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11/15/99 MON 10:20 FA% 9055700305 A-C-hi
<br />Cmery - Lazar
<br />I~j oos
<br />2
<br />Four forms of joincing sand erosion were identified by Ernery j2] and he developed a!ow
<br />viscosity pv(ymeric seater tfl counceract these erosion probiems. Besides stabilising the
<br />jointing sar~d, the sealer afso; . .
<br />• Screngchens pavemencs
<br />• Resists penetration vf water and fuels tl~rough paver joincs '
<br />+ Resists stain p~netratlon and weed growth in joints '~
<br />'Vt~hy seal pavers?
<br />(t is che authors` contention that sealing concrete black paving witl provide the bene~ts ~.
<br />discussed below. Of course, there are situatians where the exclusion of warer from the
<br />pavement consuvciion may be unimportant. Indeed, there aze proje~ts where poraus pavers
<br />are necessary for reducing runoff and repJenishment of aquifers and sea{ing would
<br />therefore be inapprvpriate. .
<br />Retention of sand irt,jvints
<br />Block paving provides~ perhaps, the most durabie form of surfacing for any flexibie
<br />pavemenr. Its unique self-articuiating suncture wil( normally not require expansion joints •
<br />and may effe~tively be used on domestic driveways and aircraft pavements using virtualiy
<br />che same simpie canstruction methads. However, to provide and maincain interlock, -
<br />defined by Knapton[3] as "...the inability of an individual paver to move indegendently of
<br />its neighbours", it is essential to retain sand in joints., ., ,. ,
<br />The fQUr fQrrns of ~oincing sand ecosion identified by Emery j2] are:
<br />ti) 1er blast a,rrd prapeUer wash frorn aircraft engines
<br />(ii) (1se af vacw.rm sweepers and high pressure cleaners ~'
<br />(iii} High velacity warer flow
<br />(iv) 13egradation and pumping of laying course rnaterials '
<br />A wide ranging report on the wvr[dwide us~ of pavers for aircraft pavements has been '
<br />prepared by Knapton and Emery for the UK Civil Aviacion Autt~ority CAA [4}. ~ Among ~
<br />che recommendacions given in this report is that ero5ion of jointing sand by jet biast sllould
<br />be minimised by use of joint stabiiisir-g material, i_e_ sealers.~ ,
<br />Vacious materials were used by Emery to overcome jointing s~.nd erosion, son'ie of which '
<br />grvvided only a temporary sotution to the problems. The mosc effective means of sealing ~
<br />and stabilising jo'snting sand was found to be a specifically ~ormulated, clear liqnid ~
<br />urethane pre-polymer that retains a high ievel of elasticity after polymerisation.
<br />~ii i~~.~; , _~!~,~ ~ ~ . "
<br />Preventinnofingressofwatertltroughjoints.,,.:~,,;,,,,;,; ,,; ;,~ ,
<br />An essential requirement aF inast pavement,surfaces is to exclude wacer from the ~
<br />underlying pavement surface. That 5% of a paver, surface is made up of joints, makes the
<br />Iikelit-ood uf infiltzation of water inevitable unless some form vf sealing is provided. ~
<br />Iavestigations by Knapton [57 into the effects of .water peneuating concrece block gaving
<br />concluded that: ~ ~ ~ ' ' , ' ~ . , . .
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