# Thermomechanical Behavior of Textile Reinforced Cementitious Composites Subjected to Fire
## 3 Results and Discussion
### Bending Tests Results
#### 3.4.2 Results from 30-Minute Fire Tests  
Regarding all specimens that were exposed to fire for 30 min, it can easily be derived from Table 3 that the temperature reached at the level of the effective depth (level of the most stressed fibers) was, in all cases, higher than 520 \({}^{\circ}\)C (since the temperature in the middle is around 520-530 \({}^{\circ}\)C and the effective depth was closer to the surface). During the subsequent bending tests, it was observed that the fibers started to pull-out at very low load levels, and that practically no residual strength was left (see Figure 10), even though no severe cracks or spalling of the cover was observed. It was obvious that the coating of the textiles, being a thermoplastic material, had been completely burnt-off, and thus, the bond between the textiles and the mortar had already failed before the test. As a matter of fact, the fibers could be pulled out of the specimens even bare-handedly (see Figure 11b). Coating burn-off tests showed that the SBR coating used was almost completely burnt-off after reaching 500 \({}^{\circ}\)C (see Figure 7).  
Figure 10 gives the comparison of the load-bearing capacity of the not subjected and the subjected to fire testing specimens in Series A. Similar results were observed for Series B, C, D and F; therefore, the graphs for those series are not presented. No conclusions can be drawn regarding the effect of the nature of the fibers or the moisture content of the specimens.  
Additionally, it is worth mentioning that specimens in Series C and F developed a residual curvature after the fire testing (Figure 11a). These two series were characterized by a high geometrical asymmetry, as can be seen from Figure 2.  
ue to this asymmetry, the top layer (concrete cover of 12 mm), which was exposed to the high temperature and had no reinforcement, su  
Figure 11: (**a**) Curvature of specimens from the one-sided fire loading and the asymmetrical placement of the reinforcement; (**b**) specimen in Series C that was subjected to fire testing. The fibers were easily pulled out by hand after the flexural test of the specimen.  
Figure 10: Force versus displacement curves for specimens in Series A.  
thermal expansion. On the other hand, the bottom layer was subjected to lower temperatures and the textile that was concentrated near the bottom offered an increased axial stiffness to the lower part of the specimens. As a result, the thermal expansion was much lower at the bottom with respect to the top, which led to the curving of the specimens due to the thermal loading. The curvature was so intense that the surface was severely damaged (visible cracks). Thus, the damage, and therefore, part of the deformation, were irreversible (the specimens remained curved even after cooling down). The residual strength of these specimens was so low that two of them broke while being transferred from the furnace to the bending test set-up; thus, they were not tested at all. In addition, since no numerical results were obtained from testing these series, the effect of the increased concrete cover could not be quantified.  
The conclusions that can be drawn from these results, are:  
* The temperature stability of the coating of the textiles seems to be the most decisive parameter regarding the residual strength of the TRC specimens, since it directly affects the bond between the matrix and the reinforcement. Thus, extra care must be given when thermoplastic coatings are used in applications with fire safety requirements.
* The increased concrete cover could potentially protect the reinforcement better than a thinner cover; however, it is suggested that the same cover be applied symmetrically, so that a high geometrical eccentricity is avoided.