Details:

Creators:
Ghorbanpoor, Al ; Madathanapalli, S.C.
Ghorbanpoor, Al ; Madathanapalli, S.C. Less -
Corporate Creators:
University of Wisconsin--Milwaukee. Dept. of Civil Engineering and Mechanics
Contributors:
Virmani, Y. Paul
Corporate Contributors:
United States. Federal Highway Administration. Office of Engineering and Highway Operations R&D
Subject/TRT Terms:
[+]
Cement Grouts Concrete Bridges Grouting Posttensioning
Publication/ Report Number:
FHWA-RD-92-095
Resource Type:
Tech Report
Geographical Coverage:
United States
Edition:
Final Report
Contracting Officer:
Virmani, Y.P.
Corporate Publisher:
United States. Federal Highway Administration. Office of Engineering and Highway Operations R&D
Abstract:
Selection of an appropriate grout mix for filling the ducts of post-tensioned bridge structural elements is an important task that could provide long-term protection of post-tensioning steel against corrosion. Important properties of a suitable grout mix include its workability, protection against corrosion of steel, low permeability, ability to expand, high compressive strength, ability to bond to the steel and duct, and overall durability. To identify the most appropriate grout mix for the post-tensioning application, a test program was carried out in this study to evaluate 15 different grout mixes that had shown promise based on an evaluation of existing literature and data. .These mixes included pozzolanic materials, i.e., portland cement and commercially available grouting admixtures. For each grout, several properties were determined. The findings included results on the expansion and shrinkage, bleeding characteristics, compressive strength, flow time, permeability, pH of bleed water, setting time, and surface corrosion observations of the post-tensioning steel surrounded by each mix. As a result of the study, it was determined that the most appropriate mix for the post-tensioning application consisted of type I portland cement, 20 to 25 percent silicafume by the weight of cement, potable water, and a superplasticizer. Other than a slight shrinkage of this mix, the grout showed a superior performance with regard to the properties that were determined through this laboratory testing. If a small dosage of an expansive agent can be added to the mix without adverse effect, the slight shrinkage of the mix may be overcome readily. Most grouts that are used for grouting of post-tensioning ducts exhibit thixotropic property and therefore, the present ASTM Standard Flow Cone Test cannot be used to determine the flowability of the mixes. New test apparatus and procedures were designed and developed during this study that permit quantitative measurement of the flowability of all mixes, including those with thixotropic characteristics. The test procedure includes measuring time of flow, or discharge, for a mix that is placed in a pressure chamber and is forced to pass through a special orifice.
Format:
PDF
Funding:
DTFH61-89-C-00008
Collection(s):
Federal Highway Administration
Main Document Checksum:
[+]
urn:sha256:89f5a3d144d476514898223e85bb1de1caa89af758cf1c55d3c62237a1dbc70b
Download URL:
https://rosap.ntl.bts.gov/view/dot/66660/dot_66660_DS1.pdf
File Type:

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