# Reactive Powder Concrete: Durability and Applications
### Main Properties of Reactive Powder Concrete  
High strength concrete (HPC) provides a high compressive strength with its typical microstructure. Nevertheless, the weakest point in this kind of concrete is the coarse aggregate. Reactive powder concrete removes such coarse aggregates and optimizes the microstructure by packing with particle gradation of all the concrete constituents to reach the highest density [17]. The lack of coarse aggregate minimizes the concrete's internal defects, i.e., microcracks and pore spaces. The resulting main mechanical property is the achievement of higher compressive strengths than the high strength concrete (HPC) [1, 2]. This compact microstructure is also the responsible of the low permeability and, thereafter, high durability [4, 5, 6, 7, 8, 9]. A weak point of the first generation of the reactive powder concrete is the relatively low tensile strength of about 8 MPa in some cases. Thus, it can only be used in reinforced or prestressed concrete structural elements, substituting partially transverse reinforcement. New RPC derivatives achieve tensile strength of 25-150 MPa and their fracture energy ranges over 1200-40,000 J/m\({}^{2}\). Currently, ultra-high-performance concretes (UHPC) have a high bond strength in addition to an ultra-high compressive strength. When UHPC is reinforced with discontinuous, short fibers, it exhibits a tensile strain-hardening performance of short distance cracks [18]. Non-linear models are used to predict the response and highlight the beneficial \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Material** & **Characteristics** & **RPC200** & **RPC800** \\ \hline \multirow{3}{*}{Cement} & Portland cement—type V & \multirow{3}{*}{955} & \multirow{3}{*}{1000} \\  & (ASTM C150) & & \\ Sand & Fine sand (150–400 \(\upmu\)m) & & 5000 \\ Silica fume & Silica fume (18 m\({}^{2}\)/g) & & 229 \\ Precipitated silica & Precipitated silica (35 m\({}^{2}\)/g) & & 230 \\ Super plasticizer & Super plasticizer & & 18 \\  & (polyacrylamide) & & \\ Steel fibers & Steel fibers (length 3 mm and & & \\  & diameter 180 \(\upmu\)m) & & 630 \\ water & Total water & 153 & 180 \\ \hline \hline \multicolumn{4}{c}{**Typical Mechanical Properties of Reactive Powder Concrete (MPa)**} \\ \hline \multirow{3}{*}{Compressive strength} & Compressive strength & \multirow{3}{*}{170–230} & \multirow{3}{*}{490–680} \\  & (cylinder) & & \\ Flexural strength & Flexural strength & & 25–30 \\ Young’s modulus & & & 54–60 \\ \hline \hline \multicolumn{4}{c}{1 A cement type V according to the ASTM C150 is a sulfate resistant cement. In Europe, this cement is designated as CEM 152.5 R-SR 5} \\ \multicolumn{4}{c}{according to the EN 197-1.} \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Typical composition, kg/m\({}^{3}\), and main mechanical properties, MPa, of reactive powder concretes RPC200 and RPC 800. \begin{table}
\begin{tabular}{c c c c} \hline \hline
**RPC Property** & **Description** & **Recommended Values** & **Types of Failure Improved** \\ \hline \multirow{6}{*}{Reduction in aggregate size} & Coarse aggregates are & \multirow{3}{*}{Maximum size of fine sand is} & Mechanical, \\  & replaced by fine sand, with a & & \\  & reduction in the size of the & & 600 \(\upmu\)m & Chemical and \\  & coarsest aggregate by a factor & & Thermo-mechanical \\  & of about 50 & & \\ Enhanced mechanical & Improved mechanical & Young’s modulus values in & \\ properties & properties of the paste by the & 50–75 GPa range & & stress field \\  & addition of silica fume & & Volume of the paste is at least \\ Reduction in aggregate to & Limitation of sand content & 20\% greater than the voids & By any external source (e.g., \\ matrix ratio & & index of non-compacted sand & formwork) \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Main properties of reactive powder concrete and recommended values [1,2].