## 3 Results
### The Parameter Analysis for Each Cementitious Material in CCSDOT Model  
#### 3.2.1 Fly Ash  
ss\({}_{FA}\), \(\lambda_{FA}\) and \(i_{FA}\) are present in Figures 5-7, respectively. Most of ss\({}_{FA}\) are between \(-0.568\) and \(-0.327\) while the median of ss\({}_{FA}\) is \(-0.415\). ss\({}_{FA}\) are almost smaller than 0 graphically, except four outliers. Those outliers are supposed to have a great relationship with the categories of fly ash. There are two general classes of fly ash, including low-calcium fly ash (ASTM Class F) produced by burning anthracite or bituminous coal and high-calcium fly ash (ASTM Class C) produced by burning lignite or sub-bituminous coal [44]. In the four outliers where the value of ss\({}_{FA}\) is greater than 0 in Figure 5, the engineering or experiment adopts class C fly ash instead of class F fly ash. Since the reactivity of high calcium fly ash (class C) is much higher than class F fly ash [6] and class C fly ash exhibits similar properties to slag, therefor, the value of ss\({}_{FA}\) is greater than 0. The detailed interpretation will be provided later in discussion. Most of \(\lambda_{FA}\) are between 0.376 and 0.638 while the median of \(\lambda_{FA}\) is 0.504. Graphically, most of \(i_{FA}\) are between 1.310 and 1.635 while the median of \(i_{FA}\) is 1.502 in Figure  
In addition, Figure 8a shows the relationship between the \(ss_{FA}\) and different kinds of concrete mixed with fly ash, including concrete incorporated with fly ash and slag, concrete incorporated with fly ash only, and concrete mixed with fly ash and limestone flour. In general, the \(ss_{FA}(FA+SL)\) are smaller than the \(ss_{FA}(FA)\), while the \(ss_{FA}(FA)\) are smaller than the \(ss_{FA}(FA+LF)\) on the whole. In order to further reflect the distribution of \(ss_{FA}\), the 25 th percentile, median, and 75 th percentile of the \(ss_{FA}\) in different kinds of concrete are enumerated in Table 9. It's easy to conclude that the 25 th percentile, median, and 75 th percentile of \(ss_{FA}(FA+SL)\) are smaller than those of \(ss_{FA}(FA)\), while those of \(ss_{FA}(FA)\) are smaller than those of \(ss_{FA}(FA+LF)\) respectively.  
\begin{table}
\begin{tabular}{c c c c} \hline \hline  & _FA + SL_ & _FA_ & _FA + LF_ \\ \hline
25 th percentile & \(-0.758\) & \(-0.507\) & \(-0.296\) \\ median & \(-0.529\) & \(-0.413\) & \(-0.184\) \\
75 th percentile & \(-0.339\) & \(-0.336\) & \(-0.142\) \\ \hline \hline \end{tabular}
\end{table}
Table 9: The 25 th percentile, median, and 75 th percentile of 28-day compressive strength contribution coefficient of fly ash in different kinds of concrete.  
Figure 8: The 28-day compressive strength contribution coefficient of fly ash (**a**) and the factor of the compressive strength in later period of fly ash (**b**).  
Figure 7: The impact index of four kinds of each cementitious material.  
Figure 8b reveals the \(\lambda_{FA}\) in different kinds of concrete. Graphically, the \(\lambda_{FA}\)\((FA+SL)\) are greater than the \(\lambda_{FA}\)\((FA+LF)\) generally while the \(\lambda_{FA}\)\((FA+LF)\) are greater than the \(\lambda_{FA}\)\((FA)\) on the whole. The compressive strength in later periods of concrete can be improved by adding fly ash into the concrete mixture, due to the pozzolanic activity and filling effect of fly ash. Moreover, the 25 th percentile, median, and 75 th percentile of \(\lambda_{FA}\) in different kinds of concrete are enumerated in Table 10.