SCEBs - University of Colorado Boulder

Portland cement. The blocks originated from the Crow Tribe. The blocks were tested in
the flat position and completely dry. The Schmidt Hammer rebound value (R) was
recorded at the center of each block. Twelve rebound tests were performed on each block
and the results are presented in Appendix 8.2.2. The eight blocks were then immediately
tested in compression using the 1,000 kip MTS Machine in the Structures Lab provided
by the University of Colorado.
The recorded UCS values were plotted versus the corresponding R values (Figure
5.9). A linear regression analysis was carried out to determine the trend between the two
parameters. This trend can then be used to predict the unconfined compressive strength
of CEB blocks from R measurements conducted in the lab or in the field. It should be
noted that this trend is unique for specific CEB mixtures.
UCS [psi]
4500
4000
3500
3000
2500
2000
1500
1000
500
0
UCS vs Schmidt Hammer Rebound Value "R"
y = 87.973x + 1475.3
R 2 = 0.5637
15 18 21 24 27 30
Schmidt Hammer "R" Value
Data Points
Trend-line
Figure 5.9: UCS Value vs. Schmidt Hammer Rebound Value
The linear regression analysis offers a relatively low R 2 value of 0.56. Although a
trend between the two values can be recognized, the results are not sufficiently correlated
to suggest a strong relationship between Schmidt Hammer rebound and UCS values at
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