BLOCKS FLAGS AND KERBS – EFFICIENT DESIGN …

1 L534 November 2007 CUTTING PRECAST CONCRETEBLOCKS FLAGS AND KERBS EFFICIENT DESIGN ANDMANAGING THE RISKD ecember 2010 The Old Rectory, Main Street, Glenfield, Leicester LE3 8 DGtel: 0116 232 5170 fax: 0116 232 5197e-mail: is a Product Association of the British Precast Concrete Federation Ltd. 2010 BPCF effort has been made to ensure that thestatements made and the opinions expressed in thispublication provide a safe and accurate guide;however, no liability or responsibility of any kind(including liability for negligence) can be accepted inthis respect by the publishers or the PRECAST CONCRETEBLOCKS FLAGS AND KERBS EFFICIENT DESIGN ANDMANAGING THE RISKD ownloaded from AND CONTEXTD ownloaded from and contextInterpaveRISK ASSESSMENTS ilica is a natural component found in many constructionproducts. Crystalline silica is found in sand, sandstone, graniteand products such as concrete.

2 Health hazards can result frombreathing in the fine dust of crystalline silica. This can lead to thedevelopment of silicosis, a scarring of the lung tissue which canresult in breathing difficulties. Progressive silicosis is the morecommon form resulting from exposure over a longer following guidelines will help you eliminate this healthhazard when installing precast concrete paving BLOCKS , FLAGS andkerbs, either by removing the need to cut concrete products or byrecommending safer cutting practices and equipment . They donot replace the employer s legal responsibilities to ensure a safesystem of dusts, including respirable crystalline silica (RCS),carry a greater risk of ill health and have their own WorkplaceExposure Limits (WELs). Since October 2006 the WEL for RCShas been mg/m3. Exposures controlled to below this levelcarry a very low risk for developing silicosis.

3 Above this the riskincreases research has shown that cutting with a hand-held powersaw which lacks dust suppression produces a level of RCSexposure many times the WEL within seconds. Not only does thishave potential for the user to be exposed but also other innocentbystanders, such as work colleagues and the general research has highlighted the rapidly increasing dangers forthose who smoke and are exposed to respirable silica. In contrast, by using apower saw with watersuppression the operativewould require continuousexposure for some timebefore reaching themaximum allowablelimit. However, it isimportant to note that,even though theexposures are drasticallyreduced, the operativemust still wearrespiratory protectiveequipment for from assessmentInterpaveRemember that cutting KERBS , FLAGS and paving BLOCKS producesdust that: cannot always be seen can damage your lungs and cause health problems may affect workmates or members of the public standingnear you.

4 When planning work - Avoid cuttingMinimise cuttingControl dust generation during AMC Avoid, Minimise, , note that activities that could expose workers to silica aresubject to the Control of Substances Hazardous to HealthRegulations 2002 (COSHH). These Regulations require thehealth risk to be assessed and then prevented or controlled. Silicamust be controlled to an extremely low level (COSHH (workplaceexposure) limit of ). You are at risk if the dust youbreathe in over a full shift contains more RCS than the amountshown next to the penny!Photograph courtesy of the Health & Safety LaboratoryBLOCK PAVING1 or 2. Avoid or MinimiseCuttingDownloaded from pavingInterpaveThere are a number of techniques and products readily availableto help with the DESIGN of block paved areas, created withminimal or no cutting, including the following. Information onavailability of specific products and accessories is available fromindividual Interpave dimensions DESIGN and set-out the layout for pavedareas using modular dimensions (paving block width) and alsoapply them to penetrations or obstacles needed within the or restraint edgeManufactured half block2500mm nominal5000mmnominalNo cutting requiredManufactured closure unitKerb or restraint edge2500mm nominal5000mmnominalNo cutting requiredPREFERREDPREFERREDD ownloaded from pavingInterpaveClosure units with 45 herringbone, use manufactured units(known as Bishop s Hat or Mitre BLOCKS )

5 Instead of cut units tocomplete the laying of Laying Pattern careful consideration oforientation during DESIGN and setting-out can eliminate the needfor cutting, for example with herringbone pattern at 90 to edgesrather than the popular 45 , as shown BLOCKS use manufactured half BLOCKS instead of cut unitsto complete the laying pattern, for example as shown will be requiredat some boundaries5000mm Kerb or restraint edgeCutting will be requiredat all boundaries5000mm2500mmKerb or restraint edgeNOT PREFERREDNOT PREFERREDD ownloaded from pavingInterpave3. Control Dust GenerationDuring CuttingSelection of the right cutting equipment can minimise generationof crystalline silica dust and its availability for Splitting in many situations, block splitters cangive satisfactory results and do not disperse excessive Saws with Dust Suppression only bench power saws (nothand held) with dust suppression should be used for block from pavingInterpaveFLAG PAVING1 or 2.

