Contribution of Shrinkage-Reducing Admixture and Lightweight Sand to Moist-Curing Requirement for Fiber-Reinforced Ultra-High-Performance Concrete

Abstract

This study evaluates the potential to use shrinkage-reducing admixture (SRA) and pre-saturated lightweight sand (LWS) to shorten the external moist-curing requirement of ultra-high-performance concrete (UHPC), which is critical in some applications where continuous moist-curing is challenging. Key characteristics of UHPC prepared with and without SRA and LWS and under 3 days, 7 days, and continuous moist curing were investigated. Results indicate that the combined incorporation of 1% SRA and 17% LWS can shorten the required moist-curing duration because such a mixture under 3 days of moist curing exhibited low total shrinkage of 360 µε and compressive strength of 135 MPa (19,580 psi) at 56 days, and flexural strength of 18 MPa (2610 psi) at 28 days. This mixture subjected to 3 days of moist curing had a similar hydration degree and 25% lower capillary porosity in paste compared to the Reference UHPC prepared without any SRA and LWS and under continuous moist curing. The incorporation of 17% LWS promoted cement hydration and silica fume pozzolanic reaction to a degree similar to extending the moist-curing duration from 3 to 28 days and offsetting the impact of SRA on reducing cement hydration. The lower capillary porosity in the paste compensated for the porosity induced by porous LWS to secure an acceptable level of total porosity of UHPC.

Department(s)

Civil, Architectural and Environmental Engineering

Comments

Missouri Department of Transportation, Grant TR2021-21

Keywords and Phrases

lightweight sand (LWS); moist-curing duration; shrinkage-reducing admixture (SRA); ultra-high-performance concrete (UHPC)

International Standard Serial Number (ISSN)

0889-325X

Document Type

Article - Journal

Document Version

Citation

File Type

text

Language(s)

English

Rights

© 2024 American Concrete Institute, All rights reserved.

Publication Date

01 Jan 2024

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