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The hardscape industry continues to grow and so to does the technology of how the products are made. Today’s pavers are not made equal to yesterday’s. Though similar processes remain, new processes have been added to ensure the longevity of the product as well as the visual appeal of it. From dry cast to wet cast and through mix to face mix, these are some of the new technologies that are used to push the industry forward in providing clients with the best possible end product.
With paver installations dating back to the Romans, the embracing of interlocking pavement continues to be embraced in North America from vast adaptation in Europe and the benefits being evident. Today we see more and more interlock being sold and installed all across North America, though still lagging behind where Europe is. This shows that the industry is still so young here in North America and there is still a lot of potential for growth in the hardscape industry.
What Are Interlocking Pavers
Interlocking pavement is a flexible system that distributes the weight of a load from the surface of the pavement through to the base, protecting the subgrade from deforming by spreading that load over a wider area. Through the dynamic load placed on top of the surface, seasonal changes, added moisture content, and freeze-thaw cycles, interlocking pavement is still able to perform flexibly and return to form with minimal movement if installed correctly. This flexibility provides advantages over rigid systems such as concrete and asphalt as these crack with movement or expansion and contraction caused by temperature changes.
As stated by ICPI, interlocking concrete pavement help spread loads through three kinds of interlock:
Vertical interlock is provided by the sand in the joints of the pavers, transferring vertical loads to surrounding units with the shear force being withstood by the joint sands. Rotational interlock is provided by the pavers themselves being placed closely (1/16″ to 3/16″ joint widths with wider joints providing less interlock) and restrained properly at the edges to prevent horizontal displacement. Horizontal interlock is provided from the same, but with the additional support of laying patterns (herringbone being the strongest) that are able to withstand the forces that the pavement experiences from larger traffic loads.
How Are Pavers Made
Pavers are made simply by adding the necessary ingredients including aggregates, cement, pigment color, additives and mixing them; adding them to a mold; and then compressing and vibrating them to meet the standards set by the manufacturer. From there they are put into a kiln to cure, stacked on a pallet, and sent off to distributors to be sold. There are two types of pavers that are made and are highlighted below.
Dry Cast Pavers
This refers to pavers that are manufactured with very little water, just enough to hydrate the cement within the mixture. The aggregates, cement, pigment color, and additives are mixed together and poured into a mold where it is compressed and vibrated to meet the manufacturer’s strength specifications. It is then moved to a kiln to cure before being palletized and sent off. Because of their water to cement ratio, they are an optimal choice for commercial projects and heavier load projects in addition to any residential projects. They are also more consistent in variances when it comes to their dimensions and are less expensive than the wet cast alternative.
Through technological advancements, there are two types of dry cast paver options:
Through Mix Pavers
Face Mix Pavers
These pavers follow the manufacturing process above, mixing all of the ingredients together including the color and manufacturing the paver as a whole. In this case, the paver has color all of the way through the paver. If you break the paver in half, you will see the color blend appears all the way through. These pavers have a less consistent surface as the larger aggregates can provide some small air pockets to show. Additionally, over time the wearing of these pavers can cause larger aggregates in the mixture to show through on the surface. However, technology has added to the longevity of these pavers before this occurs.
These pavers have the strength of the larger, coarse aggregates from the bottom of the paver to the top with an added fine wear-resistant aggregate with concentrated color pigment added to the surface of the paver. This ensures that the paver remains structurally strong with the surface resisting fading or having the larger aggregates of the pavers showing through. These pavers can lend themselves to more unique surface textures and are more costly than through mix pavers.
Wet Cast Pavers
These pavers are mixed together with a higher moisture content or a high slump which allows it to be poured into a mold and vibrated to allow the material to settle and release any air bubbles from the mix. Once the concrete cures, the mold can be removed and the product can be palletized and shipped. Typically wet cast pavers are smooth in appearance and to the touch. They are typically more expensive than dry cast pavers and increasingly these products are being manufactured factory sealed adding to their cost. They also typically have a higher variance between units that are produced.