|
MINDS @ UW >
MINDS@UW Madison >
College of Engineering, University of Wisconsin--Madison >
Department of Civil and Environmental Engineering >
Master's Theses--Civil Engineering >
Please use this identifier to cite or link to this item:
http://digital.library.wisc.edu/1793/6583
|
| Title: | The effects of aggregate coatings on the performance of Portland cement concrete |
| Authors: | Gullerud, Karl J. |
| Keywords: | Thesis (M.S.)--University of Wisconsin--Madison, 2002.
Dissertations, Academic Civil and Environmental Engineering.
University of Wisconsin--Madison. College of Engineering. |
| Issue Date: | 2002 |
| Publisher: | University of Wisconsin-Madison |
| Abstract: | Specifications which limit the amount of fine material that adheres to coarse
aggregates tend to be vague. For example, the Wisconsin state specifications require coarse
aggregates used in portland cement concrete to be free of deleterious substances and adherent
coatings; however, neither the washing procedure nor the desired end result of aggregate
washing is specified. The purpose of this research was to identify which aggregate coatings
in Wisconsin are deleterious and to determine what degree they affect concrete durability and
strength. To this end, coarse aggregates containing surface coatings were collected
throughout the state and characterized with the California cleanness test, methylene blue
adsorption test, and x-ray diffraction. Based on the results of these tests, a subset of the
sampled aggregates was selected to further study the effects of the coatings on concrete
performance. It was hypothesized that coatings containing clay material are more deleterious
than coatings containing either dust or carbonate material.
The 10-batch mixing plan tested coarse aggregates fiom three different sources and in
the following three conditions: (1) coated aggregates that were sampled in the field, (2)
washed aggregates that were washed in the laboratory to remove the existing coating, and (3)
coated aggregates that were manufactured with dust and clay fines to increase the extent of
the coating. The effect of each aggregate coating on concrete performance was assessed by
comparing the relative changes in compressive strength, tensile strength, drying shrinkage,
freeze-thaw durability, and chloride ion penetrability between batches containing the washed and coated aggregates. The test results confirmed that coatings with high clay contents are more deleterious to concrete strength and durability than coatings that consist largely of dust or carbonate material. While the carbonate coatings appeared to slightly improve performance, the clay coatings appeared to significantly decrease strength and durability. Although current washing procedures do not need to be changed, it was recommended that the WisDOT require the California cleanness test whenever aggregate coatings are suspected of influencing strength or durability during concrete construction. |
| Description: | Under the supervision of Professor Steven Cramer; Pages: 168. |
| URI: | http://digital.library.wisc.edu/1793/6583 |
| Appears in Collections: | Master's Theses--Civil Engineering
|
Files in This Item:
| File |
Description |
Size | Format | Handle |
|---|
| Gullerud2002.pdf | | 4148Kb | Adobe PDF | http://digital.library.wisc.edu/1793/6584 | View/Open |
|
Items in DSpace are protected by copyright, with all rights reserved, unless otherwise indicated.
|
