The reinforced concrete slot units are bedded in different ways depending on the property of the substrate and the traffic area loading. Class D 400 channels correspond to Type I to DIN EN 1433; i.e. they do not require a foundation to absorb loads in the installed condition to dissipate the loads that occur during use. They are to be laid on a carefully compacted bed of gravel & sand or crushed rock (frostproof layer) and a concrete blinding layer. Class F 900 channel corresponding to Type M of DIN EN 1433. They are to be laid on a structurally calculated reinforced concrete foundation. If an exposure to moisture and de-icing salt can’t be excluded, the concrete qualities C 25/30 LP XC 2, XF 2, XA 1 or C 30/37 XC 2, XF 2, XA 1 must be used. In cases where water, which does not contain de-icing salt, reaches the foundation a concrete quality of at least C 25/30 XC 2, XF 1, XA 1 has to be used. The characteristic values for the formation under the foundation or blinding layer on which the structural calculation is based and, if applicable, the minimum dimensions and minimum reinforcement of the foundation are shown in the typical drawings of the installation and support/bedding of the respective load class. These specifications must always be complied with.

For load class F 900, the connection between the channel and foundation must be made using suitable installation or grouting mortar which is stable in volume. The mortar joint must at least correspond to the strength property of C 25/30, maximum that of C 40/50. Attention is to be paid to the mortar's resistance to frost and de-icing salt if subsequent moisture ingress to this joint cannot be prevented. 

If the base of Class F 900 manholes is made from concrete elements for road gullys according to DIN 4052, these elements are to be surrounded in in-situ concrete.

Reinforced concrete slot unit, Class D 400, Type I, installation and bedding

Reinforced concrete slot unit, Class F 900, Type M, installation and bedding