# Composites Containing Felt Wastes from the Automotive Industry
## 2 Research Results and Analysis  
In terms of consistency testing, all samples during the test showed a semifluid consistency, which corresponded to a cone drop (S3) of between 100 and 150 mm and were, respectively, for CONTR--150 mm, F1.0--110 mm, F1.6--100 mm, F3.0--100 mm. It is worth noting here, however, that the mixture became less workable with an increasing felt content for two reasons. First, mechanical mixing was hampered by the waste fibres coming together. The second reason for less workability was water absorption by the absorbent recyclate. Relating the results of this study to those reported in the literature only confirms the regularity noted. The addition of nylon fibres [85] or carpet fibres [86], even amounts as low as 0.5% resulted in a marked decrease in workability. The differences between the workability of the control concrete and the addition remained insignificant at an addition of just 0.1%. Here, the difficulties described were overcome by using an experimental composite design system. This study has shown that using this type of recyclate will require similar operations each time concrete is designed using different quantities of fibres. Figure 3 shows the results of the specific density of the composites. As expected, the assessed specific density of the composite was the highest for the control composite (Figure 3). It amounted to 2.23 g/cm\({}^{3}\) and was 6.69% higher than that of the composite filled with 1% recyclate (2.09 g/cm\({}^{3}\)), 21.97% higher (2.09 g/cm\({}^{3}\)) than that of the F1.6 composite (1.74 g/cm\({}^{3}\)), and 23.31% higher (1.71 g/cm\({}^{3}\)) than that of the F3.0  
Figure 3: Results of specific density testing of composites. Figure 2: Temperature tests. (**a**) Test stand for the insulation test of the samples. (**b**) Test stand for the author’s fire resistance test. composite, respectively. The specific density value was recorded for the F3.0 composite (1.71 g/cm\({}^{3}\)). The value of 1.71 g/cm\({}^{3}\) qualified it as a lightweight concrete and made it possible to assume that it would be a composite with improved thermal insulating properties due to its lightweight filler content. Relating these results to those reported in similar works [76; 77; 78] only confirmed the apparent relationship. In the works cited, the values of the composites with the addition of felt ranged from 2.15 to 2.32 g/cm\({}^{3}\), which was only due to the lower recyclate content and the higher value recorded for the control composites. Figure 4 shows the results of the saturation test on the composites. The highest absorbency was recorded for the composite containing 3% recyclate and was as high as 21.58%. Subsequently, the absorbency tested for composites with decreasing recyclate content--decreased. It was 41.61% lower for the F1.6 composite (12.6%), 53.38% lower for the F0.1 composite (10.06%), and 71.03% lower for the CONTR composite at 6.25%. Similar results were observed in all cases initially reported in the literature [76; 77; 78; 79; 80; 81; 82; 83; 84; 85; 86]. The differences in the absorbability of the composites depended significantly on the type of fibre and its content as an additive. None of the studies reported such a high content of waste fibre (maximum of 2%). The value of 3% represented the maximum saturation of the composite with waste, which was dictated by the desire to produce an insulating composite. This translated into a high increase in saturation. In the literature, the values were closer to those reported for composites with a fibre content of 1%, with a maximum value of 15%. Figure 5 presents the results of compression strength tests on the composites. The composite without the addition of the CONTR recyclate had the highest recorded value in terms of compressive strength, 68.43 MPa. The other composites had a lower  
Figure 4: Results of the saturation test of the composites. Figure 5: Compressive strength results of the composites. strength the higher the recyclate addition.