Unbound construction: As a standard construction method for paved surfaces, the unbound construction method has been introduced in DIN 18318 VOB C. This is the laying of the paving stones in a bedding layer about 3 to 5 cm thick (crushed sand-chippings mixture), underneath which is a coarse-grained base course of a crushed sand-gravel mixture. If the risk of frost is high, an additional frost protection layerunderneath the base course is necessary.
The sequence of layers and layer thicknesses of the superstructure (pavement, bedding, base and frost protection layer) are always based on the expected stress.
If it is not sufficiently permeable, the underneath is provided with a gradient of at least 2.5% in order to safely drain water or direct it to a drainage system. All layers must be filter-stable in relation to each other in order to avoid material leaching.
In the case of unbound construction, an edge edging of the surfaces is mandatory.
Image: Construction of unbound construction - bauwion
Usually, the joint filling is also carried out without binders in unbound construction, but when paving private areas, which are often not exposed to high traffic loads, the unbound construction method is often combined with bonded joints. This has the advantage that the joints remain maintenance-free (no washout of the joint material, no joint growth). Since the paving surface has a certain elasticity due to its design, the joint filler must also meet this property. High-strength joint fillers are generally not suitable for unbound construction.
Source: bauwion
