# Research on the Pavement Performance of Slag/Fly Ash-Based Geopolymer-Stabilized Macadam
## 3 Results and Discussion
### Dry Strinkage Test  
The effect of geopolymer dosage on dry-shrinkage properties of stabilized macadam is shown in Table 6.  
According to the data in Table 6, with increased dosage of geopolymer content, the maximum water loss, the maximum dry shrinkage strain, and the average dry shrinkage coefficient of the test pieces are all increased. When the mix proportion is same, the average dry shrinkage coefficient of slag/fly-ash-based geopolymer-stabilized macadam is slightly smaller than that of cement-fly-ash-stabilized macadam. The optimal water content of stabilized macadam is the highest with the largest dosage of geopolymer. Most water evaporation arises from the free water in test pieces at the early stage, which causes relatively greater water loss.  
\begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multirow{2}{*}{**Test Code**} & **Length of** & **Maximum** & **Maximum Dry** & **Average Dry** & **Initial** & **Constant Weight** \\  & **Test Piece** & **Water Loss** & **Shrinkage Strain** & **Shrinkage** & **Mass** & **after Drying** \\  & **(mm)** & **(\%)** & **(\(\mu\epsilon\))** & **Coefficient (\(\mu\epsilon\)/\%)** & **(g)** & **(g)** \\ \hline GFA-2 & 400 & 4.01\% & 187.1 & 46.7 & 9866.6 & 9486.1 \\ GFA-3 & 400 & 4.24\% & 231.2 & 54.5 & 9830.9 & 9431.0 \\ CFA-3 & 400 & 4.29\% & 261.3 & 60.9 & 9868.3 & 9462.4 \\ GFA-4 & 400 & 4.53\% & 321.4 & 70.9 & 9500.7 & 9089.3 \\ \hline \hline \end{tabular}
\end{table}
Table 6: Results of dry shrinkage.  
Figure 3: Strength loss of different binder stabilized macadam base materials after freeze-thaw cyclic tests.  
Figure 4a shows the relationship between the water loss rate and curing ages of the four groups of test pieces. The water loss rate increased with increasing of curing ages. It increases significantly within the first 15 d, and then becomes slight. The water loss rate of GFA-2 test piece reached 3.44% in the first 15 d; the water loss rate of the GFA-3 test piece reached 3.67% in the first 15 d; the water loss rate of the CFA-3 test piece reached 3.78% in the first 15 d; the water loss rate of the GFA-4 test piece reached 3.9% in the first 15 d. The water loss rates of the four groups of test pieces in the first 15 d accounted for about 85% of the total water loss rate, indicating that most water loss occurred at the early stage.  
Figure 4b shows the curve of the relationship between dry shrinkage strain and curing ages of the four groups of test pieces. The dry shrinkage strain of test pieces is also increasing as curing ages increase, which is almost consistent with the change in water loss rate. It increases rapidly in the first 15 d, which further proves that the evaporation of water in test pieces lead to drying shrinkage of the interior of test pieces.  
The change of cumulative dry shrinkage coefficient with curing ages in each group of test pieces is shown in Figure 4c. The accumulative dry shrinkage coefficient increases rapidly at the early stage due to the rapid water loss. Then, the increase rate slows down. The dry shrinkage coefficient first constantly increases but then decreases as the water loss of the test pieces constantly reduces.