## 2 Materials and Methods
### Characterising the Superplasticizers  
The SPs used for this project were named SP-A and SP-B, and are two PCE polymers used for multiple applications in industry. Both SPs were prepared by radical polymerization and are based on Methacrylic acid MPEG-Methacrylate. The molecular weights of the two polymers as received from the suppliers are as follows: \begin{table}
\begin{tabular}{l l l l} \hline \hline \multirow{2}{*}{**Chemical Oxides (\%)**} & \multicolumn{2}{c}{**Cement**} & \\ \cline{2-4}  & **Cement 1** & **Cement 2** & **Cement 3** \\ \hline SiO\({}_{2}\) & 22.6 & 19.9 & 20.2 \\ Al\({}_{2}\)O\({}_{3}\) & 3.07 & 4.14 & 4.47 \\ Fe\({}_{2}\)O\({}_{3}\) & 4.83 & 2.89 & 3.06 \\ Mn\({}_{2}\)O\({}_{3}\) & 0.09 & 0.06 & 0.67 \\ TiO\({}_{2}\) & 0.39 & 0.24 & 0.28 \\ CaO & 63.46 & 65.66 & 63.72 \\ MgO & 1.52 & 0.90 & 2.62 \\ P\({}_{2}\)O\({}_{5}\) & 0.08 & 0.12 & 0.05 \\ SO\({}_{3}\) & 2.51 & 2.46 & 3.53 \\ Cl & 0.00 & 0.00 & 0.00 \\ K\({}_{2}\)O & 0.49 & 0.70 & 0.22 \\ Na\({}_{2}\)O & 0.28 & 0.16 & 0.06 \\ LOI & 1.45 & 3.05 & 1.99 \\ Total & 100.8 & 100.3 & 100.9 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Chemical Analysis of the cements used. \begin{table}
\begin{tabular}{l l l l} \hline \hline \multirow{2}{*}{**Physical Testing**} & \multicolumn{2}{c}{**Cement**} & \\ \cline{2-4}  & **Cement 1** & **Cement 2** & **Cement 3** \\ \hline Relative Density & 3.09 & 3.15 & 3.12 \\ Specific Surface, cm\({}^{2}\)/g & 3800 & 4300 & 4100 \\ Standard Consistency, \% & 28.0 & 27.6 & 28.0 \\ Initial Set Min & 180 & 130 & 100 \\ Final Set Min & 195 & 150 & 120 \\
32 \(\upmu\)m Residue, \% & 15.6 & 23.2 & 9.5 \\
45 \(\upmu\)m Residue, \% & 5.3 & 10.3 & 2.2 \\
90 \(\upmu\)m Residue, \% & 0.2 & 0.8 & 0.1 \\
212 \(\upmu\)m Residue, \% & 0.0 & 0.1 & 0.0 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Physical properties of the cement used. \begin{table}
\begin{tabular}{l l l} \hline \hline \multirow{2}{*}{**Characteristics**} & **SP-A** & **SP-B** \\ \hline Consistency & Liquid & Liquid \\ Color & Amber & Amber \\ Density according to ISO 758 (g/cm\({}^{3}\)) & 1.08 \(\pm\) 0.02 & 1.07 \(\pm\) 0.02 \\ Dry content according to EN 480-8 (\%) & 30.5 \(\pm\) 1.5 & 30 \(\pm\) 1.5 \\ Chlorides soluble in water according to EN 480-10 (\%) & \textless\text{0.1} & \textless{0.1} \\ Alkali content (Na\({}_{2}\)O equivalent) according to EN 480-12 (\%) & \textless{3} & \textless{2.5} \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Characteristics of Superplasticizer. * SP-A = 42,000 (g/mol)
* SP-B = 40,000 (g/mol)  
SP-A is a high negatively charged polymer with a non-ionic backbone consisting of long thin side chains, which results in a strong affinity towards the surface of the cement particles through electrostatic adhesion, ensuring high mechanical resistance for shorter periods. SP-B is a lower negatively charged polymer with a non-ionic backbone consisting of shorter and thicker side chains, resulting in a slower adhesion to cement particles providing moderate mechanical resistance for longer periods. The peaks of the graph in Figure 1 were considered for the calculation used by [PERSON] (2013) [16] to define the hydrophilicity of the side chains using FTIR results of the two admixtures. The ratio between the hydrophilic Ester groups and the hydrophobic Ether groups of the PCE structure is used to determine the hydrophilicity of the side chains. The first method used the absorbance from the peaks (Ether absorbance/Ester absorbance) to calculate the hydrophilicity and the second method used the area of the peaks (Ether area/Ester area). Equation (1) was then used to calculate the absorbance from the transmittances. It was determined that both methods used confirm the assumption made about the polymers and established that SP-A has a greater hydrophilic nature compared to SP-B, which translates to SP-A being, theoretically, more efficient in increasing fluidity because of its longer side chains.