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Ultra-High Performance Concrete Overlay Behavior and Bond Characterization.

Record Type:	Language materials, manuscript : Monograph/item
Title/Author:	Ultra-High Performance Concrete Overlay Behavior and Bond Characterization./
Author:	Toledo, William K.
Description:	1 online resource (302 pages)
Notes:	Source: Dissertations Abstracts International, Volume: 85-03, Section: A.
Contained By:	Dissertations Abstracts International85-03A.
Subject:	Civil engineering. -
Online resource:	click for full text (PQDT)
ISBN:	9798380166126

Ultra-High Performance Concrete Overlay Behavior and Bond Characterization.
Toledo, William K.

Ultra-High Performance Concrete Overlay Behavior and Bond Characterization. - 1 online resource (302 pages)

Source: Dissertations Abstracts International, Volume: 85-03, Section: A.

Thesis (Ph.D.)--New Mexico State University, 2023.

Includes bibliographical references

The work presented in this dissertation investigates the behavior and bond characterization of an ultra-high performance concrete (UHPC) overlay. This study stemmed from research that focused on assessing a non-proprietary UHPC for use as an overlay to rehabilitate deteriorated concrete bridge decks. This assessment began by characterizing the concrete materials used in this study that consisted of a normal strength concrete (NSC) as the substrate material and UHPC as the overlay material.The effectiveness of an overlay material greatly depends on its ability to bond to the existing substrate. Therefore, bond performance of composite specimens that consisted of NSC substrate overlaid with an UHPC overlay was investigated. Overlay bond was assessed by using bond tests that included slant-shear and direct shear tests to characterize shear strength and indirect and direct tension tests to characterize tensile strength.This work also includes finite element models (FEMs) developed to simulate the effects of thermal movements of UHPC relative to NSC substrate. These models were used to assess bond stresses developed from thermal loading on a UHPC overlaid bridge deck. Furthermore, FEMs of full-scale two-span bridges with three span lengths were developed to simulate effects of thermal loading on UHPC-overlaid bridge decks.Results from the bond assessment tests revealed that UHPC overlay bond depended on substrate surface preparation. Substrate surface preparation included surface texture and surface moisture condition prior to overlay placement. The slant-shear specimens had shear strengths that ranged from 1032 psi (7.1 MPa) to 2874 psi (19.8 MPa) for substrate surface textures from lightly ground to rough, respectively. Direct shear strengths achieved for specimens with sandblasted surface textures from brush to heavy were 210 psi (1.45 MPa) to 453 psi (3.12 MPa) that had saturated surfaces prior to UHPC placement. Adequate bond strength for shear was characterized by substrate failures that were observed for shear strengths greater than 145 psi (1.00 MPa) during direct shear tests. Indirect tension tests yielded tensile strengths of 254 psi (1.8 MPa) to 351 psi (2.4 MPa) for split-cylinder and 225 psi (1.5 MPa) to 538 psi (3.7 MPa) for split-prism specimens with lightly ground to rough surface textures, respectively. Using sandblasted surface textures, direct tensile strengths 235 psi (1.62 MPa) to 327 psi (2.25 MPa) were achieved for specimens with a brush sandblasted to heavy sandblasted surfaces, respectively. Specific conclusions drawn from the bond assessment studies were that to achieve adequate bond, the substrate surface texture should remove cement paste to expose aggregates and have a visibly moist surface prior to placing the UHPC overlay.UHPC thermal and shrinkage properties were investigated because incompatibilities between the overlay and substrate materials can cause stresses that will affect bond performance Thermal and shrinkage characterization of overlaid specimens was performed using shrinkage and coefficient of thermal expansion tests.The UHPC overlay material had a total shrinkage of 851 µstrain which is less than the 1000 µstrain maximum shrinkage limit specified by many state departments of transportation. UHPC had a coefficient of thermal expansion value of 10.8 µ/°F (19.5 µ/°C) which is about 95% greater than what would be commonly expected for NSC (typically near 5.5 µ/°F [10 µ/°C]). This indicates that the thermal movements of the UHPC overlay will be substantially greater than the substrate concrete that will typically have a lower coefficient of thermal expansion and also experience smaller temperature swings.Stress results from finite element analyses of three full-scale bridge decks that had two spans measuring 60, 120, and 240 ft. (18.3, 36.6, and 73.2 m) were compared with laboratory bond strength test results. Finite element results showed that the overall maximum bond tensile and shear stresses were 965 psi (6.65 MPa) and 9790 psi (12.3 MPa) from thermal loading and shrinkage induced stresses for the 120 and 240 ft. (36.6 and 73.2 m) spanned bridges, respectively. The models showed that there were large compressive and shear bond stresses induced from shrinkage but did not compensate for overlay cracking. After analyzing overlay cracking, it was recommended to install construction joints at 12 ft (3.66 m) spacings in both the longitudinal and transverse directions of the bridge.The results from this study have reinforced the notion that UHPC can be a viable candidate for use as an overlay material. The results obtained from this study were impactful since the surface preparation methods on a majority of the laboratory specimens only satisfied the minimum requirements to achieve adequate bond strengths.

Electronic reproduction.
Ann Arbor, Mich. :
ProQuest,
2024

Mode of access: World Wide Web

ISBN: 9798380166126Subjects--Topical Terms:

561339
Civil engineering.
Subjects--Index Terms:

Bond strengthIndex Terms--Genre/Form:

554714
Electronic books.

Ultra-High Performance Concrete Overlay Behavior and Bond Characterization.
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653 $a Finite element models
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710 2 $a New Mexico State University. $b Civil Engineering. $3 1465470
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