Design a paving with natural stone

It would like in this entrance remember the importance to design the pavings of stone having always special care in doing it in function of the type of traffic that go to bear. This arises me after reading does some days a news in this regard, in the Newspaper of Cádiz, in which they analysed the causes of the break of a paving of granite slabs, that can see in the following link:

http://www.diariodecadiz.es/article/provincia/1684374/una/media/vehiculos/circula/diario/por/cada/tramo/la/calle/real.html

Design a paving with natural stone requires of a careful calculation of each one of the elements that constitute it. For this, is necessary to know previously the characteristics of the loads of traffic so much in his quantity as in intensity during the useful life of paving.

From the experience can affirm that the breaks of the pavings with slabs owe , in the greater part of the cases, to errors in the design of the same, to the not quantifying properly the planned traffic, and hardly ever to the stone used.

If we speak of pavings with slabs, an important concept to know is the one of «equivalent axes». The load that transmits each vehicle that goes through a paving corresponds with the maximum load by axis, that comes defined in the index card of characteristics of the vehicle. This, it is necessary to transform it in what we designate equivalent axes, that will serve us for the calculation of the thickness and that they are the axes of 13 tonnes by day that transitan by the paving.

Regarding the number of vehicles that go through the paving, will take in consideration only the number of Heavy Vehicles by Day (VPD), that are the ones of more than 200 give of weight. A precise calculation of the VPD has to effect  from real capacity, especially when the traffic of heavy vehicles was intense, what does not result especially complicated when it treats  of the streets of a city, since they are easily countly.

The factor of conversion of an axis of P tonnes, in equivalent axes of 13 t, comes given by the expression situated further down.

When it does not have real capacity it is possible to do an estimate of the number of equivalent axes/year, for some usual spaces, by means of values tabulated.

For a more detailed information about how calculate thicknesses in function of the type of traffic, can consult  the web www.tecnicagranito.es or the "Guide for the design, construction and maintenance of external pavings of natural stone", that can find in www.fctgranito.es in the section of Publications.