability of High-Early-Strength Self-Consolidating Concrete for Precast Elements

Author(s): Young Hoon Kim, David Trejo, Mary Beth D. Hueste, and Jeong Joo Kim

Publication: Materials Journal

Volume: 108

Issue: 2

Appears on pages(s): 128-138

Keywords: creep; diffusivity; durability; freezing and thawing; permeability; precast; prediction model; prestressed members; self-consolidating concrete

DOI: 10.14359/51682306

Date: 3/1/2011

Abstract:
Self-consolidating concrete (SCC) typically has high cement paste volumes to achieve the desired fresh characteristics. These high paste volumes may lead to increased creep, which can increase the concrete compressive strain in prestressed concrete members. This increased compressive strain can lead to a reduction in the prestressing force for these elements. Reduced prestressing forces can result in higher deflections and reduced capacities. Accurate estimates of the creep of SCC prestressed members are needed so that these structural elements can be properly designed. The creep of high-early-strength (HES) SCC mixtures was assessed in this study. In addition to the creep characteristics, the durability characteristics of HES SCC need to be assessed. Because sustainability and durability are critical for long-lasting, economically viable systems, implementing the use of a new material that exhibits poor durability can be costly and unsafe. The permeability, diffusivity, and freezing-and-thawing resistance of HES SCC mixtures were assessed in this study. An assessment of the creep compliance of HES SCC values indicates that the 2006 American Association of State Highway Transportation Officials (AASHTO) Load and Resistance Factor Design Specifications predicted the creep compliance with the highest accuracy among all the models considered in this research. The 2004 AASHTO, ACI 209, and CEB-FIP MC90-99 models provide fairly good predictions of the creep compliance for both the conventional concrete (CC) and HES SCC mixture prediction equations. It is noted that for more accurate predictions, however, all models should be calibrated with data from full-scale structural elements. The durability measurements indicate similar performances for the HES SCC mixtures relative to the CC mixtures; however, the 5 ksi (35 MPa) release strength CC and HES SCC mixtures exhibited low resistance to freezing-and-thawing cycles.