# Influence of Waste Filler on the Mechanical Properties and Microstructure of Epoxy Mortar
## 3 Results and Discussion
### Fourier Transform Infrared Spectroscopy (FTIR)  
Figure 8 and Table 2 show the FTIR analysis of C, EP, ES, EM, and ESS. Figure 8A shows the combined analysis of all materials. Figure 8B shows that the characteristic peak intensity of C is the highest in the C\({}_{3}\)S and C\({}_{2}\)S groups at 873 cm\({}^{-1}\), compared to C\({}_{3}\)A with a peak of 1416 cm\({}^{-1}\). Moreover, the band for the portlandite was available at 3426 cm\({}^{-1}\). The chemical functional groups observed in C\({}_{3}\)S and C\({}_{2}\)S contain compounds Si-O-Si and Ca-O-Si, while C\({}_{3}\)A and portlandite contain Al-O, Ca-O-Al, and Ca-O, O-H [40]. The band regarding the I.R. spectrum of EP is seen in Figure 8C briefly at 840 cm\({}^{-1}\) and is assigned to C-Cl stretching vibration; however, C=O stretching vibration occurs at 1650 to 1720 cm\({}^{-1}\). On the other hand, the appearance of the band at around 1247 cm\({}^{-1}\) indicates the rocking of the C-H bonds in the molecule [41]. The quartz peaks corresponding to the stretching vibrations of the Si-O bonds in the ES are typically observed in the region of 1000-1200 cm\({}^{-1}\) (Figure 8D) [42]. However, quartz is hard and can provide additional strength and durability to the ES. In addition, C-H aromatic rings corresponding to a peak at 828 cm\({}^{-1}\) for EM, EP, and ES are identical [43]. Figure 8E shows C-H symmetric and asymmetric deformation corresponding to peaks at 1181 cm\({}^{-1}\); at the same time, the peaks at 1411 cm\({}^{-1}\) are due to Si-O and Ca-O stretching in the EM [44]. It is determined that specific peaks in the FTIR spectrum correlated with improved strength and durability. For ESS, the antisymmetric absorption vibration peaks of Si-O groups appear at 989 cm\({}^{-1}\). These groups are due to the C\({}_{2}\)S and C\({}_{3}\)S phases present in the ESS (Figure 8F) [45]. The antisymmetric absorption vibration peaks of the Fe-O group appear at 859 cm\({}^{-1}\)[46]. Si-O and Fe-O bonds in the FTIR spectrum improve the strength, toughness, and bonding between the epoxy matrix and the steel slag filler. The transmittance bands at 1608 and 1508 cm\({}^{-1}\) are due to the C-C bond of the aromatic ring. The band at 2922 cm\({}^{-1}\) in the FTIR spectrum is due to asymmetric and symmetric stretching interactions of the methyl and methanol [47].  
\begin{table}
\begin{tabular}{c c c c c c c c c} \hline
**Imp. Peaks/ Materials** & **OH** &
\begin{tabular}{c} **C-H str./** \\ **C-H Rock.** \\ \end{tabular} & **C-C** & **C-Cl** & **Si-O** & **Al-O** & **Ca-O** & **Fe-O** \\ \hline
7(B) C (\(\widetilde{\
u}\), cm\({}^{-1}\)) & 3426 & - & 1663 & - & 952 & 1090 & 1416 & 583 \\ \hline
7(C) EP (\(\widetilde{\
u}\), cm\({}^{-1}\)) & 3250 &
\begin{tabular}{c} 2922, 2851/ \\ 1247/828 \\ \end{tabular} & 1608, 1509 & 630, 840 & - & - & - & 585 \\ \hline \end{tabular}
\end{table}
Table 2: Summary of Important Functional Groups (FGs) observed from the FTIR Peaks.  
Figure 7: Water absorption of cement mortar (C), epoxy PVC waste (EP), epoxy sand (ES), epoxy marble dust (EM), and epoxy steel slag (ESS) after 3 days, 7 days, and 14 days of exposure. Data represents mean \(\pm\) standard deviation (indicated by vertical error bars), n = 3.  
Figure 8: FTIR analysis of all fillers (**A**), cement mortar (**B**), epoxy PVC waste (**C**), epoxy sand (**D**), epoxy marble dust (**E**), and epoxy steel slag (**F**).