Requirements for clay pavers
Customers can choose between 2 products which differ in quality: the European clay paver DIN EN 1344 and the more traditional German Clay paver which also fulfills the DIN 18503 requirements. Both products carry the CE sign. Clay pavers also fulfill particular requirements for the limitation of water absorption and minimum body density.
DIN EN 1344:2013-12 Paving bricks and clay pavers which have been fired to sintering are now assessed and marked according to the same test procedures throughout the EU. In order to take into consideration all the varied conditions of use of clay pavers in the EU the harmonized European norm defines different quality classes: e.g. 3 classes for abrasion resistance (A1-A3,), 4 classes for slip and skid resistance (U0-U3) and 5 classes for stability (T0-T4) . The highest class in each group approximately meets the requirements of the old DIN 18503.
When paving work is carried out on the basis of ATV DIN 18318 – road construction, slab pavements and coverings- then the classes of the TL Pflaster-StB have to be taken into account. These classes are automatically valid and binding for standard assembly in construction contracts according to DIN 18318 unless other decisions have been laid down in the performance specifications. For use within Germany the highest class according to DIN EN 1344 is to be complied with. In detail this is:
– measuring span –class R1
– flexural strength-class T4
– abrasion resistance-class A3
– dew and frost resistance-class FP100
– slip and skid resistance-class U3.
Measuring span and dimensional tolerance
When testing flexural strength 10 clay bricks /pavers are measured with caliper gauges for length, width and thickness according to DIN EN 1344. For every measurement taken the average value of both the largest and smallest values is registered. For every value measured the variation from the average may not be greater than 0.4 times the square root of the manufacturer’s dimension. A secondary requirement is that within one delivery for the same project the variation between the largest and smallest value in class K11 for each measurement may not be greater than 0.6 times the square root of the manufacturer’s dimension.
To test the freeze-thaw resistance according to DIN EN 1344 the clay bricks are placed in a water bath at 80°C for 24 hours. Subsequently the clay bricks are sorted into a testing frame and frozen so that only one side is exposed to the frost. The clay is frozen through until the total amount of absorbed water is frozen. The water near the surface of the clay brick is thawed and frozen repeatedly. The damage to the clay bricks/pavers after 100 repetitions is their resistance.
The F0 class is thus only suitable for indoor use in Germany. The freeze-thaw resistance test in class FP100 showed no notable damage. These properties are not affected by traditional de-icing salts .
The load-bearing behavior of a clay paver in the paved brickwork depends essentially on the carrying capacity of the base. If the base deposit is uneven severe bending stress can arise for surfaces driven over or with considerable static loads. For such stressed clay paver brickwork the stability class T4 should at least be used. The flexural stability is measured on 10 damp end clay bricks or pavers stacked on the ends and stressed to breaking point. There are 4 estimated flexural strengths . Alternatively the flexural strength can be estimated by using the following equation:
L= breaking load (N)
S= distance between the beams
w=measured width of the clay brick(mm)
t= measured thickness of the clay brick(mm)
Estimated flexural strength= 3/2xLS/wt2
The abrasion resistance is tested according to DIN EN 1344 using the Capon-Test on unpolished clay bricks/pavers. The abrasion resistance is established by the loss of volume on grinding marks which are created on the surface of the clay brick using a grinding disc under predetermined conditions and using grinding material. The resistance against deep abrasion is calculated from the chord length of the grinding marks and is stated as volume V in mm³ of the abraded material. 3 classes of abrasion resistance are differentiated.
Slip/skid resistance is measured according to DIN EN 1344 with a skid resistance tester on unpolished clay bricks/pavers . These are sorted into 4 classes using the results (Unpolished Skid Resistance Value) . The producer lists these values in the designated classes of U0 to U3 (USRV=55) of Table 5 of EN 1344. These values listed are only valid for the declared surface area e.g. for the layout of the storage area.
DIN 18503:-12 Clay pavers- Requirements and Testing
As well as the “European” clay brick according to DIN EN 1344 there is also the tried and tested German clay brick norm according to DIN 18503:-12. Clay pavers are clay bricks according to the DIN EN 1344 but have special requirements as regards water absorption and body density. Since the European norm cannot cover all the traditional national product characteristics the DIN 18503 has partially been retained. So in December 2003 an additional norm was issued: the DIN 18503:2003-12. The new DIN 18503 contains the total regulation content of DIN EN 1344 and adds on the decisive criteria of “ water absorption” and “ body density”.
Water absorption: max. 6 M-%
Body density: min. 2.0 kg/dm³ or at least 1.9 kg/dm³ (average value), min 1.9 kg/dm³ (single value)
The water absorption of the clay pavers may not exceed 6 M.-% . If the sample is taken according to DIN EN 1344:2002-07, attachment A and the measurement was done according to 1344:2002-07, attachment C.3.2, then the highest acceptable water absorption is 6% relative to the mass.
The body density of clay pavers must correspond to at least 2.0 kg/de³ or at least 1.9 kg/dm³ (single value). If the sample is taken according to DIN EN 1344:2002-07, attachment A and the measurement was done according to DIN EN 1344:2002-07 attachment C.3.2, there must at least be an average value of 2.0 kg/dm³ and a single value of at least 1.9 kg/dm³ established. The identification of the body density by the producer is the lowest value of the average