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11/15/99 MON 10:22 FAX 9055700305 A-C-M <br />Et7tery - Lazar <br />Ease o,f cleaning pavers <br />4 <br />Al! paver praduccs wili i~}evitabty be affecced by general dirt, spiliages and tyre marhs an~ <br />will require frequent ckeaning. In the UK, the introduction of the Environmental Protection <br />?.ct in 1y91 set standards for eicantiness for town and eiry certres. Part of the Act called <br />ior designated areas to be cleaned and swept as much as six times a day_ <br />The extent and depth of stain penetration is affecred by the porosity of pavars. The ievel of <br />porosity of pavers is not normally specified and no mention of it apgears ia B.S_ 6;I7~14), <br />which sets out reyuirements for physical properties of canerete pavers. A typical vaiue for <br />tlie porosity of concrete pavers is around 3°6 and witl vary due to cement content, type <br />of ag~regate and additives used, ~vatertcement r~tia af mixes and surface cexture of the <br />paver produced. Experience has shown that seating pavers will reduce their porosity and <br />inhibic stain penetraisan. <br />ln the US~,, the Interlocking Concrete Pavement Institute ICPI [I1] has published a <br />comprchensiv~ guide deating with c(eaning and sealing of pavers and affirm that one of the <br />functionat adr•antages providad by sealers is that they can protect pavers frum srain <br />pertetration. , <br />Types of sealers available ~ <br />A range of water and solvent based po[ymer seaters is now available for use with concre~e <br />block paving, for improving the apgearance and performance of pavers. As block paving is <br />ca[egorised as a f~exib{e surface it is essential that the sealer ta be u~ed should also be <br />flexible. Three ty~es of seater are in general •use and may be characterised as follows: <br />(i) Water based emulsio~as <br />Water ~ased polymers are emulsions havin~ vecy small particles dispersed in water. These <br />reiy c~n penetration of solids in suspensioa inta thc sucface of pavers and intn rhe jainting <br />sand. Add;cionally, they rely on the ~vaporation of ti~e water to permit the gaccicles ro bind <br />with the concrete and sand. Whilst ehey wilt form a film on the surface of pavers, only a <br />weak bonding is achieved within the jainting sand due to the sotids being filtered ont. <br />~j o07 <br />Fig. Z- Sealing Pavers on petrot stakon fa~ecourt <br />