The current invention provides methods for stabilizing wastes, preparing construction materials and stabilizing soils using compositions including hexametaphosphate, with or without other additives. More particularly, one method of the invention discloses a process for treating a variety of materials including solid and liquid-containing wastes, including for example, common debris or hazardous, radioactive or toxic waste. This method involves combining a waste material with hexametaphosphate, and in some cases other additives. The resulting amended waste may also be compacted. Another method involves use of hexametaphosphate compositions to prepare construction materials. This method involves combining hexametaphosphate with a starting material such as soil, soil-containing compositions, mine tailings, mill tailings and combinations thereof. The resulting mixture is then compacted. The method yields a solid material in which the hexametaphosphate chemically and physically binds to soil constituents, thus yielding a hard product which exhibits high compressive strength and excellent durability. An additional method provides compositions including hexametaphosphate which can be applied to stabilize soil surfaces, thereby providing a method for protecting soil surfaces against erosion and other forces. The present invention also provides construction materials and soil stabilized compositions containing hexametaphosphate.