## 3 Results
### Penetrometer Tests
#### 3.2.2 Fine-Grained Silica Sand  
Results of the penetrometer tests performed on fine-grained silica sand samples are shown in Figure 8 (exact values are appended in Table A3). Four days after treatment, the water-treated control group had a maximum penetration resistance of 1.7 N (SD = 0.2).  
PolssaccharidesAt biopolymer concentrations of 1 wt% (XG = 0.25 wt%), all tested polysaccharide types formed crusts with considerably enhanced penetration resistances compared to the control group treated with water. Increasing the concentration significantly enhanced the penetration resistance of all tested polysaccharides, except for WS and XG, whose penetration resistance decreased.  
ProteinsRelative to the control group treated with water, all protein admixtures applied at 1 wt% concentration formed crusts with significantly increased penetration resistances. Compared to treatments at 1 wt% concentration, applications at 2 wt% resulted in the penetration resistance of all tested proteins increasing significantly, with FBPC, TG, and WP experiencing the most significant increases.  
Comparison of polysaccharide and protein treatmentsFor amendments at 1 wt% concentration, polysaccharide-induced crusts, on average, endured slightly higher penetration resistances than protein-induced crusts. While doubling the concentration significantly increased the penetration resistance of almost all samples, the penetration resistance of protein-induced crusts displayed a disproportionate increase relative to polysaccharide crusts. At the higher biopolymer concentration, the protein-treated substrates, on average, showed higher penetration resistances than the polysaccharides.  
\begin{table}
\begin{tabular}{l l r r r r r} \hline
**Group** & **Factor** & **SS** & **df** & **MS** & **F** & \(p\) \\ \hline \multicolumn{6}{l}{Medium-grained sand} \\ \hline \multirow{3}{*}{Polysaccharides} & Type & 1277.93 & 6 & 212.99 & 17.57 & \(<.001\) \\  & Concentration & 908.30 & 1 & 908.30 & 74.93 & \(<.001\) \\  & Interaction & 250.04 & 6 & 41.67 & 3.44 &.011 \\  & Error & 339.46 & 28 & 12.12 & & \\ \hline \multirow{3}{*}{Proteins} & Type & 1386.02 & 6 & 231.00 & 24.74 & \(<.001\) \\  & Concentration & 952.47 & 1 & 952.47 & 101.99 & \(<.001\) \\  & Interaction & 623.11 & 6 & 103.85 & 11.12 & \(<.001\) \\  & Error & 261.49 & 28 & 9.34 & & \\ \hline \multicolumn{6}{l}{Fine-grained silica sand} \\ \hline \multirow{3}{*}{Polysaccharides} & Type & 582.82 & 6 & 97.14 & 4.91 & \(<.001\) \\  & Concentration & 108.78 & 1 & 108.78 & 5.50 &.026 \\  & Interaction & 227.89 & 6 & 37.98 & 1.92 &.113 \\  & Error & 554.29 & 28 & 19.80 & & \\ \hline \multirow{3}{*}{Proteins} & Type & 1753.52 & 6 & 292.25 & 21.93 & \(<.001\) \\  & Concentration & 798.95 & 1 & 798.95 & 59.95 & \(<.001\) \\ \cline{1-1}  & Interaction & 298.17 & 6 & 49.70 & 3.73 &.007 \\ \cline{1-1}  & Error & 373.13 & 28 & 13.33 & & \\ \hline \end{tabular} Note. SS = sum of squares, df = degrees of freedom, MS = mean square, F = F-value, \(p\) = \(p\)-value.  
\end{table}
Table 4: Results of two-way ANOVA (\(\alpha\) =.05) of maximum penetration resistance measured by penetrometer.  
_Statistical analysis._ Results of the two-way ANOVA (Table 4) show that the types of polysaccharide (\(p<.001\)) and protein (\(p<.001\)) have a significant effect on the penetration resistance, with some biopolymers forming significantly stronger crusts than others. The concentration also has a significant effect on the penetration resistance (polysacchardie: \(p=.026\), proteins: \(p<.001\)), whereby doubling the concentration significantly increased the penetration resistance of most tested amendments.  
_Conclusions._ On fine-grained silica sand, all biopolymers produced crusts with significantly increased penetration resistances relative to the control group, with the biopolymer type having a significant effect on the resulting penetration resistance. The effect of doubling the concentration strongly depends on the biopolymer type, whereby most biopolymer treatments exhibited significant increases.