# Abrasion-Resistant and Temperature Control of
## 2 Anti-Scouring and Abrasion-Resistant Performance Test on Concrete
### Test Results and Discussions  
#### 2.3.1 Fly Ash Effect  
Figures 4 and 5 show the change trends of the compressive strength and anti-scouring and abrasion-resistant strength of concrete with the test age at different dosages of fly ash. In the process of the experiment, three groups of tests were carried out in parallel for the same measurement and the average value of the three measurements was taken in order to minimize experimental result errors.  
As shown in Figure 4, the compressive strength of concrete decreased with increasing dosage of fly ash but increased with increasing test age. In the early stage of the test, the compressive strength of concrete increased rapidly but decreased at a relatively high dosage of fly ash. This was mainly because the failure of a large amount of fly ash particles to participate in the hydration reaction weakened the bonding between the cement paste and aggregate, which significantly reduced the compressive  
Figure 4: Effect of fly ash dosage on compressive strength of concrete.  
Figure 5: Effect of fly ash dosage on abrasion resistance of concrete.  
strength of concrete in the early stage. For instance, at the age of 7 day, when the dosages of fly ash were 10%, 15% and 20%, the compressive strengths of the concrete specimen were 34.5, 32.0 and 29.4 MPa, respectively. Compared to the dosage of 10%, the compressive strengths of the concrete specimen at the dosages of 15% and 20% reduced by 7.25% and 14.78%, respectively. In the late stage of the test, because of the pozzolanic effect of fly ash, fly ash particles reacted with the Ca(OH)\({}_{2}\) in the cement and generated calcium silicate hydrate (C-S-H) gel and calcium sulphoaluminate hydrate (C-A-S-H), which, as a cementing substance, gradually increased with increasing test age. Thus, although the strength of the concrete specimen in the early stage significantly decreased with the growth of age, the compressive strength of concrete rapidly increased in the later stage. At the test age of 90 day, when the dosages of fly ash were 10%, 15% and 20%, the compressive strengths of the concrete specimen were 55.2, 54.5 and 53.8 MPa, respectively, suggesting that the compressive strengths of the concrete specimen at different dosages were approximately equal to each other.  
The anti-scouring and abrasion-resistant strength of the concrete specimen also decreased with increasing dosage of fly ash. As shown in Figure 5, at the test age of 28 day, when the dosages of fly ash were 10%, 15% and 20%, the anti-scouring and abrasion-resistant strengths of the concrete specimen were 12.48 h (g/cm\({}^{2}\))\({}^{-1}\), 12.0 h(g/cm\({}^{2}\))\({}^{-1}\) and 11.18 h (g/cm\({}^{2}\))\({}^{-1}\), respectively. At the test age of 90 day, when the dosages of fly ash were 10%, 15% and 20%, the anti-scouring and abrasion-resistant strengths of the concrete specimen were 13.32 h (g/cm\({}^{2}\))\({}^{-1}\), 12.88 h (g/cm\({}^{2}\))\({}^{-1}\) and 12.12 h (g/cm\({}^{2}\))\({}^{-1}\), respectively. Compared to the dosage of 10%, the anti-scouring and abrasion-resistant strengths of the concrete specimen at the dosages of 15% and 20% were reduced by 3.85% and 10.42% and 3.30% and 9.15%, respectively.