Hardware installation with cores needs special attention. Although it does not rot, it also does not hold fasteners like wood. Attention needs to be given to how hardware is attached. Steve D’Antonio is a master at cored composites and has some great insights into this matter.
Composite materials are broadly defined as those in which a binder is reinforced with a strengthening material. In modern terms, the binder is usually a resin, and the reinforcing material consists of glass strands (fiberglass), carbon fibers or aramid fibers. However, there are other composites too, such as ferrocement and wood resins, which are still used in boatbuilding.
Check out ThoughCo.’s marine industry composite information:
Chris Rogers has a wealth of composites information. Go check out his site to learn more about working with recycled materials.
Explore Composites is a big how-to “book” about building with composites: tooling, materials, laminating and equipment. EC! is organized into Articles, Resources, Example Projects and Library sections. There’s a YouTube channel, Instagram and Discord for forum-like discussion.