## 2 Material  
### Aggregate  
Crushed basalt aggregate (CBA) produced from Tumen mountain, Jilin province in China, was crushed into four grades: CBA I (20-30 mm), CBA II (10-20 mm), CBA III (5-10 mm), and CBA IV (0-5 mm). The four grades of CBA will be screened into a single particle size, and the cement stabilized macadam test gradation is formed by a mix proportion design. RBA is taken from the demolition of the shanty renovation building in China, Jilin Province. It is crushed into two grades: RBA I (0-20 mm) and RBA II (0-5 mm). All these grades were applied to the experiment after sieving and then dispensed experiment gradation. The sieving results are shown in Figures 1 and 2. The experimental gradation of cement stabilized macadam was designed [20], which satisfies the gradation range stipulated in the Technology Guidelines for the Construction of Highway Roadbases (JTG/T F20--2015) and is close to the lower bound. The experimental gradation curve is shown in Figure 3.  
Figure 1: Grades sieving proportion. Figure 2: Grades sieving proportion. Several basic performance tests of aggregates, such as the crushed stone value, percentage of flat-elongated particle, water absorption, and apparent specific gravity were carried out on the basis of the Test Methods of Aggregate for Highway Engineering (JTG E42--2005). The plastic index test was carried out according to the Test Methods of Soils for Highway Engineering (JTG E40--2007). The results of the tests and the corresponding reference values in specification (JTG/T F20--2015) are shown in Table 1, and the coarse and fine aggregate were divided by a particle size of 4.75 mm. The CBA and RBA mixtures of different proportions were tested, whose proportions will be used in the experiment. According to the data in Table 1, as the proportion of RBA increase in specimens, the indexes such as the plastic index, water absorption, and crushed stone value also increase; however, the apparent specific gravity decreases at the same time, while the flat-elongated particlesare maintained a steady level. When only comparing two kinds of proportion, 0% and 100%, the apparent specific gravity of RBA (100%) is generally smaller than that of CBA (100%), and contraposing RBA, the fine aggregate is much smaller than the coarse aggregate. In terms of water absorption, RBA is 10 to14 times as much \begin{table}
\begin{tabular}{c c c c c c c c} \hline  & \multicolumn{3}{c}{**Fine Aggregate**} & \multicolumn{3}{c}{**Coarse Aggregate**} \\ \cline{2-7}  & **Plastic** & **Water** & **Apparent** & **Crushed Stone** & **Flat-Hongated** & **Water** & **Apparent** \\  & **Index** & **Absorption** (\%) & **Specific Gravity** & **Value** (\%) & **Particle (\%)** & **Absorption (\%)** & **Specific Gravity** \\ \hline
0\% * & 4.34 & 1.73 & 2.68 & 21.63 & 9.57 & 1.24 & 2.73 \\ \hline
20\% * & 6.16 & 3.89 & 2.99 & 22.85 & 9.53 & 3.75 & 2.69 \\ \hline
40\% * & 9.84 & 8.21 & 2.50 & 25.74 & 9.72 & 7.42 & 2.58 \\ \hline
50\% * & 13.97 & 10.32 & 2.41 & 28.45 & 9.89 & 9.98 & 2.51 \\ \hline
60\% * & 24.53 & 13.02 & 2.33 & 31.22 & 9.59 & 11.86 & 2.45 \\ \hline
80\% * & 40.64 & 15.53 & 2.24 & 38.41 & 9.63 & 14.97 & 2.39 \\ \hline
100\% * & 60.50 & 17.60 & 2.11 & 41.53 & 9.97 & 17.36 & 2.33 \\ \hline Reference value & \(\leq\)12 & — & — & \(\leq\)30 & — & — & — \\ \hline \end{tabular}  
* Replace proportion of recycled construction waste clay brick aggregate (RBA) in crushed basalt aggregate (CBA) specimens.  
\end{table} 
Table 1: Aggregate basic performance. Figure 3: Gradation curve. as CBA, which means that RBA can absorb more water than CBA under the same conditions. The crushed stone value of RBA is about twice that of CBA. This property leads to the strength of RBA being much weaker than that of CBA. The plastic index of CBA is much smaller than the reference value and less than that of RBA, which proves that the water absorption and water requirement of RBA are much larger than those of CBA, so it is not suitable to be used as aggregates alone.