Technical Resource Guide_WEB_BEL25-D-516650 - Page 10 of 84

10 | belgard ® product installation guide | belgard.com | 877-235-4273 Understanding Interlocking Concrete Pavement Interlocking concrete pavements (ICP) are flexible pavements designed to spread loads imposed on a small area of the pavement surface through a base layer (or series of layers or sub-bases) to a large enough area of the soil subgrade that the soil subgrade can support the load without rutting. The unique aspect of interlocking concrete pavements is that the pavers interlock to help spread the imposed loads. There are three kinds of interlock: vertical, rotational and horizontal. Variables that impact pavement performance: JOINT WIDTHS - consistent joint widths of approximately 1/8-in JOINT SAND - properly selected joint sand PAVER THICKNESS - 60mm (23/8-in) for pedestrian and some residential driveways 80mm (31/8-in) for heavy and industrial vehicle applications EDGE RESTRAINT - non-moving fixed edge restraint LAYING PATTERN - minimize length of uninterrupted joint lines in all directions. The most commonly used pattern is Herringbone. PAVER SHAPE - the length and width of the paver is an important consideration, particularly for vehicular applications. The aspect ratio (length divided by thickness) can provide guidance on application and distinguish between installation methods for pavers and slabs. Slabs have aspect ratios greater than 4. VERTICAL INTERLOCK This is achieved by the shear transfer of loads to surrounding units through the sand in the joints. This shear transfer also prevents one paver from moving vertically in relationship to its neighbor(s). ROTATIONAL INTERLOCK This is achieved through use of the proper paver thickness in relationship to load and use and by a perimeter edge restraint. A slight crown constructed into the pavement will increase rotational interlock and the load bearing capacity of the pavement. HORIZONTAL INTERLOCK This is achieved through the use of laying patterns that minimize the length of uninterrupted joint lines and disperse forces from braking, turning and accelerating vehicles. Certain geometrically interlocking paver shapes enhance horizontal interlock. Herringbone laying patterns provide the most effective horizontal interlock and should always be used in vehicular applications. DISPLACED SAND NO VERTICAL INTERLOCK DISPLACED SAND HORIZONTAL DISPLACEMENT NO ROTATIONAL INTERLOCK HORIZONTAL DISPLACEMENT HORIZONTAL INTERLOCK