Exposed aggregate pavers, granite or concrete setts, cobbles, or cubes – which to choose?

1. Types of paving material

1.1. Shapes

Pavers can be square, rectangular, hexagonal, irregular shapes or a combination of these. However, they are always designed so that they are easy to produce in large numbers and to lay over large surface areas. The easiest and fastest to lay are simple shapes such as squares and rectangles. When choosing the shape, you should also decide whether you want bevelled or sharp edges. When the edges are sharp, the joins between the pavers are barely noticeable, while bevelled edges result in clearly visible joins.

1.2. Paver size

Paver dimensions vary considerably – they are usually 10-30 cm, but you can also find those that are over 60 cm. The advantage of larger pavers is they can be laid faster, but they are also heavier and more expensive. All pavers are more or less of standard thickness – about 5 cm.

1.3. Paving materials

Pavers are most often made of concrete, although they can also be made of stone and wood. Concrete pavers are the cheapest; however, it goes without saying that the price should not be the only consideration. Above all, the material should be in harmony with the building, its architecture, shape, and style, but also with the environment that surrounds it. For example, if you have a house with classical architecture, natural stone and marble are the perfect choice, while for a modern home in an urban environment, contemporary concrete flags or exposed aggregate pavers are the way to go.

2. Preparing the substrate for paving

No matter what material you choose to use for the paving, you will need to prepare the substrate before laying the pavers. It’s particularly important that the substrate is well prepared for surfaces that will be used for vehicular traffic, otherwise they will begin to deteriorate very quickly. First, soil needs excavating down to a depth of 40 cm; this is then filled with a 2 cm layer of fine grade gravel, and then a 25-45 cm thick subbase of coarser grade material. A drainage membrane and 4 cm drainage layer is then laid over this subbase. When installing flags or setts, gaps should be left between them for pointing and grouting. Once the pavers are laid, the joints are filled and then a plate compactor is used to compact the pavers and secure them in place.

2.1. Paved surfaces for vehicular traffic

Concrete castings are usually of sufficient thickness for their resistance to pressure not to be an issue. However, the preparation of the substrate is crucial for them, too. If we are talking about a surface for a residential building where low frequency of vehicular traffic is expected, the subbase layer of finer and coarser grade material can be 20 cm, while for surfaces exposed to freight traffic, a subbase of at least 30 cm must be laid.

2.2. Paving a concrete substrate

It is possible to lay new paving over old paving or over a concrete surface. Paving concrete is quite simple. The surface needs first to be cleaned. Then the flags or setts are placed and the joints are filled. The disadvantage of paving over a concrete surface is that any subsequent work that may need doing cannot be carried out without breaking the concrete.

3. Granite setts/cobbles/slabs

3.1. Laying granite slabs

Laying large format granite slabs is an extremely demanding job and therefore it’s best to leave it to the professionals. Granite slabs are not always flat and often have uneven edges, so they have to be laid very precisely. First, the entire area needs to be measured out and then a plan drawn up to show how the slabs will be positioned. This is followed by levelling out any unevenness in the substrate and then a coating is applied for better adhesion. Stone slabs are laid on a thick layer of glue. Continuous horizontal and vertical lines must be left at intervals throughout the paving. These expansion joints help accommodate independent movement between adjoining paving areas and allow for expansion due to heat.

3.2. Laying granite setts and cobbles

Granite setts and cobbles are so strong that they were used to pave road surfaces long before asphalt was around. They can only be laid on well-compacted, flat, sandy substrates. They are arranged in an octagonal, diagonal, or arched pattern. If different colours of granite are used, the stones can also be laid to form a mosaic. Today, setts, cubes and cobbles are mostly used for paving pedestrian zones, town squares, and public areas where traffic is prohibited, or around historical sites. Driving on them is very uncomfortable. However, if you use them to pave your yard, you will be able to park on them without any problems and the surface will remain the same for years without any upkeep.

4. Concrete cubes/flags/setts

Concrete castings are a good choice for paving the yard. They are resistant to moisture and pressure and can be laid quickly and easily. Before laying the pavers themselves, it’s important that a drainage layer is installed as well as a well-compacted layer of fill material, 20 cm thick. Then comes a layer of bedding sand and this is what the pavers are laid on. The advantage of installing flags is that they can be easily lifted and put back as needed. Concrete castings can be square, rectangular, hexagonal, or even triangular.

5. Exposed aggregate pavers - price and characteristics

5.1. Characteristics of exposed aggregate pavers

Exposed aggregate concrete pavers are made by a washing off the top layer of cement paste to reveal the constituent aggregate. In addition to their aesthetic appeal, exposed aggregate pavers have all the characteristics of concrete pavers, including a favourable price. Exposed aggregate pavers are laid in exactly the same way as concrete pavers. Their standard dimensions are 40x40 cm.

6. Exposed aggregate or concrete pavers and granite cubes