# Abrasion-Resistant and Temperature Control of
## 2 Anti-Scouring and Abrasion-Resistant Performance Test on Concrete
### Test Results and Discussions
#### 2.3.2 Silica Fume Effect  
Table 5 provides the results of the test on high-strength concrete performance using silica fume. Figure 6 shows the change trends of the compressive strength, anti-scouring and abrasion-resistant strength and volumetric dry shrinkage rate of concrete with test age at different dosages of silica fume (5%, 7% and 9%). \begin{table}
\begin{tabular}{c c c c c c c c c c c c c} \hline \hline \multirow{2}{*}{**Mixture No.**} & \multirow{2}{*}{**Silica Fume**} & \multicolumn{3}{c}{**Compressive Strength**(\%/MPa)} & \multicolumn{3}{c}{**Abrasion**} & \multicolumn{3}{c}{**Volume Shrinkage**(\(\text{U.4}^{-}\)**)} \\ \cline{3-13}  & & & \multicolumn{3}{c}{**Resistant(\(\text{fb}\)/(\(\text{cm}^{2}\))\({}^{-1}\))} & & & & & & & & \\ \cline{3-13}  & & \multicolumn{3}{c}{**Total G**(\%)} & \multicolumn{3}{c}{**Total G**(\%)} & \multicolumn{3}{c}{**Total G**(\%)} & \multicolumn{3}{c}{**Total G**(\%)} & \multicolumn{3}{c}{**Total G**(\%)} & \multicolumn{3}{c}{**Total G**(\%)} & \multicolumn{3}{c}{**Total G**(\%)} & \multicolumn{3}{c}{**Total G**(\%)} \\ \hline F20857P0 & 5 & 29.4 & 46.2 & 53.8 & 11.18 & 12.12 & -22 & -75 & -178 & -240 & -283 & -309 \\ F20857P0 & 7 & 30.8 & 52.2 & 58.8 & 12.02 & 13.04 & \(-\)24 & -88 & -183 & -248 & -294 & -326 \\ F20859P0 & 9 & 32.1 & 55.3 & 61.9 & 13.74 & 14.46 & \(-\)28 & -90 & -187 & -259 & -302 & -338 \\ \hline \hline \end{tabular}
\end{table} 
Table 5: Test results of silica fume effect on concrete. Figure 6: _Cont_. As shown in Figure 6a, the compressive strength of concrete increased with increasing dosage of silica fume; at the same dosage of silica fume, the increase amplitude of the compressive strength of concrete in the late stage was higher than that of the compressive strength of concrete in the early stage. At the age of 7 day, when the dosages of silica fume were 5%, 7% and 9%, the compressive strengths of the concrete specimen were 29.4, 30.8 and 32.1 MPa, respectively. Compared to the dosage of 5%, the compressive strengths of the concrete specimen at the dosages of 7% and 9% increased by 4.55% and 9.18%, respectively. At the test age of 90 day, they increased by 8.50% and 15.06%, respectively. This was because the ordinary concrete was loose with significant volumes inside and the cement was irregular in shape with sharp edges and corners. Under the surface tension of pore water, there would be no complete contact among particles. After adding silica fume, because of their small size and spherical shape, silica fume particles would fill in those pores, react with Ca(OH)\({}_{2}\) and produce high-strength and high-stability C-S-H crystals. As a result, C-S-H crystals would block the pore canals, reduce large pores, change the internal pore structure of concrete and significantly improve its strength. In addition, the silica fume added into concrete improved both the anti-scouring and abrasion-resistant performance and hardness of paste. The bonding status of the interface between the cement paste and aggregate could largely enhance the anti-scouring and abrasion-resistant performance of coarse aggregate and strengthen the anti-scouring and abrasion-resistant strength of concrete. In Figure 6b, at the age of 28 day, when the dosages of silica fume were 5%, 7% and 9%, the anti-scouring and abrasion-resistant strengths of the concrete specimen were 11.18 h(g/cm\({}^{2}\))\({}^{-1}\), 12.02 h(g/cm\({}^{2}\))\({}^{-1}\) and 13.74 h(g/cm\({}^{2}\))\({}^{-1}\), respectively. Compared to the dosage of 5%, the anti-scouring and abrasion-resistant strengths of the concrete specimen at the dosages of 7% and 9% increased by 7.51% and 22.90%, respectively, and at the test age of 90 day, they increased by 7.59% and 19.30%, respectively. Doping silica fume could improve the strength performance index of concrete; however, silica fume concrete faced the problem of plastic dry shrinkage in the early stage and was extremely susceptible to shrinkage cracking.