Recon blocks were intentionally designed to be able to form curves. It is accomplished by tapering the sides of the blocks and contouring the shear key. There is a minimum radius that the typical Recon block can turn. It is largely determined based on the width of the block. The typical Recon block is 48 inches (120cm) wide. A smaller minimum radius is achievable using Recon Half blocks, 24 inches (60cm) wide. A mixture of full width Recon blocks, half blocks and fitting blocks can be used to create a radius in between the minimum radius of the full width block and the half block.
Considering the 1 inch (2.5cm) setback per course, the minimum radius varies depending on the height of the wall. On an outside radius the blocks come together as the wall is built up. Conversely, on an inside radius the blocks move apart. The minimum radii for an 8 foot (2.4m) tall Recon wall is as follows:
- Convex (Min. Outside Radius) Typical Recon Blocks 16 ft (4.88m), at base Recon Half Blocks 10 ft (3.05m), at base
- Concave (Min. Inside Radius) 15 ft – 10 in (4.82m), at top
- 8 ft – 10 in (2.69m ), at top
On an outside radius, cutting Recon blocks and/or Recon Fitting blocks is generally required at the ends of the radius to get back on to running bond. Cuts are usually alternated on either side of the radius to hide the cuts. On an inside radius adding half blocks and fitting blocks may be required.
Walls constructed vertically, theoretically, should stay on running bond and have a single minimum radius independent of the height of the wall.