# Experimental Study of the Thermal and Dynamic Behaviors of Polypropylene Fiber-Reinforced Concrete
## 2 Materials and Methods
### Test Equipment  
A camber-type electric resistance furnace, as illustrated in Figure 1a, was employed to heat the concrete samples to a specific temperature in order to test the dynamic and thermal behavior of the ordinary concrete and the HPC under various loading rates and after various high-temperature treatments. The temperatures used in this research for the concrete samples were set as indoor temperature (25 \({}^{\circ}\)C), 100 \({}^{\circ}\)C, 200 \({}^{\circ}\)C, 400 \({}^{\circ}\)C, 600 \({}^{\circ}\)C, and 800 \({}^{\circ}\)C. Figure 1b shows the equipment used for maintaining a constant temperature for the specimens. As illustrated in Figure 2a, the TAW-2000 computer-controlled automatic  
\begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline
**Grade** & **Water** & **Cement** & **Fly Ash** & **Silica** & **River** & **Stone** & **Polypropylene Fiber** & **Water** & **Water** & **Binder** & **Sand** \\  & & & **Fume** & **Sand** & **Fiber** & **Reducing Agent** & **Ratio** & **Ratio** \\ \hline H-C30 & 160 & 234 & 108 & 18 & 714 & 1166 & 1 & 7.2 & 0.44 & 38\% \\ \hline H-C40 & 160 & 292.5 & 135 & 22.5 & 680 & 1110 & 1 & 9 & 0.36 & 38\% \\ \hline H-C50 & 160 & 351 & 162 & 27 & 646 & 1054 & 1 & 10.8 & 0.30 & 38\% \\ \hline H-C30-B & 160 & 234 & 108 & 18 & 714 & 1166 & - & 7.2 & 0.44 & 38\% \\ \hline H-C40-B & 160 & 292.5 & 135 & 22.5 & 680 & 1110 & - & 9 & 0.36 & 38\% \\ \hline H-C50-B & 160 & 351 & 162 & 27 & 646 & 1054 & - & 10.8 & 0.30 & 38\% \\ \hline \hline \end{tabular}
\end{table}
Table 6: High-performance concrete mix ratio (kg/m\({}^{3}\)).  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Characteristics** & **Parameters** & **Characteristics** & **Parameters** \\ \hline Color & White or faint yellow & Shape & Monofilament bundle \\ \hline Density & 1.18 (g/cm\({}^{3}\)) & Equivalent diameter & 9–30 um \\ \hline Length & 3–9 (mm) & Melting point & 220 (\({}^{\circ}\)C) \\ \hline Acid resistance & Excellent & Alkali resistance & Excellent \\ \hline Tensile strength & \(\geq\)900 Mpa & Elongation at break & \(\geq\)15–25 (\%) \\ \hline Elastic modulus & \(\geq\)13,000 Mpa & Water absorption & Water resistance \\ \hline \hline \end{tabular}
\end{table}
Table 4: Main performance parameters of polypropylene fiber.  
\begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline
**Grade** & **Water** & **Cement** & **River Sand** & **Stone** & **Polypropylene Fiber** & **Water**–**Binder Ratio** & **Sand Ratio** \\ \hline N-C30 & 215 & 360 & 693 & 1132 & - & 0.60 & 38\% \\ \hline N-C40 & 215 & 450 & 659 & 1076 & - & 0.48 & 38\% \\ \hline N-C50 & 215 & 540 & 625 & 1020 & - & 0.40 & 38\% \\ \hline N-C30-B & 215 & 360 & 693 & 1132 & 1 & 0.60 & 38\% \\ \hline N-C40-B & 215 & 450 & 659 & 1076 & 1 pressure-testing machine was used to carry out the static test for the normal concrete and the HPC. Figure 2b,c shows the specimens placed in the machine during testing.  
As illustrated in Figure 3, the split Hopkinson pressure bar (SHPB) was adopted to carry out the dynamic test for the normal concrete and the HPC, and comprised a gas gun, a striker, an incident bar, a transmission bar, and a dynamic strain meter system. To illustrate how the SHPB works, a schematic of the SHPB is given in Figure 4. During the test, the gas gun was used to accelerate the striker bar to impact on one end of the incident bar. Then, the dynamic compressive strain wave produced propagates towards the other end of the incident bar. During the interaction of the incident bar and the sample, some part of the compressive wave is reflected, while the remaining part of the wave propagates towards the specimen. As the transmitted compressive strain wave reaches the interface of the specimen and the transmission bar, the disk is subjected to dynamic loading.  
Figure 1: Equipment used for heating concrete specimens (**a**) and keeping the temperature constant (**b**).  
Figure 2: TAW-200 computer-controlled automatic pressure-testing machine (**a**) and working conditions (**b,c**).