Details:

Creators:
Rupnow, Tyson D.
Corporate Creators:
Louisiana Transportation Research Center
Corporate Contributors:
Louisiana. Dept. of Transportation and Development
Subject/TRT Terms:
[+]
Fly Ash Heat Heat Generation Quality Assurance Quality Control Set Time Time
Publication/ Report Number:
FHWA/LA.10/469
Resource Type:
Tech Report
Geographical Coverage:
Louisiana
Edition:
Final report; Mar. 2009-June 2010.
Corporate Publisher:
Louisiana Transportation Research Center
NTL Classification:
NTL-HIGHWAY/ROAD TRANSPORTATION-Materials;NTL-HIGHWAY/ROAD TRANSPORTATION-Pavement Management and Performance;
Abstract:
Many entities currently use fly ash in portland cement concrete (PCC) pavements and structures. Although the body of knowledge is great concerning the use of fly ash, several projects per year are subject to poor performance where fly ash is named as the culprit. Generally the “bad” projects arise due to one of two common errors: 1. Poor understanding of what fly ash is and how it affects concrete pavement construction and performance; or, 2. A switch of fly ash sources midstream during the construction project. The objective of this research was to identify tools available for quality control (QC) of as delivered class C fly ash. The main focus of the research was to identify penetration type devices and test procedures including the Iowa Set Time Test, Gillmore needle, and Vicat needle. Another focus of the investigation was the quick heat generation index test. For the first objective, three penetration type test devices were investigated including the Vicat needle, Gillmore needle, and the pocket penetrometer. Class C fly ash samples were obtained from about ten sources available to Louisiana Department of Transportation and Development (LADOTD). The second objective was to indentify if the quick heat generation test can identify small changes in class C fly ash whether that be a change in chemistry or a physical change in the fly ash fineness. Statistical modeling was used to determine if a relationship existed between the various initial and final set times and the maximum temperature of the fly ash paste and the fly ash chemistry and fineness The Gillmore needle, Vicat needle and the pocket penetrometer yielded similar results when observing the times to initial and final set across the three test methods. Although the test methods pointed out significant differences in set times between buckets within a source, those differences were a non-issue when incorporating portland cement into the sample. The temperature results showed that the test method is unable to be used as either a quality control or quality assurance device in characterizing class C fly ash. The statistical analysis results showed outliers within the sources, but further testing when incorporating portland cement showed these differences to be negligible in effect. A suitable correlation was found to exist between the calcium oxide and sulfur trioxide content and the maximum temperature of the fly ash temperature results.
Format:
PDF
Collection(s):
US Transportation Collection
Main Document Checksum:
[+]
urn:sha256:d8e0244a3d2d87e3b6a51f236552f62d82aa10a534bee5d98213db56f164a262
Download URL:
https://rosap.ntl.bts.gov/view/dot/20288/dot_20288_DS1.pdf
File Type:

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