# A Study on the Applicability of Waste Glass Wool and Waste Mineral Wool as Fiber Reinforcement
## 5 Conclusions  
This research was conducted to evaluate the applicability of using concrete reinforcement of waste glass wool and waste mineral wool secured from waste insulation that has passed the use period. The strength properties of concrete mixed with waste wool fiber and durability related to freezing-thawing and chlorine ion penetration were evaluated, and the overall conclusions are as follows. 1. As a result of reviewing the characteristics of fresh concrete mixed with waste fiber wool, it was found that when the amount of waste fiber wool mixed is more than 2%, the slump decreases sharply compared to the reference concrete. It can be concluded that this is due to the high absorption characteristic of waste wool fiber. However, it has been confirmed that the addition of waste fiber wool has little effect on air content. In conclusion, if more than 2% of waste fiber is added, it is assumed that it is necessary to add a water or a water reducing agent to satisfy the design slump. 2. In the measurement of the compressive strength of the waste fiber wool-added concrete, the compressive strength tended to decrease slightly because an interface that could affect the compressive strength of concrete was formed, and it was confirmed that up to 5% was added to waste glass wool fiber and 12% was added to waste mineral wool fiber. 3. As a result of the tensile strength measurement, the tensile strength increased for both types of waste fiber wool, and it was confirmed that the tensile strength increased as the addition rate of waste fiber wool increased. The maximum tensile strength increase rate at 28 days was found to be about 11% at 2.0% addition rate. As a result of measuring the tensile strength at 90 days by adding 2% waste fiber wool, the waste mineral wool maintained a strength increase rate of 11%, but in the case of the waste glass wool, the tensile strength further increased, resulting in an improvement effect in tensile strength of about 19%. 4. As a result of reviewing the freezing-thawing resistance of the waste fiber wool-added concrete, regardless of the type of waste fiber wool, it has been confirmed that the freezing-thawing resistance of concrete through the relative dynamic modulus of elasticity and weight retention rate improves when more than 2% is added. At a low addition rate of less than 2%, it was confirmed that there was no or insignificant improvement effect depending on the type and addition rate of waste wool fiber. Figure 28: Chloride penetration test results. This means that more than an appropriate amount must be added to form a network structure and support the expansion pressure generated during the freezing process. 5. As a result of the chloride ion penetration test, which is an element of durability, it was found that when waste glass wool was added, the total charge passed was similar to that of reference concrete regardless of the addition rate. But, in the case of waste mineral wool, the total charge passed increased as the addition rate increased, and in case of addition rate above 1%, the total level of charge passed was high. Therefore, it was confirmed that the addition of waste mineral wool had no effect on improving the permeability of concrete. The overall conclusions of this research are that, in the case of waste glass wool, the effect of reducing the compressive strength was insignificant even at high fraction, and the effect of improving the tensile strength was clear. Additionally, it was determined that waste glass wool can be used as a fiber-reinforcing material based on the results of the experiment assessing durability such as freezing-thawing resistance and chloride ion penetration. However, in the case of waste mineral wool, the improvement in tensile strength is clear, but the reduction in compressive strength is larger than that of waste glass wool, and the durability was disadvantageous. Therefore, it is believed that follow-up studies on other matters such as additional methods or application after reprocessing are needed. Methodology, D.-S.J.