Materials selection for concrete overlays : the final report Page: 75
xviii, 192 p. : col. ill. ; 28 cm.View a full description of this report.
Extracted Text
The following text was automatically extracted from the image on this page using optical character recognition software:
Table 4.5: Compressive Strength Results
7 days (psi) 28 days (psi)
Mixture
No. Average Average
1 5538 7590
2 3526 5798
3 5302 6238
4 3554 5721
5 6632 7909
6 3744 6128
7 6871 8017
8 3285 5837
9 5286 9149
10 5263 7196
11 4568 6294
12 5983 7501
13 3738 6058
14 5153 6929
15 5254 7359
16 5065 6960
17 6116 7888Based on the statistical analysis, it was determined that the 7-day compressive strength
was most affected by the following variables: SCM content, sacks of cement, SCM
content*SCM content, and SCM content*sacks of cement. SCM content*SCM content and SCM
content*sacks of cements are second order effects. If a second order effects is significant, then
the regression model for the compressive strength will display curvature (as shown Figure 5.6).
(Note, the second order effect of SCM content*SCM content can also be written as (SCM
Content)2. This yielded the following regression model (in coded units):
7-day compressive strength 5243 -1248 SCM content + 366 sacks of cement-
426 (SCM content)2 -339 SCM content*sacks of cement and R2 = 95%. (4-3)
From the regression equation, it can be seen that 7-day compressive strength is most
influenced by the SCM content. A unit change in the SCM content affected the 7-day
compressive strength more than a unit change in the sacks of cement. Increasing the SCM
content significantly reduced the compressive strength, whereas the compressive strength
increased when the sacks of cement increased. In general, increasing the fine aggregate ratio
decreased the compressive strength, but in the range used, the change in the compressive strength
was not found to be significantly influenced.
With regards to the 28-day strength, the value for Mixture 9 appeared to be an outlier.
Thus this value was ignored in the analysis. It was determined that the 28-day compressive
strength was most affected by the following variables: SCM content and sacks of cement. This
yielded the following regression model (in coded units):75
Upcoming Pages
Here’s what’s next.
Search Inside
This report can be searched. Note: Results may vary based on the legibility of text within the document.
Tools / Downloads
Get a copy of this page or view the extracted text.
Citing and Sharing
Basic information for referencing this web page. We also provide extended guidance on usage rights, references, copying or embedding.
Reference the current page of this Report.
Kim, Dong H.; Fowler, David W.; Ferron, Raissa P.; Trevino, Manuel M. & Whitney, David P. Materials selection for concrete overlays : the final report, report, July 2012; Austin, Texas. (https://texashistory.unt.edu/ark:/67531/metapth303706/m1/95/: accessed July 17, 2024), University of North Texas Libraries, The Portal to Texas History, https://texashistory.unt.edu.; crediting UNT Libraries Government Documents Department.