## 4 Conclusions  
In this study, the feasibility study on textile sludge as a raw material for sintering lightweight aggregates was explored. According to the test results and analysis, the major findings are summarized as follows:  
1. The total content of SiO\({}_{2}\), Al\({}_{2}\)O\({}_{3}\), and Fe\({}_{2}\)O\({}_{3}\) in the water purification sludge was 84.77%, which could be used as a source for the sintering of lightweight aggregates. In the textile sludge from Sample A, Sample B, and Sample C, the total contents of SiO\({}_{2}\), Al\({}_{2}\)O\({}_{3}\), and Fe\({}_{2}\)O\({}_{3}\) were 59.77%, 25.79%, and 29.2%, respectively, which were far lower than the required 75% threshold. As such, the selected textile sludge could not produce a glassy melt and could not be sintered into lightweight aggregates. Therefore, textile sludge can only be used as an auxiliary component for sintering lightweight aggregates;
2. Regarding the chemical composition of the raw materials used for sintering lightweight aggregates, the ratio of mineral composition (SiO\({}_{2}+\) Al\({}_{2}\)O\({}_{3}\)) to flux oxide content being within the range of 3.5 to 10.0 means that the material is considered a better raw material source. Among the textile sludge samples, the ratios of the (SiO\({}_{2}+\) Al\({}_{2}\)O\({}_{3}\))/fluxing oxide content in Sample A, Sample B, and Sample C were 3.92, 10.34, and 12.90, respectively. Sample A showed a better range, while Sample B and Sample C were not within the preferred range;
3. According to the \"bloating area\" of [PERSON]'s three-phase diagram designed to assess the chemical composition of lightweight aggregate raw materials, it was feasible for the water purification sludge to be sintered into lightweight aggregates. In contrast, the SiO\({}_{2}\) content of the three textile sludge samples was too low to show up in the \"bloating area\";  
Figure 18: Unit weight and classification of lightweight concrete. After the water purification sludge was blended with 7.5% and 15% of textile sludge from Sample A, the compositions were within the \"bloating area\" and thus were considered suitable for producing lightweight aggregates. In addition, after the water purification sludge was blended with 7.5% of textile sludge from Sample B or Sample C, its composition did fall within the \"bloating area\". However, the composition of the water purification sludge blended with 22.5% of textile sludge was not within the \"bloating area\";
5. At the same sintering temperature, the more textile sludge that was added, the greater the loss on ignition of the aggregates that were sintered with water purification sludge blended with textile sludge (which was between 9.74% and 21.19%). Among them, the loss on ignition was the largest when adding 22.5% of textile sludge;
6. The textile-sludge-based LWAs had certain basic properties. At the sintering temperature of 1150-1200 \({}^{\circ}\)C and adding textile sludge from Sample A, Sample B, and Sample C, the particle density ranges of the sintered aggregates were 0.54-1.1, 0.6-1.23, and 0.69-1.19 g/cm\({}^{3}\), respectively;
7. The compressive strength of the lightweight aggregate concrete made from textile-sludge-based LWAs could meet the general strength requirements of lightweight concrete. This means that textile-sludge-based lightweight aggregate can be used in secondary structural concrete, such as steel bridge decks or lightweight partition wall panels for buildings. Its weight reduction effect is very good, which can greatly reduce the cost of construction. LWA is generally manufactured by high-temperature sintering, which is an energy-consuming industry. However, the sintered LWA has the properties of green building materials, such as being lightweight, heat insulating, and earthquake resistant. In particular, textile sludge has a certain thermal matrix (high loss on ignition), which can provide part of the heat energy when sintering LWA, so it has economic benefits.