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11/15/99 MON 10:21 FAX 9055700305 A-C-M
<br />Emery - l.azar
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<br />1. Ingress of moisture through block paving can have a marked effect upon che struccural
<br />performance af the pavement
<br />2. Under an adverse combination of water, material and [raffic, a concrete block
<br />pavement can develop significant levels of nitting after a few thousand 5000 kg scandard '
<br />axles, even though the requirements of BS 7533 [6] are satis~ed ~ '
<br />3. The application of a poiymer sealer to a fully granutac concrete block pavemenc can
<br />resul~ in a significant improvement in pavement performance.
<br />In-situ in~ltration tests by Emery [7j, using a 140 mm dia. fallin~ head permeame~er, on
<br />an area of unsealed pavers have shown that, in simulated flood conditions, i.e. with a depch ~
<br />of standing water of approx. 40 mm, the in~ltration rate was 300 mL/sec. This equaces to '
<br />approximately 1000 litres of water penetrating one square meae of pavers in one minute.
<br />For sealed pavers under similar conditions the infiltration rate was 15 mL/sec. •
<br />Laboratory research by Shacket (8J, in which he simutated rainfall of apprax. 45 mm per
<br />hour on newty laid block paving, indicated thac up to 65% of the rainfall peneqated the .
<br />joinu of the pavement. On block paving, sealed with a water based acrylic sealer, he
<br />concluded that infi(tration could be reduced by about 50°.b.
<br />The foregoing corroborates the assertion that sealing of pavers will diminish the ingress of
<br />water through paver joints.
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<br />Strengthening of pavements
<br />Recent work by Knapton & Algin [9] : provides a mathematical approach to the .
<br />understanding of the concept of interlock. It confirms the importance of maintaining sand ~
<br />between joints throughout the tife of a pavement surfaced with pavers to transrnit shear
<br />stresses between neighbouring pavers. This, they conclude, ,may be achieved by jointing
<br />sands being treated with pre-polymer liquids. ~
<br />Prevention of infiltratian of fuels, through jaints
<br />Concerns have been expressed by Petroleum Of~cers tha[ ingress of fue[s through joints ~
<br />may present a potential hazard if fue[ accumulates in the laying course sand.
<br />Environmental Agencies have also stated that~there is a risk of contamination of underlying "
<br />water supplies if fuel and other,potlutants aze allowed to,pass through a pavement. These
<br />matters have been addressed by,Emery [7j,in~a previous paper. His conclusions are: -
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<br />(a) Paved forecovrts which~have not been sealed may give rise to~unacceptably high -
<br />'Lower Explosive Levels'. ~ . -.
<br />(b) Sealing of concrete blocks reduces infiltratioa of water and fuel spiliages to an
<br />insignificant levei. -
<br />Many petrol station forecourts in the UK, surfaced with cancrete blocks, aze now sealed on
<br />instructions from Petro(eum Officers. Figure 1 shows sealing work being carried out ac a
<br />rypical petrol station forecourt.
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