# Application of Foundry Wastes in Eco-Efficient Construction Materials: A Review
## 5 Valorization of Foundry Waste in Construction Materials
### Waste Foundry Sand (WFS)
The results showed that the ideal water/binder (W/B) ratio and the WFS content improved the mechanical performance of the beams. Compared to the reference concrete, the composition of concrete with 20% WFS and a W/C ratio of 0.18 showed improvements in tensile and compressive strength. On the other hand, it was also possible to observe that in the specimens used, a smaller width and average spacing of the cracks were noted, despite an increase in the number of cracks, demonstrating better crack resistance. To determine whether the addition of calcined WFS as an additional cementitious material in the production of mortars is viable and effective, [PERSON] et al. [77] studied self-compacting mortars developed with the fine fraction of WFS. The objective of the study was to evaluate the behavior in the fresh and hardened state of the mortars, as well as to assess their microstructure and cement hydration. The use of calcined WFS increased the workability and compressive strength of the mortars developed with 10% WFS substitution, in addition to improving the initial hydration of the cement. There were also no evident differences in the microstructure of the mortars with up to 20% replacement. The study demonstrated that the substitution of cement with calcined WFS is a viable solution to reduce the amount of cement used in construction. In an investigation by [PERSON] et al. [78], bricks with WFS were produced in a fully operational industrial facility with high production capacity. The process included the creation, drying, firing, and mixing of clays and sands. Various tests were conducted on the bricks to evaluate properties such as bulk density, specific gravity, apparent porosity, water absorption, and wet compressive strength, in addition to investigating the structure and composition of the materials and the resulting bricks. According to the study, the bricks manufactured can successfully use up to 50% WFS, producing good results. The bricks with WFS maintained porosity, water absorption, and specific gravity like commercial bricks, but exhibited lower bulk density and compressive strength. [PERSON] et al. [79] developed a study aiming to repurpose various types of solid waste, including plastics and WFS from the steel industry, to manufacture bricks that meet international and local construction standards. The study concluded that the most suitable composition for recycled bricks is a 50:50 ratio of recycled plastic and WFS, offering optimal mechanical characteristics for application in masonry structures. These bricks exhibited twice the flexural strength, 1.36 times more tensile strength, and 21.8% less density than traditional bricks, in addition to lower water absorption, absence of efflorescence, and better thermal and electrical insulation properties, which can reduce energy consumption and lead to savings. [PERSON] et al. [80] investigated the use of WFS in the production of polymeric composites for construction. The researchers used WFS with melamine-formaldehyde resin and functional additives to improve performance and durability. The improvedformulation, composed of 15% polymeric binder and 10% additives, proved effective in reducing environmental impact and increasing the product's durability. In another study, [PERSON] et al. [PERSON] et al. (2018) investigated the use of WFS in conjunction with an epoxy-phenalkamine resin system to produce an artificial stone with better thermal stability, mechanical strength, and weather resistance. The study aimed to offer a solution for solid waste management. Furthermore, it suggested the use of a biological-based hardener instead of synthetic alternatives, which facilitates the creation of sustainable and ecological materials. The artificial stone created has demonstrated excellent resistance to bending, fire, abrasion, and chemical attacks, making it suitable for applications in both outdoor and indoor environments, such as kitchen countertops, flooring, and coatings.