resistance. Small aggregates that may be calledfillers have many roles.
Amongthoseare reducingshrinkageand increasingthe mechanicalresistance.
Suchaggregatesare oftenmadeof sandwithhighsilica content(SiO 2 or
quartz,7 on the Mohsscale).Hardaggregatesare usedto increaseresistance
to abrasion. Thosemaybe aluminiumoxide(Al 2 O 3 or corundum,9 on the
Mohsscale),siliconcarbide(SiC,commercialnamecarborundum,9.5 on the
Mohsscale).It mayhappenthat hardaggregateslead to an acceleratedwearof
shoesand of brushesusedfor cleaning.Largeaggregatesare usedto increase
slip resistance.
Primer
A primer(oneor two coats)is most generallyusedto aid the adhesion of the
finalflooringand to seal and consolidatethe surfaceof a poroussubstrate. It
consists of a liquidproduct, whichis oftena solvent-basedepoxy,applied to a
substrate.
Coats
Anti-slip resin-based floorings can be obtained by one-coat or multicoat
systems. Multicoatsystemsthatare the more frequently proposed are thin
flooring(2±5mm) madeof a self-levellingmortar on whichlargeaggregates are
sprinkled. One or two coatsand thenone or two finishingcoatscan be applied.
Thesefinishingcoatsare verythin,whichis whytheyhavea poordurability(1
or 2 years).Suchfinishingcoatscan be interestingwhentheyfill the bubble gas
holesbut theirrole should not be to maintain largeaggregates necessary to slip
resistance.
One-coat systems,also calledmonolithicsystems,are madeof mortar in
whichall the aggregatesare mixedpriorto application.The maximumdiameter
of the aggregatesmustbe smallerthan the thirdof the flooringthickness(Pollet,
2000).Theyare thicker(4±12mm)and the largeaggregatesnecessary to obtain
slip resistanceare oftenbettermaintained.
Gas removal
Gas bubbleholes are highlyundesirablefor hygienicconsiderations(see below).
Surface-activeagentscan be addedto avoid or decreasetheirformation during
polymerisationof resin-basedfloors.Thereis also prickle roller, calledhe¬risson
in French (hedgehog),that is usedwhen the mortar is in the fresh stateto release
entrapped gas bubbles.In some flooring,suchas polyurethane±cement, it is very
difficult to removegas bubbles and to prevent theirformation.Oneimportant
measure is not to apply suchflooringwhenroomtemperatureis increasing.
9.2.3 Jointing
Ceramic tile jointing
A jointingmaterial should completelyfill the gap between to ceramictiles right
up to the top edgeof the tile as shown on Fig.9.1. Thisis oftennot done
Improving the design of floors 171