Abstract
Thin bonded ultra-high-performance concrete (UHPC) overlay is an advanced technology for bridge deck rehabilitation. UHPC should be tailored to secure adequate flowability and high thixotropy to facilitate mixing and placement with a low risk of sagging of the material on sloped bridge deck surfaces. The synergetic effect between nano clay (NC) and polycarboxylate ether (PCE) superplasticizer or cellulose-based viscosity modifying admixture (VMA) and PCE on the rheological properties (yield stress, plastic viscosity, and thixotropy), cement hydration, autogenous shrinkage, compressive strength, and porosity was systematically investigated. The bond strength between conventional concrete (CC) representing existing bridge deck concrete and thixotropic UHPC and the flexural performance of UHPC-CC composite beams were determined. Test results indicate that the incorporation of 1% cellulose based VMA combined with 0.4% PCE can increase thixotropy from 12 to 60 Pa/min when the initial fluidity of the mortar phase of the UHPC was maintained at 200 mm. Such increase was limited to 19 Pa/min in mixtures prepared with 1% NC and 1.55% PCE. The thixotropic UHPC containing NC and cellulose based VMA provided tensile bond strength higher than 3 MPa. The combination of NC and PCE improved the flexural toughness and strength by up to 45% and 30%, respectively, for composite beam specimens. It also led to slightly higher compressive strength associated with greater cement hydration and decreased porosity. The combined use of cellulose based VMA and PCE led to 15% and 40% greater flexural strength and toughness, respectively, despite the 10% lower compressive strength due to a 30% increase in the volume of pores with diameters larger than 5 µm.
Recommended Citation
L. Teng et al., "Synergetic Effect Of Viscosity Modifying Admixtures And Polycarboxylate Ether Superplasticizer On Key Characteristics Of Thixotropic UHPC For Bonded Bridge Deck Overlay Rehabilitation," Case Studies in Construction Materials, vol. 20, article no. e02739, Elsevier, Jul 2024.
The definitive version is available at https://doi.org/10.1016/j.cscm.2023.e02739
Department(s)
Civil, Architectural and Environmental Engineering
Keywords and Phrases
Bond strength; Bridge deck overlay; Cellulose-based viscosity-modifying admixture; Nanoclay; Thixotropy; Ultra-high-performance concrete
International Standard Serial Number (ISSN)
2214-5095
Document Type
Article - Journal
Document Version
Citation
File Type
text
Language(s)
English
Rights
© 2023 Elseiver, All rights reserved.
Publication Date
01 Jul 2024
Comments
National Natural Science Foundation of China, Grant 52308239