Pavingexpert - AJ McCormack and Son - Tarmacadam, Bitmac and Asphalt Pre-packs This page provides a general overview of the use of tarmacadam/bitmac in Britain and Ireland. The Laying Tarmacadam page looks at the methods used in constructing a tarmacadam footpath and an examination of the main layers within a pavement can be found on the Tarmacadam Construction page. Introduction Uses and Applications Tarmacadam, properly referred to as bituminous macadam or "Bitmac" for brevity, is often thought to be the cheapest method of surfacing a driveway or forecourt, but for smaller areas it can work out quite expensive, and the red tarmacadam can be more expensive than block paving. Tarmacadam has become a popular, although technically incorrect, term for both bitmac and for asphalt used to surface pavements, highways and even internal floors.

Note that the the term "Tarmac" ™ © ® is the name of a publicly listed company and they become annoyed enough to set lawyers upon those who take their name in vain and use it to refer to the material "tarmacadam", even though the name has entered the vernacular in the same was as, for example, "Hoover", "Biro" and "Sellotape". Throughout these pages, we have sought to use the contentious term as little as possible, preferring to refer to 'bitmac' or 'macadam' instead. Surfacing contractors normally charge by the weight or area of material laid, but for smaller areas, they may charge on a daywork basis that will include transporting the requisite equipment to the site. A typical surfacing gang of 4 men (1 x Rake-hand , 1 x Roller Driver and 2 x Labourers) will cost around £60-120 per hour + VAT. Bitmac is suitable for areas to be trafficked by vehicles, such as drives and forecourts, and can be used for paths, although we are not overly keen on using bitmac for garden paths.

The wearing/surface course (the uppermost surface) can be 'coloured' by using a coloured binder, often with coloured aggregates, or by incorporating coloured, coated chippings into a HRA wearing course. In general, all bitmac should be machine-laid by an paver machine except where it would be impossible/impractical to use a paver. Such exceptions include small areas (such as some private driveways), confined spaces and footpaths. On private works, the contractor will ascertain which is the most appropriate laying method to use. In most cases, the finish achieved with machine-laid bitmac is far superior to hand-laid material. Machine Laying Caveat All bitmac should be laid by a professional company as the tools and techniques are beyond the reach of most DIY enthusiasts. Accordingly, the methods outlined on this site are intended to give the casual reader a guide to good practice, rather than a step-by-step guide to laying bitmac. Beware of Cowboys! Armed with an understanding of how a bitmac pavement or highway should be constructed, you can check that the work being undertaken on your behalf is being done correctly.

This is especially important given the large number of 'tinkers' offering to lay bitmac at a discount price - they usually just throw down a thin layer of wearing/surface course, safe in the knowledge that they will be long gone in a couple of weeks when your new drive starts to fall apart! Beware of anyone knocking at the door offering bitmac 'left over from a big job down the road' - reputable contractors do not cold call to rustle up work! Definitions To try and clear up the confusion and get the terminology correct, here's a brief explanation.... Bitumen is a product of the oil-refining and petro-chemical industries. Very basically, it is the thick, sticky, residual goo that's left over when all the useful fuel oils, such as kerosene, petrol, diesel, etc., have been extracted by fractional distillation of a crude oil. Macadam is a process of binding together smaller aggregates, as pioneered by the legendary John MacAdam in the 19th century (although there are tales of the Chinese having used a form of "macadam" as far back as 3000BC). His work resulted in the development of tar-based macadams, which became abbreviated to Tar-mac.

Nowadays, we use bitumen from the oil industry rather than naturally occurring tar, and therefore we now have bitumen macadam or, as we call it in the trade, bitmac. Asphalt, according to British and European (CEN) definitions, is a mixture of bitumen and minerals. However, in the US, they use the term 'asphalt' for what we in Britain and the rest of Europe refer to as a Bitumen. This is the source of much of the confusion amongst non-trade professionals as to what's what and what's not. Asphalt Flooring So, when Americans talk of asphalt roads they do not mean roads surfaced with the hard, shiny, black floor covering found beneath the carpets in many newer houses, and, for American readers, when you hear about British and Irish homes having asphalt floors, this is not the same stuff as used to surface your roads and sidewalks. Confused? Good! Penetration Grades Bitumen, the binder used in Bitmac, comes in a range of "penetration grades".

There are specific tests that determine just what is the "penetration grade" of a given bitumen, but, rather than go into a lot of very technical and insomnia-curing detail, it is best to think of 'pen' as being a measure of "bitumen softness", of how far a point load will sink into a block of pure bitumen at normal temperatures. The pen grade of the bitumen binder has a direct bearing on the 'hardness' of the bitmac produced using that bitumen, and so we have a range of penetration grades, from 15pen, which is pretty damned hard, to 450pen, which is relatively soft. A 'softer', more pliable binder produces a softer, more pliable bitmac. Imagine trying to push the blade of a Phillips screwdriver into a bitmac surface; some bitmacs will offer far more resistance than others, and a lot of that difference is dependent on the 'pen grade' of the bitumen binder. So, some bitmacs are harder, or softer, than others, and the degree of pliability can be tailored to suit the requirements of the job in hand.

As a sweeping generalisation, the harder grades (70pen or less), are used as 'asphalts', while the softer grades (100 pen or more, are used as binders for bitumen macadams (bitmac). Bitumens of different pen grades can be blended to create binders with a specific pen grade. Cutback Under normal circumstances, a bitumen would need to be heated to relatively high temperatures (150°-180°C) to make it 'workable' on site. However, there are all sorts of reasons why such high temperatures may not be achievable or even desirable, the most common of which is that the mixed material will lose heat as it is transported from the batch plant to the site. And so, the bitumen technologists have developed what is known as "Cutback", a technique that renders the bitmac workable at lower temperatures for longer periods. This effect is achieved by 'doping' the bitumen binder with a lighter oil (often kerosene, creosote or similar), which acts as a solvent, retarding the setting process until it has evaporated.

