LCA End-of-Life Phase
The final phase of the LCA is the end-of-life. As highlighted before, both steel and zinc are 100% recyclable without the loss of any properties. Products/materials recycled at the end-of-life receive an energy credit in LCA, as recycling cuts down or eliminates waste, and conserves energy and natural resources (virgin material) by being reused. When a structure constructed with hot-dip galvanized steel is demolished, the galvanized material is captured and sent to a steel mill for recycling. While in the electric arc furnace (EAF), the zinc is captured as zinc-rich EAF dust and can be reused in the zinc production process. The molten scrap steel is then ready to be cast into new steel shapes (Figure 1).
The primary component of the hot-dip galvanized product, the steel, contributes the majority of the end-of-life credit (below). The same credit for the steel is provided whether it is painted or galvanized. However, the zinc of the HDG coating is also 100% recyclable, while the paint coating becomes a permanent part of the waste stream, or is burned off as emissions.
|End-of-Life||Primary Energy Demand (PED)|
|1 kg of HDG Steel||-8.61 MJ|