Abstract

The effect of coarse aggregate (CA) on the stability and mechanical performance of ultra-high-performance concrete (UHPC) was investigated. To assess UHPC stability, a unique approach was developed that utilizes specially fabricated large specimens with a depth of 400 mm. It overcomes the drawback of limited CA migration distance using small specimens, which may not replicate conditions relevant to structural applications. The spatial distributions of various constituents along the vertical casting direction were quantified through image processing technology. Results showed an approximately 12 % reduction in CA content in the top layer, while the bottom layer exhibited 12 % more CA compared to a homogeneous distribution. CA was beneficial for the global distribution of steel fibers whereas it worsened the local distribution. The deviation from a homogenous distribution for steel fibers among different layers was within 5 %. In contrast, the intralayer distribution stability index reached up to 18 %. The compressive strength of the top and bottom layers demonstrated reductions of up to 28.8 % and 31.6 %, respectively. The two middle layers exhibited compressive strengths comparable to that of the material, regardless of CA size. Flexural strength reduced gradually from the top to the bottom layer, regardless of CA size, and all of which were lower than the material's true flexural strength. The greatest reduction of 42 % was observed in the bottom layer of UHPC using 1.18 mm CA. The flexural strength decreased with the increase of the CA size. This is attributable to fiber bending and ultimately lower fiber efficiency.

Department(s)

Civil, Architectural and Environmental Engineering

Publication Status

Full Text Access

Comments

Natural Science Foundation of Jiangsu Province, Grant YSZX-01-2022-02-B

Keywords and Phrases

Coarse aggregate; Compressive strength; Flexural strength; Stability; UHPC

International Standard Serial Number (ISSN)

1359-8368

Document Type

Article - Journal

Document Version

Citation

File Type

text

Language(s)

English

Rights

© 2025 Elsevier, All rights reserved.

Publication Date

15 May 2025

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