"Crack Bridging" resin flooring is designed to withstand MINOR cracks which may subsequently develop in the floor substrate due to structural movement, concrete shrinkage, themal movement, static or dynamic loading.  The resin flooring is supposed to stretch elastically across the cracked substrate without damage.   This is especially important for car deck flooring which also serves as waterproofing deck to prevent water seepage to the level below.

 

For car park decking, it is usually effective for cracks <<2mm.  In fact, a lot of crack bridging systems failed at cracks much smaller. The reason for failure can be attributed to both the materials and more importantly, the applicators.  

 

Specifier intuitively thinks if a material has higher elongation (stretches like a rubber band), it will perform better in bridging cracks. Studies have shown that it may not necessarily be true (see our leaflet on "Crack Bridging...).  For minor cracks, stiffer materials with higher tensile strength may perform better than flexible, high elongation materials.  This is especially true in car decking applications where a flexible, high elongation flooring inherently may not have adequate tensile and tear strength to withstand the twists & turns of the rubber tyres, causing premature failures in many cases in Hong Kong and overseas.  

 

The applicator is another factor.  For a car deck flooring to elongate to bridge cracks, it needs to be at least 4mm thick and applied in multiple layers.  Each layer must be installed to strict specifications.  Many applicators, for the sake of saving cost, will "alter" the procedures and cut back on materials usage.  This is often fatal for car deckings.  Once a flexible decking system fails, it will require extensive and costly remedial repair.  In many cases, a complete resurfacing may be required.

 

Therefore, the specifier must be well advised of all the pitfalls and work with a reputable materials supplier and applicator when specifying crack bridging car deck systems.

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