High sulfate content in the waste can be tolerated by using Type II or Type V portland cements rather than the typically used Type I cement. Additives have been developed to overcome the effects of several of these interfering agents. Some of these additives are clay, vermiculite, soluble silicates, and some proprietary products. The advantages of cement-based techniques are the use of low-cost materials and common commercial concrete processing equipment that have no need for specially skilled operators. The main disadvantage is that most of the wasters are not chemically bonded. Hence, once subjected to acidic leaching, resolubilization of the metal hydroxides and carbonates becomes a major concern.