Form liners are used in the construction of patterned walls, for instance, sound barrier walls erected along a freeway. A form liner is a contoured surface that is vertically positioned in relation to another set of surfaces to form a mold. A hardenable material, such as concrete, is then poured into the mold and allowed to harden. As a result, the contoured surface on the form liner produces a corresponding contoured surface on the hardenable material.
The contoured surface is used to create an aesthetically pleasing wall. Stone patterns are commonly used for this purpose. An important aspect to an aesthetically pleasing wall is a randomly patterned contoured surface. In other words, it is important that the pattern established between form liners does not appear redundant. Another important aesthetic consideration is to avoid visually obtrusive seams between form liners.
U.S. Pat. No. 5,232,646 (the '646 patent) describes a method of forming walls wherein interlocking form liners are used. The '646 patent is expressly incorporated by reference herein. In the '646 patent, each form liner has at least two non-linear mating surfaces. The non-linear mating surfaces are used to create the appearance of a random pattern. The problem with the technology of the '646 patent is that the non-linear mating surfaces can be difficult to align. In addition, the non-linear mating surfaces repeatedly interconnect in the same manner. Thus, the resultant pattern can become redundant.
U.S. Pat. No. 5,225,134 (the '134 patent) discloses another method to form contoured walls. The '134 patent is expressly incorporated by reference herein. The '134 patent generates a wall with a random pattern by using aligned interlocking form liners that create a continuous stone pattern between form liners. In other words, a portion of a stone is formed at each form liner border so that when two form liners are placed next to one another, a single stone pattern is formed. The problem with the approach of the '134 patent is that extremely precise alignment is required between adjacent form liners. In addition, the resultant stone pattern has a seam in it where the form liners met.
In view of the foregoing, it would be highly desirable to develop a new methodology of forming patterned walls that does not have the problems associated with prior art techniques.