# Durability of Textile Reinforced Concrete: Existing Knowledge and Current Gaps
## 2 Durability  
### Chemical Attack  
The existing literature mainly focuses on the influence of alkaline, saline, and acid solution attack on the mechanical properties of TRC composites [11; 12; 13; 14; 15; 16; 17; 18; 19; 20], as presented in Table 1. \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**Ref.** & **Fibre** & **Matrix** & **Standard** & **Methodology** & **Solution** & **Duration** & **Post-Exposed** \\ \hline \multirow{3}{*}{[13]} & carbon and & & & saline & & & \\  & PBO * & cement & AC434 & immersion & (ocean) & & \\  & & & & & & & \\  & & & & & & & \\  & & & & & & & \\ \hline \multirow{3}{*}{[11]} & \multirow{3}{*}{glass} & HPC & JSCE-E & \multirow{3}{*}{immersion} & alkaline & & & \\  & cement & & 549-2000 & & & & & \\  & & & & & & & \\  & & & & & & & \\  & & & & & & & \\  & & & & & & & \\ \hline \multirow{3}{*}{[14]} & E-glass, & & & & & & & \\  & AR-glass **,** & & ASTM E2098 & & & (16\% Ca(OH)\({}_{2}\), pH = 12.6) & 168, 720, 1440, & \\  & carbon, basalt, & & & ETAG 029 & & (16\% Ca(OH)\({}_{2}\) + 1\% NaOH + 1\% NaOH + 14\% KOH, pH = 13) & 4320 h at 20 & \\  & PBO, steel & & & & (0.2\% KOH, pH = 12.5) & & and 45 \({}^{\circ}\)C & \\ \hline \multirow{3}{*}{[12]} & hybrid fabric & & & & & & \\  & (carbon and & E-glass) & concrete & GB/T & \multirow{3}{*}{wet-dry} & saline & (each cycle & pull-out and \\  & & & 50082-2009 & & (5\% NaCl) & includes 12 h & flexural \\  & & & & & & wet and 12 h & \\  & & & & & & dry) & \\ \hline \multirow{3}{*}{[15]} & \multirow{3}{*}{AR-glass} & \multirow{3}{*}{lime} & & immersion & & & \\  & & & & & & 1000 h at 60 \({}^{\circ}\)C & \\ \cline{1-1} \cline{4-4}  & & & & & & 10 cycles (each & \\  & & & & & & cycle includes & \\  & & & & & & 2 days wet and & \\  & & & & & & & \\  & & & & & & 60 \({}^{\circ}\)C) & \\ \hline \multirow{3}{*}{[16]} & carbon & cement, & \multirow{3}{*}{RILEM MS A.1, 1998} & & & & & \\  & & & & & & (10\% Na\({}_{2}\)CO\({}_{4}\)) & \\ \hline \multirow{3}{*}{[17]} & \multirow{3}{*}{AR-glass} & hydrated & \multirow{3}{*}{-} & & & & \\  & and air lie & & & & & \\ \cline{1-1} \cline{4-4}  & & & & & & \\ \cline{1-1} \cline{4-4}  & & & & & & & \\ \cline{1-1} \cline{4-4}  & & & & & & \\ \cline{1-1} \cline{4-4}  & & & & & & & \\ \cline{1-1} \cline{4-4}  & & & & & & \\ \cline{1-1} \cline{4-4}  & & & & & & & \\ \cline{1-1} \cline{4-4}  & & & & & & & \\ \hline \end{tabular}
\end{table} 
Table 1: Summary of literature on chemical attack. Due to the lack of well-established standard procedures, various procedures have been followed, including immersing samples in a solution under different temperatures or concentration level or subjecting them to wet-dry cycles. Most studies have considered the role of alkaline environment, and only a few studies can be found on the effect of saline or acidic environments. In most studies, tensile tests are used to evaluate the changes in mechanical performance after exposure [11, 13, 17, 18, 20], and flexural tests [12] or the fibre-to-matrix bond tests [12] are the least popular. A few studies have also considered the changes of the bond strength between TRC as a repair material and a substrate (concrete or masonry) through pull-off [16] or single lap shear tests [19]. Carbon and glass are the most common studied fabrics, and less attention is given to steel, basalt, PBO or natural fibres, which are of most interest in strengthening applications. The type of fibre and coating used plays an essential role in the residual mechanical performance of TRC/TRMs, but the existing information in this field is still limited. Carbon fibres are generally considered the most resistant to chemical attack [8, 13, 14, 18, 21]. Steel fibres are durable under alkaline conditions [14] but can corrote under saline environments [19]. Glass and basalt fibres are the most susceptible to alkaline environments and for this reason have been the subject of most existing studies.