whichhas to be properly prepared, or a newone,whichhas to be properly
constructed and preparedbeforeapplyingthe flooringin orderto allowa good
adherenceof the latter. It must be dry (a concrete slab must be let to dry for a
minimumof 28 daysbut this timemaybe far greaterif climatic conditionsare
not optimal)and ableto preventhumidityreaching the imperviousflooring.It
mustbe capableof withstandingall structural, thermal and mechanical stresses
and loads that will occurduringserviceand it must be sloped sufficientlyin
orderfor liquidsto flow to the drains. Thisis recommended for resin-based
floorsas wellas for ceramictiles,eventhough, traditionally, ceramic tiles are
appliedon a flat substrate, the slope being givenby the screed. Particular
attention mustbe given to jointsthat are an integral part of the floorsystem.
Nevertheless,it is not the purpose hereto detail all the constructionrules
regarding the substrate.For furtherinformation see Timperley (2002).
9.2.2 Flooring
Twofamilies of flooringmaterials are recommended for foodprocessing areas:
ceramic tilesand resin-basedfloors. Polyvinyl chloride (PVC) sheets are
considered unsuitable because theyare too easilyworn. Theycan become
crackedafterthe fall of a knifeor othersharpobject.
Ceramic tiles
Ceramic tiles are made of clay that after shaping is subjected to high
temperature. Theyare manufactured productsof constant qualityand have
been producedfor centuries. Vitrified unglazed ceramic tilesare recom-
mendedfor food processingareas. They are highlyresistant to the main
constraintsthat can be encounteredin foodprocessingpremises,especially to
heatshocks.The vitrified tilescan eitherbe pressed(in whichcasetheyare
usually square or hexagonal) or extruded (they are always rectangular).
Dimensiontolerancesof the pressedtilesare betterthanthoseof extruded
ones,allowingthinner joints.
Resin-based flooringmaterials
The first resin-basedflooring,the acrylic cementitioussystems, appeared in food
industry premisesduringthe 1960s and around two decadeslatersyntheticresin
flooringwas also proposed,withthe prospect of achievinga highstandard of
hygienebecause those floorings are seamless.However, a high degreeof
technical skillis necessaryto obtainin situa goodfinalproduct (onlyto be
appliedby a trained operative).As this has not alwaysbeenrespected,there
havebeenmanyproblemswithsuchfloors.
Resin-based floorsare obtainedby application of a mortarmade of a mix of
one or moreorganicor inorganicbinders,aggregates,fillersand additives,and/
or admixture,and can be classified according to the nature of the binder(s) used.
Thereare two familiesof binders: syntheticresinsand the hydraulicbinders.
The first onesare organic polymerscomprising one or morecomponentsthat
Improving the design of floors 169