# Material Characterization for Sustainable Concrete Paving Blocks
## 2 Experimental Program
### Specimens Preparation  
The specimens were designed as concrete paving blocks with typical dimensions. Figure 2 demonstrates the process of manufacturing the concrete paving blocks in this project. The whole procedures, including preparing the concrete mixture, casting concrete paving blocks and curing, were in accordance with the actual industrial production standards by using a small scale brick-making  
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**Properties** & **Unit** & **Results** &
\begin{tabular}{c} **National Code** \\ **GB/T-18046 [19]** \\ \end{tabular} \\ \hline Density & g/cm\({}^{3}\) & 2.940 & \(\geq\)2.80 \\ Specific surface area & m\({}^{2}\)/kg & 455.000 & 400.00–500.00 \\ Mass loss on ignition & \% & 0.600 & \(\leq\)3.00 \\ MgO percentage & \% & 9.910 & \(\leq\)14.00 \\ \(SO_{3}\) percentage & \% & 1.825 & \(\leq\)4.00 \\ \(Cl^{-1}\) percentage & \% & 0.012 & \(\leq\)0.06 \\ Water percentage & \% & 0.010 & \(\leq\)1.00 \\ Activity index (7 days) & \% & 90.000 & \(\geq\)75.00 \\ Activity index (28 days) & \% & 98.000 & \(\geq\)95.00 \\ \hline \hline \end{tabular}
\end{table}
Table 3: Properties of ground granulated blast furnace slag (GGBS).  
machine as shown in Figure 3 with maximum pressing force of 80 kN. Before the casting phase, all the materials used in the experiments were completely dried in the oven for 24 h. At the concrete mixture preparation phase, water was added after the coarse aggregates, cement, and sand mixing in the mixer for two minutes, and then the whole materials were mixed for another three minutes. For one batch of the concrete mixture, the total mass was 60 kg for casting 20 concrete paving blocks. For one batch of blocks (20 blocks), five specimens were used to test the compressive strength, five specimens for tensile splitting strength, and the other three for water absorption, slip resistance tests, and abrasion resistance [15]. After casting, all the specimens were cured in a thermostatic chamber for 28 days until testing. The temperature in the chamber remained at 20 \(\pm\) 2 \({}^{\circ}\)C, and the humidity was controlled at 50% by the temperature and humidity controller.  
\begin{table}
\begin{tabular}{c c c c c c c c c c} \hline \hline
**Mix** & **RL** & **Water** & **Cement** & **NCA** & **NFA** & **RCCA** & **RCPA** & **Rubber** & **Glass** & **GGBS** \\ \hline  
\hline \hline \end{tabular} \begin{tabular}{|c|c|c|} \hline Coarse aggregate & Fine aggregate & \\ (including NFA, RCFA, \\ CG) & & (including NFA, RCFA, \\ \hline Dry in the oven for (24\(\pm\)0.5) \\ hours, temperature maintain & 100 \({}^{\circ}\)C. & Cooling to room temperature \\ \hline \hline \end{tabular} \begin{tabular}{|c|c|} \hline Put all the materials in a mixer, mixing for 5 mins \\ \hline \hline \end{tabular} \
\begin{tabular}{|c|c|} \hline Compact concrete \\ mixture into blocks by \\ brick making machine \\ \hline \hline \end{tabular}
\begin{tabular}{|c|} \hline Curing blocks on one \\ shelf in a thermostatic \\ chamber for 28 days \\ \hline \end{tabular}
\end{table}
Table 4: Mix proportions (kg/m\({}^{3}\)) of concrete paving blocks.  
Figure 2: The process of manufacturing the concrete paving blocks.