Engineered stone is a composite material made of crushed stone bound together by an adhesive, (most commonly polymer resin, with some newer versions using cement mix). The two common stones used in producing these products are marbles and quartz, the application of this product depends on the original stone used, for engineered marbles the most common application is indoor flooring and walls, while the quartz based product is used primarily for kitchen countertops. Related materials include geopolymers and cast stone. Unlike terrazzo, the material is factory made in either blocks or slabs, cut and polished by fabricators, and assembled at the worksite.
Engineered stone is less porous, more flexible, and harder than many types of natural stone. Less porous varieties are more resistant to mould and mildew than most natural stone types. Since it has a uniform internal structure, it does not have hidden cracks or flaws that may exist in natural stone. Its polyester resin binding agents allow some flexibility, preventing cracking under flexural pressure. But, the binding agents often continue to harden, leading to a loss of flexural strength over time. The polyester resins are not completely UV stable and engineered stone should not be used in outdoor applications. Continuous exposure to UV can cause discoloration of the stone, and breakdown of the resin binder.
When used as floor tiles, care is required in ensuring compatibility with the adhesive used. Reaction resin adhesives and rapid drying cementitious adhesives are generally successful, but bond failure can occur with other cementitious adhesives.