## 3 Results and Discussion
### Creep  
The creep can be divided into three categories from a low to high stress-strength ratio. When the stress level is low, which some authors call service stress, the creep strain is linearly related to the stress. We call this case convergent linear creep, or simply linear creep. As the stress-strength ratio increases, the creep strain is nonlinearly related to the stress, whereas the rate of increase in the creep strain decreases. This case is called convergent nonlinear creep. In this case, although microcracks are generated from the stress, they are not further developed. When the stress-strength ratio increases to a certain extent, the microcracks become more numerous, wider, and joined together. These factors lead to uncontrolled creep growth and eventually to a break of the specimens. This case is called non-convergent creep. The dividing points of linear creep and convergent nonlinear creep of OPC concrete for the current creep models were approximately 0.4 (B3, CEB-FIP 2010, and GL2000) and 0.5 (ACI 209R-92). However, there is no consensus of the dividing point of the convergent nonlinear creep and non-convergent creep of OPC concrete. Some scholars have carried out relevant studies, suggesting a range of 0.7-0.9 [26; 27; 28; 29; 30]. The stress-dependent strain is the sum of the creep strain and elastic strain, the specific creep is the creep strain based on the unit of stress, and the creep coefficient is the ratio of creep strain to the  
Figure 4: Shrinkage strain of AAS concrete from day 3. (**a**) shrinkage strain; (**b**) shrinkage rate. \begin{table}
\begin{tabular}{c c c} \hline \hline
**Model** & **Compressive Strength (MPa)** & **Elastic Modulus (GPa)** \\ \hline AAS & 43.53 & 15.4 \\ ACI 209R-92 & 43.53 & 36.5 \\ B3 & 43.53 & 31.2 \\ CEB-FIP 2010 & 43.53 & 35.1 \\ GL2000 & 43.53 & 31.9 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Elastic modulus of model calculation. elastic strain at the start of the loading time. Samples with a stress-strength ratio of 0.75 broke during the loading time, as shown in Figure 5, and thus are not shown in the data in the following figures. Figure 6 shows the stress-dependent strain, specific creep, and creep coefficient of AAS concrete with different stress-strength ratios for 300 days (beginning at 28 days). Smooth growth curves benefit from good temperature and particularly humidity control. Figure 5: Broken specimens under stress–strength ratio of 0.75. Figure 6: _Cont._  
As Figure 6a shows, the stress-dependent strain of all stress-strength ratios increases as the age increases and the rate of growth tapers off. In addition, the stress-dependent strain increases significantly by the growth of the stress-strength ratio. The curves of 0.15-0.6 show convergence; however, one of the two samples with a stress-strength ratio of 0.75 was broken during the loading time and showed non-convergence. As described in the previous experiment steps, the load was slightly higher than the experimental value because plate B incurred some deformation after being fixed. Thus, the actual stress-strength ratio at the loading time was over 0.75. While the eccentricity is not the reason of the failure because we were very careful with the eccentricity. The most time-consuming step of loading time is the centering and we usually need more than five times loading process. The results of the stress-dependent strain indicate that the dividing points of convergent nonlinear creep and non-convergent creep of AAS concrete are above 0.6 and approximately 0.75. Compared with the stress-dependent strain, the specific creep allowed us to analyze the creep without the effect of stress. As shown in Figure 6b, there are significant distances between the curves. If a linear stage occurs, the specific creep curves of some stress-ratios will be combined. Thus, this result indicates that AAS concrete does not have an obvious range of linear creep, even at a low stress-strength ratio.