6 Avoid or MinimiseCuttingThere are a number of techniques and products readily availableto help with the DESIGN of flag paved areas, created with minimalor no cutting, including the following. Information on availabilityof specific products and accessories is available from individualInterpave dimensions DESIGN and set-out the layout for pavedareas using modular dimensions (multiples of standard flag sizes)and select a flag size to Paving in-fills block paving can be used successfully tofinish the flag laying pattern in place of cut FLAGS , for example asshown above and Contour Changes where rapid changes in contour orlevels are needed, that require diagonal cuts, as an alternativeselect a smaller flag size or block paving, or redesign contours toaccommodate bigger concreteblocks as stretchersFour concreteblocks as headersKerbDownloaded from pavingInterpave3. Control Dust GenerationDuring CuttingSelection of the right cutting equipment can minimise generationof crystalline silica dust and its availability for Splitting for smallflags which can be manuallyhandled, block splitters can givesatisfactory results and do notdisperse excessive Saws with DustSuppression bench powersaws with dust suppressionshould be used for flag saw-cutting wherever larger FLAGS , use a hand-held power saw with dustsuppression.

7 Ensure that theflag to be cut is placed on afirm, level surface and that itcan be safely held in , use a thick timberboard or pallet to avoiddamage to the blade by thesurface below when cuttingthrough the flag. Do not cutflags placed directly on from concrete kerbsInterpavePRECAST CONCRETEKERBS1 or 2. Avoid or MinimiseCuttingAn extensive range of KERBS , channels and other components ismanufactured by Interpave members including those scheduledin the British Standard BS EN 1340 and specials for a variety ofapplications. In particular, small unit kerbing BLOCKS (as shownbelow) are well-suited to forming curves, corners and transitionswithout cutting. Consideration of all the product alternatives andsizes available and careful setting out can reduce or eliminate theneed for a hand-held power saw with dust suppression. Ensure thatthe kerb to be cut is placed on a firm, level surface and that itcan be safely held in place.

8 Preferably, use a thick timber boardor pallet to avoid damage to the blade by the surface below whencutting through the kerb. Do not cut KERBS placed directly on Control Dust GenerationDuring CuttingDownloaded from guidanceInterpaveGENERAL GUIDANCEFURTHERINFORMATIONIt is advisable to wash any residual slurry from the surface of theblocks, FLAGS or KERBS to avoid staining. Ensure that slurry wateror dried slurry cannot contaminate drains and that its disposal isin accordance with good site that cutting KERBS , FLAGS and paving BLOCKS producesdust that: cannot always be seen can damage your lungs and cause health problems may affect workmates or members of the public standingnear you. When cutting cannot be avoided it is important to damp down orextract the dust and you must always wear breathing , avoid cutting if possible, minimise the cutting if youcan t but always control dust generation if you AMC:Avoid cuttingMinimise cuttingControl dust generation during cuttingAs with all construction work, the appropriate personal protectionequipment (PPE) should be used.

9 Even with water suppressionyou will need to wear a suitable dust mask (respirator). Nuisance-grade dust masks do not protect your lungs. Use one with anassigned protection factor of at least 10, even when your watersuppression equipment is working effectively. Use either FFP3filtering face-pieces or orinasal respirators with P3 on PPE is available from HSE Leaflet indg174 (rev1) A short guide to the personal protective equipment at WorkRegulations 1992. Guidance is also available from Interpave onthe safe handling of precast concrete FLAGS (click here if on-line)and KERBS (click here if on-line) via Leaflet C100 Time to clear the air!, 2008 HSE Construction Information Sheet No 36 Revision 1 Silica, 2004 HSE Leaflet indg174 (rev1) A short guide to the PersonalProtective equipment at Work Regulations 1992 Control of Substances Hazardous to Health Regulations.

10 2002 Construction ( DESIGN and Management) Regulations. 2007 (CDM). Websites: Acknowledgements:Speedy Hire PlcProbst Handling and Laying Systems