## 2 Materials and Methods  
The performance of self-compacting mortars was evaluated using published datasets, which were collected during the authors' previous experimental studies [41].  
The mortar specimens were produced using CEM I 42.5 R cement, limestone filler, normalized sand, and a polycarbonate-based superplasticizer. The cement was purchased from Secil Portugal (Outao, Portugal) and was compliant with EN 197-1 specifications. Limestone filler with specific gravity of 2.68 g/cm\({}^{3}\) was provided by Omya S.A under the commercial reference of Betocarb 10 HP--OU. Normalized sand compliant with EN 196-1 was used in all experiments, with a water absorption of 0.30% and specific gravity of 2.63 g/cm\({}^{3}\). The selected superplasticizer (ViscoCrete(r)-20 HE, from SIKA, Vila Nova de Gaia, Portugal) was characterized by a density of 1.08 g/cm\({}^{3}\) and a solid content of 40%.  
The dataset includes a total of thirty formulations of self-compacting mortars with four quantitative input variables. A central composite design was defined using Design-Expert software (Stat-Ease, Inc., Minneapolis, MN 55413-2561, USA--Design--Expert(r) Software, version 13.0.9.0 64-bit; Serial Number 0964-0841-3719-3394) consisting of a factorial design of four factors in two levels (2\({}^{4}\)) representing 8 axial and 6 central realizations. The four input variables analyzed included the following--A: water-to-cement ratio (w/c); B: superplasticizer-to-powder (CEM I 42.5 R + limestone filler) ratio (Sp/p); C: water-to-powder (CEM I 42.5 R + limestone filler) ratio (w/p); and D: sand-to-mortar ratio (s/m). All ratios refer to volumetric relations. The evaluation levels were \(-\infty\), \(-1\), \(0\), \(+1\), and \(+\infty\), with \(\infty\) being equal to 2. Table 1 shows the relation between coded points and real values.  
Workability and strength development were evaluated as outputs. Four response variables were defined and examined, namely, these included the following: Y1: D-Flow results (in mm); Y2: T-Funnel (in seconds); and compressive strength measured after 1 and 28 days of curing (Y3 and Y4, respectively, both expressed in MPa). The D-Flow and T-Funnel testing were conducted following EFNARC specifications and guidelines for self-compacting concrete, whereas compressive strength was determined as per EN 196-1. The detailed description of the testing protocols can be found elsewhere [41]. For compressive strength measurements, a minimum of four specimens was tested with respect to formulation and curing age. The average strength values were considered representative, and only those values are reported here. All experiments have been conducted in randomized order. Table 2 shows the coded input values (A-D) and the average result of each individual response (Y1-Y4).  
\begin{table}
\begin{tabular}{c c c c c} \hline
**Levels** & **A: w/c** & **B: Sp/p** & **C: w/p** & **D: s/m** \\ \hline \(-2\) & 0.78741 & 0.02069 & 0.46929 & 0.42240 \\ \(-1\) & 0.84110 & 0.02210 & 0.50129 & 0.45120 \\ \(0\) & 0.89478 & 0.02351 & 0.53328 & 0.48000 \\ +1 & 0.94847 & 0.02492 & 0.56528 & 0.50880 \\ +2 & 1.00216 & 0.02633 & 0.59728 & 0.53760 \\ \hline \end{tabular}
\end{table}
Table 1: Equivalence of coded and real values (reproduced from [41]).