# Uniaxial Testing of Soil-Cement Composites to Obtain Correlations to Be Used in Numerical Modeling
## 4 Laboratory Test Results and Discussion of the Obtained Results
### Testing of Laboratory Made Samples
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Time of Curing Days** & **Density g/cm\({}^{3}\)** & **Compressive Strength kPa** & **Critical Deformation \%** & **Elastic Modulus MPa** \\ \hline
3 & 1.840 & 256.01 & 2.0 & 27.584 \\
7 & 1.782 & 355.71 & 1.6 & 10.761 \\
14 & 1.796 & 285.14 & 1.5 & 29.323 \\
28 & 1.725 & 385.16 & 2.7 & 12.89 \\
56 & 1.534 & 995.46 & 1.2 & 116.987 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Averaged values of Type II reference tests. Figure 9: A dependency between elastic modulus and the compressive strength of the composite. It must be underlined again that the presented values are the averaged values from four samples tested within each time period. So, one may suspect some clearly visible trends. The trends indeed confirm common sense and engineering judgement, but the large number of outliers (not filtered) bring some unexpected results. The authors of the study could remove the results that do not fit the theory, but it seems that caution about possible discrepancies is a bigger value (considering soil-cement composites and their reliability) than just confirming well-known facts, especially when we understand that laboratory-made samples were mixed in a more controlled way than the material in the \"in situ\"-produced column. That is why laboratory production and testing of trial composites are believed to deliver \"upper bound\" results in compressive strength and elastic modulus. Another problem of major importance is the optimal time for curing. From the figures given below (Figures 10-12), we may observe that all the measured values are highly time-dependent. The composite density in Figure 10 decreases slowly in the second month of curing. Changes in compressive strength (Figure 11) and elastic modulus (Figure 12) seem to be far more significant and prove the necessity to prolong the curing times of DSM samples up to two or even three months to gain valuable and reliable information. No trendline was provided in Figures 11 and 12, just so as not to be misleading. One may observe that increasing with time values of R\({}_{\text{c}}\) and E should still be considered with cautious attention due to the simultaneously increasing standard deviation of the gathered results. \begin{table}
\begin{tabular}{c c c c c} \hline
**Time of Curing** & **Density** & **Compressive Strength** & **Critical Deformation** & **Elastic Modulus** \\
**Days** & **g/cm\({}^{3}\)** & **kPa** & **\%** & **MPa** \\ \hline
3 & 1.720 & 158.43 & 4.3 & 7.131 \\
7 & 1.724 & 133.45 & 5.6 & 7.117 \\
14 & 1.764 & 154.74 & 2.6 & 7.030 \\
28 & 1.674 & 215.22 & 4.9 & 6.560 \\
56 & 1.474 & 407.57 & 4.6 & 9.193 \\ \hline \end{tabular} \[\text{E}=118\times\text{R}_{\text{c}}-2.03\text{ [MPa]},\] (4)  
\end{table} 
Table 4: Averaged values of Type III reference tests. Figure 10: Composite density decreasing in time domain. \begin{table}
\begin{tabular}{c c c c c} \hline
**Time of Curing** & **Density** & **Compressive Strength** & **Critical Deformation** & **Elastic Modulus** \\
**Days** & **g/cm\({}^{3}\)** & **kPa** & **\%** & **MPa** \\ \hline
3 & 1.698 & 155.59 & 2.6 & 9.377 \\
7 & 1.714 & 192.03 & 1.6 & 29.424 \\
14 & 1.743 & 179.63 & 2.3 & 25.155 \\
28 & 1.658 & 208.71 & 3.9 & 15.182 \\
56 & 1.430 & 398.85 & 2.5 & 44.846 \\ \hline \end{tabular}
\end{table} 
Table 5: Averaged values of Type IV reference tests. The results of the reference tests presented above formed the basis for the evaluation of the samples taken directly from DSM columns formed in the test field.