Title:
Contribution of Shrinkage-Reducing Admixture and Lightweight Sand to Moist-Curing Requirement for Fiber- Reinforced Ultra-High-Performance Concrete
Author(s):
Le Teng, Alfred Addai-Nimoh, and Kamal H. Khayat
Publication:
Materials Journal
Volume:
121
Issue:
3
Appears on pages(s):
69-80
Keywords:
lightweight sand (LWS); moist-curing duration; shrinkagereducing admixture (SRA); ultra-high-performance concrete (UHPC)
DOI:
10.14359/51740566
Date:
5/1/2024
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.