## 3 Results
### MIX-Fixed-W/C  
#### 3.2.1 ReCiPe2016 Midpoint  
Pairwise comparisons between CBA0, CBA25, CBA50, CBA75, and CBA100 exhibited a gradual increase in the impacts of GWP, TE, FRS, and WC, as shown in Figure 5. According to the analysis of three impacts, i.e., GWP, TE, and WC, there were two multidirectional and responsible factors: Sand production and the transportation of CBA from the coal-fired power plant to the local cement plant, the magnitudes of the influences of which were similar. However, from CBA0 to CBA100, the 28-day concrete's compressive strength decreased considerably from 56 to 32 MPa, as shown in  
Figure 4: Environmental damage caused by replacing sand with coal bottom ash (CBA): A—CBA0, B—CBA25, C—CBA50, D—CBA75, and E—CBA100. The life-cycle assessments (LCAs) were evaluated via the six methodological options of the ReCiPe2016 single-score method: Individualist/average (I/A) hierarchist/average (H/A), egalitarian/average (E/A), individuals/individualist (I/I), hierarchist/hierarchist (H/H), and egalitarian/egalitarian (E/E). The concrete mixtures were designed with a fixed slump range of 60–80 mm. The FU was normalized by dividing the environmental assessment of 1 m\({}^{3}\) of concrete according to the 28-day concrete compressive strength.  
Table 2. The decrease in the 28-day compressive strength of concrete led to an increase in GWP, TE, WC, and FRS when the FU was normalized to the 28-day concrete compressive strength. The combination of the unidirectional responsible factors due to the transition from CBA0 to CBA100, the decreased 28-day compressive strength of the concrete, and the transportation of CBA from the coal-fired power plant to the local cement plant led to a significant increase in the impact of FRS.  
Figure 5: Replacing sand with coal bottom ash (CBA): A—CBA0, B—CBA25, C—CBA50, D—CBA75, and E—CBA100. The environmental impacts were evaluated following the ReCiPe2016 midpoint H method. The concrete mixtures were designed with a fixed W/C of 0.52. The functional unit (FU) was normalized by dividing the environmental assessment of 1 m\({}^{3}\) of concrete according to the 28-day concrete compressive strength.  
\begin{table}
\begin{tabular}{c c c c c} \hline
**Concrete** & **CBA0** & **CBA25** & **CBA50** & **CBA75** & **CBA100** \\ \hline CBA0 & X & 0.1632 & _0.0251_ & **0.0142** & **0.0107** \\ CBA25 & & X & _0.0325_ & **0.0137** & **0.0104** \\ CBA50 & & & X & 0.4137 & _0.0904_ \\ CBA75 & & & X & 0.1203 \\ CBA100 & & & & X \\ \hline \end{tabular} Note: A—CBA0, B—CBA25, C—CBA50, D—CBA75, and E—CBA100. The LCAs were evaluated via the six ReCiPe2016 single score methodological options (I/A, H/A, E/A, I/I, H/H, and E/E). The \(p\)-values were evaluated according to three-valued logic: Bold font—appears to be positive, ordinal font size—appears to be negative, italic font—judgment is suspended.  
\end{table}
Table 4: \(p\)-values (\(p\)) of the paired differences in the life-cycle assessment (LCA) production stage of 1 m\({}^{3}\) of concrete normalized according to the 28-day concrete compressive strength for the five concrete alternatives where sand was replaced with coal bottom ash (CBA). The concrete mixtures were designed with fixed a slump range of 60–80 mm.