althoughit is technically possible.The gap mustbe as smallas possible and
applicatorsmust wait(for instance around1 to 2 hoursat 18±20ÎC for an epoxy
grouting),so that the grouthas begunto cure, beforethe first cleaningof the
floor. The jointing material has to absorb dimensionalvariations of tiles.Thatis
whythe bettertolerancedimensionsof pressed tiles,allowa jointaround 5±
7 mm wideinsteadof 6±10mm for extrudedtiles. The smallestjointsmaybe
obtainedwhenceramictiles are laid in a syntheticresinbed and thensubjected
to vibration.However, it is not advisableto havejoints smallerthan5 mm
because it willbe impossible to fill themdownto the bottom, as tilesfor
industrial purposeare thick.
A highdiversityof grouting products is available(epoxy, vinylester,etc.)
and descriptionsof all of themare not possiblehere.The choiceof systemis
governed by the chemicalstressesexpectedon the floorsurface. Cement grouts
are not suitable for foodprocessingareasbecause theyare highlyporous, acid
sensitive and havea poordurability when subjected to mechanical stresses.In
addition,a simple epoxygrouting will not resistthe acidicconditions of some
foodfactories suchas dairyfactories and an anti-acid grouting must be chosen.
Otherjoints
Among all the jointsnecessary in the constructionof floorsare: constructionor
day joints,expansionjoints, movementjoints, and isolation joints.All the joints
in the subfloor or floorbaseshouldbe carried throughoverlaymaterial and
filled witha suitablesealant. Joint fillers haveto be flexibleand are therefore
not as capableof withstandingheavyloads or aggressivechemical as the
adjacentfloor finish. They mustbe changed when worn.
Fig. 9.1 Unhygienicand hygienicjointing.172 Handbookof hygiene controlin the foodindustry