Doctoral Dissertations

Abstract

"The main objective of this research is to develop a cost-effective ultra-high performance concrete (UHPC) for bonded bridge deck overlays. The high durability and mechanical properties of such repair material can offer shorter traffic closures and prolong the service life of the pavement. The UHPC was optimized using supplementary cementitious materials (SCMs), proper combinations of sands, and adequate selection of fiber types and contents. Packing density studies included paste, sand, and fiber combinations. The robustness of optimized UHPC mixtures to variations of mixing and curing temperatures was examined. The efficiency of various shrinkage mitigation approaches in reducing autogenous and drying shrinkage of optimized UHPC mixtures was evaluated. This included the use of CaO-based and MgO-based expansive agents, shrinkage-reducing admixture, and pre-saturated lightweight sand. Optimized UHPC mixtures were cast as thin bonded overlays of 25, 38, and 50 mm in thickness over pavement sections measuring 1 × 2.5 m². Early-age and long-term deformation caused by concrete, humidity and temperature gradients, as well as cracking and delamination were monitored over time. Test results indicate that the designed UHPC mixtures exhibited relatively low autogenous shrinkage and drying shrinkage. The G50 mixture had the lowest autogenous and drying shrinkage of 255 µm/m at 28 days and 55 µm/m at 98 days, respectively. All tested UHPC mixtures exhibited a high mechanical properties and excellent frost durability. The use of 60% lightweight sand led to significantly reduction in autogenous shrinkage from 530 to 35 µm/m. Test results indicate that there was no surface cracking or delamination in UHPC overlays after 100 days of casting"--Abstract, page iii.

Advisor(s)

Khayat, Kamal

Committee Member(s)

Chen, Genda
ElGawady, Mohamed
Ma, Hongyan
Chandrashekhara, K.

Department(s)

Civil, Architectural and Environmental Engineering

Degree Name

Ph. D. in Civil Engineering

Sponsor(s)

Missouri. Department of Transportation
Missouri University of Science and Technology. RE-CAST Tier-1 University Transportation Center
Missouri University of Science and Technology. Center for Infrastructure Engineering Studies

Publisher

Missouri University of Science and Technology

Publication Date

Fall 2017

Pagination

xiv, 152 pages

Note about bibliography

Includes bibliographic references (pages 140-151).

Rights

© 2017 Mahdi Valipour, All rights reserved.

Document Type

Dissertation - Open Access

File Type

text

Language

English

Thesis Number

T 11243

Electronic OCLC #

1021857668

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