The disclosure provides strengthened products, including strengthened fibrous composite products and methods for making and using same and strengthened particulates, such as particulate fertilizer products, and methods for making and using same. The fibrous composite product can include a plurality of fibers and an at least partially cured strengthening resin. The fertilizer composition can include a particulate core that can include a plant nutrient, at least one coating layer of the strengthening resin, and at least one coating layer of a water insoluble material. The strengthening resin can include one or more aldehyde-based resins and one or more crosslinked resins. The crosslinked resin can include one or more polyamines at least partially crosslinked by one or more symmetric crosslinks and can include one or more azetidinium functional groups.
