Which interlock type has the load absorbed by bedding sand and surrounding pavers, and fails when wide/open joints allow pavers to twist?

Which interlock type has the load absorbed by bedding sand and surrounding pavers, and fails when wide/open joints allow pavers to twist?

• A. Geotextile
• B. Vertical
• C. Rotational
• D. Horizontal

Answer: (B)

Vertical interlock relies on the load being carried primarily by the bedding sand and the surrounding pavers themselves. When pavers sit tightly together, the sand and adjacent pavers form a stable block that resists vertical and some lateral movement. If joints widen or open, that restraint is lost and the pavers can twist or rotate under load, leading to failure. This is different from other interlock types that depend more on friction along edges (horizontal) or corner-to-corner engagement (rotational). The scenario described matches the vertical interlock mechanism.

Vertical interlock relies on the load being carried primarily by the bedding sand and the surrounding pavers themselves. When pavers sit tightly together, the sand and adjacent pavers form a stable block that resists vertical and some lateral movement. If joints widen or open, that restraint is lost and the pavers can twist or rotate under load, leading to failure. This is different from other interlock types that depend more on friction along edges (horizontal) or corner-to-corner engagement (rotational). The scenario described matches the vertical interlock mechanism.