## 3 Results
Thus, the higher the resolution, the lower the likely range of variation in the composition of the specimen studied around the values estimated from the analysis of its core with the method developed. It is important to emphasize that even in the ideal case of null imprecision of the method of analysis of the core, there will be a difference between the estimates and the reference values due to the compositional difference between the core and the specimen, such that the ideal resolution does not imply the absence of uncertainties. To compare the estimates with the references, it is necessary to establish a relative measurement that considers the difference in absolute value between the estimate and its reference in relation to the reference value. According to this, we define the mean absolute \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline  & \multicolumn{2}{c}{**Estimated (\%)**} & \multicolumn{3}{c}{**Reference (\%)**} \\ \cline{2-7}
**Probe** & **Pore** & **EVA 1** & **Gravel 1** & **Pore** & **EVA** & **Gravel** \\ \hline CR & 2.630 & 3.50 & 33.45 & 5.410 & 0.000 & 44.16 \\ EF5 & 5.710 & 4.860 & 41.22 & 5.950 & 2.220 & 41.95 \\ EF15 & 7.830 & 7.280 & 32.46 & 8.980 & 6.590 & 37.55 \\ EF25 & 10.57 & 9.460 & 30.76 & 12.31 & 11.04 & 33.12 \\ EG15 & 7.130 & 4.520 & 43.06 & 11.21 & 6.650 & 37.53 \\
1 EF5 & 1.340 & 2.710 & 43.78 & 0.860 & 2.220 & 41.54 \\
1 EF15 & 16.54 & 8.580 & 37.58 & 15.28 & 6.590 & 37.18 \\
1 EF25 & 12.56 & 9.110 & 26.96 & 10.39 & 11.04 & 32.80 \\
1 EG15 & 6.000 & 6.495 & 43.01 & 7.200 & 6.650 & 37.16 \\ \hline \hline \end{tabular} \({}^{\dagger}\) Calibrated value.  
\end{table} 
Table 6: Comparison of estimated and reference percentages of pore, EVA, and gravel contents after calibration. Figure 9: Comparison between the calibrated estimates of gravel and EVA and the reference values. percentage difference (MAPD) using the same notation as Equation (10), of the form (the formulation is similar to the mean absolute percentage error (MAPE)). \[MAPD=\frac{100}{n}\sum_{i=1}^{n}\mid\frac{v_{e,i}-v_{r,i}}{v_{r,i}}\mid(\%). \tag{11}\]  
The MAPD calculated for each variable measured in our method is an adequate measure to characterize the quality of our method in the range of variation of the composition of the specimens, that is, with EVA contents ranging between 0% and 25%, fiber content ranging between 0% and 1%, and volumetric gravel content equal to 44.2% for EVA and fiber contents (see Table 2). However, MAPD has a natural limitation, which is that it can only handle cases in which the reference variable is not null, to avoid division by zero. Therefore, the case studies in which \(v_{R}=0\) were not included in the calculation of the mean differences or in the variation of the differences in what follows. That is, this analysis leaves out four (CR, EF5, EF15, EF25, and EG15) of the nine test cases for fiber and one test case (RC) for EVA. Table 7 presents the mean absolute percentage difference (MAPD) between the estimated and reference percentages of the volume of pores, gravel, and EVA, considering the nine samples (except EVA where the reference concrete was not included, leaving only eight samples). The MAPD for fiber was not calculated for the reasons explained above. MAPD varies between 11.3% for the gravel volume and 31.0% for the EVA content, which defines an acceptable range, taking into account that the composition of the cores scanned with Micro-CT can differ significantly from the composition of the specimen from which it was extracted. Establishing a dependence between MAPD and the quality \(Q\) of the estimates, such that \(Q=100-MAPD\), we would have qualities ranging between 69.0% and 88.7%. It is worth highlighting that in this study, we describe the results of the first version of the method, which may be subject to future improvements.