recognised that to prevent slipping accidents it is necessary to use two
complementarymethodsfor assessmentof the slip-resistanceof floors in the
laboratory and in the field(Leclercqet al., 1994).
Amongthe numerouslaboratorymethodsto comparenewsurfacesare the
ramptest and testsbasedon the evaluation of a coefficientof dynamic friction
between an oiled surfaceand an elastomer (as the one chosen by the French
NationalInstituteof Researchand Safety). The ramptest (Germanstandards) is
conducted by two people.Theyeachin turnfacedownhillwithan upright
posture,and walkforwardsand backwards on the floor surface.Duringthe test,
the test person graduallyincreasesthe gradientof the floor surfaceuntil an
(acceptance)angle is reachedwherethe test personeitherslipsor becomesso
insecure as to refuseto continuethe test. To assess slip resistancein the field
wheresurfaces are oftenworn and soiled, the French NationalInstitute of
Researchand Safety usesa portable device developedin Sweden by Ohlsson,
called the portable friction tester(PFT). It is basedon the continuous evaluation
of a coefficient of dynamicfrictionovera variable distance betweenthe surface
to be testedand an elastomer.
9.4.2 Hygiene
The European HygieneEngineeringand Design Group(EHEDG)TestsMethod
Subgroup is aboutto produce a guideline document on the testingof the
hygienic qualities of flooring materials. Twotest methodsare proposed:a
surfacewaterabsorptiontest and a cleanability test.
The surfacewaterabsorptiontest is basedon a test derivedfromthe National
Swedish Institute for Materials Testing, Test Regulation CP-BM-2/67-2
(Determinationof watertransmissionunderpressure) as described by Taylor
and Holah(1996). The methodinvolvessealing a container ontothe floor
sampleand fillingit withwaterto a depthof 10 cm. After24 h the level of
wateris examinedto see if therehas beenany absorption into the surface. Ten
samples are assessed and all should pass the test (zeroabsorption)for the surface
material to be deemedsuitablefor use in foodfactorieswithrespectto water
absorption. Thistest is designedto assessthe uptakeof largequantities of water
(millilitres)into veryporousmaterials.It is not intended to assessthe small
waterabsorption of the wholematerial. Thisis measured by weighting floor test
plates (resin-based) or whole ceramictiles before and after having been
immersed in boilingwaterfor 2 hours.
The second test, a cleanability test, is basedon the methodusedby Mettler
and Carpentier(1999). Results of the latterstudy showedthat contamination
aftercleaningof flooring materials inserted in the floorof a cheesesite was
linkedto theircleanability and not to theirdisinfectability. That is whya tracer
of the microbial soil (a biofilm), sporesofGeobacillus stearothermophilus,
whichare not sensitiveto alkaline cleaning products, are usedto assess the
removal of the biofilm. One-day biofilms of Pseudomonas fluorescens
containing sporesof Geobacillus stearothermophilusare developedon test
Improving the design of floors 179