The expensive alternative to concrete would be to switch to epoxide resin bonded concrete. Use natural plastics. The formulations exist already and are comparab

The expensive alternative to concrete would be to switch to epoxide resin bonded concrete. Use natural plastics. The formulations exist already and are comparable. The main downside in some cases is they're harder, so post machining is also harder and more expensive. It works with sea sand too. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6416622/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6416622/