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Title:

Hydration and Early Age Properties of Cement Pastes Modified with Cellulose Nanofibrils

Accession Number:

01751345

Record Type:

Component

Availability:

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Order URL: http://worldcat.org/issn/03611981

Abstract:

In this work, the effects of cellulose nanofibrils (CNFs) on workability, hydration reaction, microstructure, early age shrinkage, fracture properties, flexural strength, and compressive strength of cement paste were investigated. Six batches with variable CNF concentrations with the same water-to-cement (w/c) ratio (0.35) were tested. Flow table test showed a reduction in the workability as CNF dosage increased. Isothermal calorimetry (IC) tests showed that after 3?days, degree of hydration (DOH) improved up to 8% because of the addition of CNFs. Thermogravimetric analysis (TGA) tests at 7 and 28?days showed no significant changes in DOH for all pastes. After 7?days, mixture with 0.15% CNF resulted in up to 31% improvement in compressive strength. For 0.09% CNF addition, cement paste showed 26% increase in compressive strength after 28?days. Tests revealed that adding a small quantity of CNF (0.06%) along with entraining 0.05 extra water reduces autogenous shrinkage by 49% at a cement paste with w/c?=?0.30. For interpreting the results, a tunnels, reservoirs, and bridges (TR&B) model is proposed. This model suggests that, as proposed by others, CNFs can modify microstructure by providing tunnels for transporting water to unhydrated cement grain. Because of their hydrophilicity, CNFs retain water and work as reservoirs (internal curing), which explains the improvement in properties at low w/c ratios. Significant increases in fracture energy (up to 60%) and flexural strength (up to 116%) suggest that CNFs are an effective toughening mechanism, acting as bridges that increase the energy required for crack propagation.

Supplemental Notes:

© National Academy of Sciences: Transportation Research Board 2020.

Language:

English

Authors:

Haddad Kolour, Hosain
Ashraf, Warda
Landis, Eric N

Pagination:

pp 38-46

Publication Date:

2021-9

Serial:

Transportation Research Record: Journal of the Transportation Research Board

Volume: 2675
Issue Number: 9
Publisher: Sage Publications, Incorporated
ISSN: 0361-1981
EISSN: 2169-4052
Serial URL: http://journals.sagepub.com/home/trr

Media Type:

Web

Features:

References (38)

Subject Areas:

Highways; Materials

Files:

TRIS, TRB, ATRI

Created Date:

Aug 29 2020 3:04PM