Cementitious products are used throughout the world in buildings, roads, and infrastructures in both structural and non-structural uses. Typical cementitious materials used in producing cementitious products include but are not limited to mixtures of cement, fly ash, water, sand, gravel, and/or rock. Of course, other components including plasticizers, water proofing agents, cross linking agents, dyes, colorants, pigments, etc. may also be added to the cementitious material depending upon the desired physical characteristics. Two basic categories of cementitious product production are used and are the “wet cast” and “dry cast” methods.
The wet cast method uses a fluid mixture of cementitious materials that is poured in place such as a road or driveway, poured into a form such as a bridge support or reinforced building support, or poured into a mold to produce artwork. Wet cast cementitious material is characterized by a medium to high slump; or water to cement ratios greater than approximately 0.35. Typically, a wet cast product is separated from its form or mold only after cementitious curing.
The dry cast method uses a viscous mixture of cementitious materials that is typically formed in molds or extruded under material densification techniques involving vibration, vacuum, and/or significant forming force. Most high volume cementitious building products such as brick, paver, block, retaining wall block, tile, etc. are manufactured using a dry cast method. Dry cast cementitious material is characterized by a negative slump, zero slump, or low slump; or water to cement ratios less than approximately 0.35. Typically, a dry cast product is separated from its form or mold after the forming process and cures in a separate location which in turn enables mass production of dry cast products without the material costs associated with having a mold that is used throughout the curing process.
Cementitious mixtures and resulting products may vary from lower cost—utilitarian products to higher cost—market preferred or aesthetic products. Typical cementitious products are the same material throughout, even though only a small portion of the products will be visible when they are finally installed. For example, facing bricks used in home construction may only have one or two sides visible after installation, but the entire brick is made of the relatively high cost material. There is a need, therefore to have a product wherein only the visible faces are made of the higher cost material, with lower cost material on the inside, or non-visible portions, of the product.
So called “composite” products are known in the art. Typical composite products either join a less expensive base material to a more expensive market preferred facing material by bonding cured base and cured facing components in a secondary operation or involve some composite products formed with base and/or facing materials using a high percentage of expensive resins, epoxies, or other non-cementitious binding materials. Thus, there is a need for an affordable—market preferred or aesthetic composite cementitious based product that does not use non-cementitious binders to hold the disparate materials together.