# Application of Foundry Wastes in Eco-Efficient Construction Materials: A Review
## 5 Valorization of Foundry Waste in Construction Materials
### Ceramic Mold Shells (CMS) and Paraffin Waves Waste  
Recently, studies have emerged revealing reuse options for ceramic mold shell waste (CMS), but companies are still exploring practical applications tailored to the specific characteristics of their regions. The precision casting industry faces a challenge, as CMS waste is currently not recycled. Recycling this type of waste can offer an environmentally advantageous solution, promoting the reuse of materials and reducing dependence on non-renewable natural resources [101]. Next, studies will be presented that explore the vaporization of investment casting waste (CMS and paraffin waves waste) in construction materials. The possibility of using CMS waste as cement replacement in concrete production was investigated by [PERSON] and [PERSON] [102]. The study analyzed the impact of these wastes on the physical and mechanical properties of concrete. The main conclusions indicate that the addition of 15% CMS increased the compressive strength of the concrete, and that the filling effect of the CMS reduced water absorption by immersion. It has thus been possible to conclude that the use of CMS as a partial substitute for cement brought benefits to the physical and mechanical properties of concrete. CMS was also used as a substitute for natural aggregate in cementitious materials. [PERSON] and [PERSON] [103] investigated the feasibility of replacing coarse aggregates with CMS waste in high-strength concrete. The residue was tested and characterized to be incorporated into samples at different proportions of 25%, 50%, 75%, and 100% as a substitute for coarse aggregates. Tests such as compressive strength, consistency index, water absorption by capillarity, and immersion were conducted. Compared to the reference concrete without the addition of waste, the results indicated that the waste is suitable for replacing coarse aggregates, even with 100% replacement, in high-strength concrete. The use of CMS waste as a sustainable substitute in the production of lightweight concrete was investigated by [PERSON] et al. [104]. Different compositions of lightweight concrete were prepared, replacing expanded clay with various proportions of CMS. The physical and mechanical properties of lightweight concrete were evaluated, and the results showed that the incorporation of CMS improved these properties. Furthermore, the findings indicated that a lightweight concrete with 80% CMS has potential for use in structures. CMS and paraffin waves were utilized as a substitute of natural aggregate in mortars by [PERSON] et al. [105]. The results demonstrated that the addition of these residues modified the performance (physical and mechanical) of the mortars, resulting in a reduction in workability, water absorption, and flexural and compressive strengths, due to increased  
Figure 13: Content percentage of EAFD in SCM, concrete, and mortars. microcracking. However, the mortars demonstrated satisfactory mechanical behavior despite these changes, suggesting a possible practical application. Subsequently, and with the aim of addressing the previously detected issues, [PERSON] et al. [106] evaluated the effectiveness of CMS waste treatment techniques to improve the mechanical and physical characteristics of mortars. Two treatment methods for CMS were proposed: washing and polyamide fibers incorporation. Based on the leaching tests, the washing treatment method proved to be effective in removing sodium, potassium, magnesium, chlorides, and sulfates. As a result, this was the method that demonstrated the greatest efficiency in controlling the expansive reactions of the mortars. In another study, [PERSON] et al. [107] evaluated the application of CMS and paraffin waves as alternatives to natural aggregates in cement mortars. The results showed that, under normal operating conditions, the incorporation of these residues resulted in mortars with adequate porosity, flexural strength, and compressive strength.