There are different grades of cutback (you knew there would be, didn't you!) ranging from slow-curing, through medium-curing to fast-curing. Medium-curing cutback is a popular choice for hand-laid work, as it gives a good degree of workability for a reasonable amount of time, but still gives a trafficable surface in a matter of hours. Slow curing bitmac (aka Deferred Set Bitmac) is most often used by Local Authorities and the Utility Companies to effect minor or temporary repairs to roads and footpaths, because it can be stored in their depot or on the back of a normal wagon for several days, and then used as and when required. Once it has been compacted, it will achieve a degree of stability and be firm enough to carry traffic. This type of bitmac is the sort of stuff found in the 25kg packs of DIY/repair macadams sold in many Builder's Merchants. Fast-cure cutback bitmacs would normally be used in machine-laid projects, where a blast of additional heat from the Paver Machine will render the bitmac that bit more workable and easier to level accurately with the screed bar at the rear of the Paver.

"My drive was tarmacked some weeks ago but is still soft and tacky. Have I been swindled? See also the Tarmacadam Construction Layers page. The basic premise of a bitmac or asphalt surface is that the material is laid while hot and viscous, levelled and compacted as quickly as possible, and then allowed to cool so that it 'sets' and each particle is bound to its neighbours. Bitmacs with large aggregates (up to around 70mm) are used as road bases or base/binder courses, and the smaller aggregates are used for the surface layer, more commonly known as the surface or wearing course. The general principle is that progressively smaller aggregates are used from the bottom of the pavement up towards the top, as this helps to spread the loads imposed upon the finished pavement by vehicles or other road users.

Typical layers of a bitmac pavement Euro-names: During the recent review of British Standard 4987:Coated macadam for roads and other paved areas: Parts 1 and 2, the "Powers That Be", who wouldn't know which end of a tarmac rake to hold, decided that the terminology used for the layers of a tarmac surface are to be replaced as part of the ongoing 'harmonisation' with Europe. Road base is to become Base, while the base course becomes the Binder Course and the Wearing course is due to be renamed as Surface Course. In the long tradition of the UK and Irish Building Trade, we are totally confident that the older terminology will persist for many years to come. The photo opposite shows the various layers of typical bitmac surfacing. On the left, the carriageway comprises a barely visible Sub-Base, overlain by a Base, then a Binder Course and finally a Surface Course which brings the level up to that of the watermark on the kerbline. On the right, the footway is incomplete, and comprises (at this stage) only the Sub-Base and the Binder Course. The Surface Course was laid at a later date.

There are three main types of 'bituminous' surface; Hand Laid Bitmac, for domestic driveways, footpaths and other small areas Machine Laid Bitmac for larger drives, forecourts and roads Asphalt (SMA/HRA) machine-laid as a wearing course on public roads. [1] [1] - HRA on high speed roads is increasingly being replaced with SMA (Oh how we love these acronyms!) which is Stone Mastic Asphalt. This is a denser, tougher, more durable asphaltic material reinforced with fibres and has been shown to produce less traffic noise, much to the delight of the Highways Agency (HA). As with HRA, it must be machine-laid. Hand-laid 6mm dense bitmac Hot Rolled Asphalt with coated chippings Mostly used on roadways 10mm Stone Mastic Asphalt in red Photo by Dave L at RW Gale in Somerset Construction Construction of a bitmac pavement is dealt with on other pages. The various layers of a bitmac pavement are examined in the Tarmacadam Construction page while the working methods used in laying bitmac are described and illustrated on the Laying Bitmac Paths page.

Overlays As mentioned elsewhere, a wearing/surface course may be laid over an existing bitmac or concrete surface. This is known as an "Overlay". The overlay surfacing should be a minimum 25mm thick and MUST be bonded to the existing surface with a cationic or anionic bonding emulsion, commonly referred to as a 'Tack Coat'. Tack Coats Tack coat is a browny-black emulsion of bitumen that is applied to the prepared, existing surface before laying the new surface/wearing course. The emulsion bonds to the existing surface, and then the new wearing course will bond to the emulsion, ensuring full adhesion. It also helps ensure that water does not find its way between the new and existing surfaces where it can freeze and lift off the new surface. The tack coat is absolutely essential in almost all instances of overlay work, the only notable exception being where a wearing course is laid over a recently laid (ie, within the preceding 7-14 days) base course. 25 litre drums of Tack Coat Tack coat is typically spray-applied to the existing surface at the rate of 0.4 to 0.6 litres per m².

Some tack coats need to be heated prior to application; some are cold applied. On smaller jobs where a spray unit isn't feasible, the tack coat may be applied by a brush. The keys points are that the coverage should be complete, ie, no 'bald' spots, and there should be no pools of liquid on the treated surface. Tack coat 'breaks' (dries/sets/cures) in 10-15 minutes and is incredibly sticky when it does, so precautions may need to be taken to prevent operatives or vehicles crossing treated areas and picking up the bitumen emulsion as they pass. Laying The surface to be overlain must be clean and sound and free of organic material or other detritus. If the new material is laid over a badly cracked concrete base, old flagstones, or any other unsound base, any joints or cracks will soon be transmitted to the surface of the new bitmac, and the surfacing will fail. This phenomenon is known as "Reflective Cracking" and is a well-documented problem for all overlay surfacing, not just with bitmac, but with all other surfacing materials, such as concrete and resin-bound aggregates .

Any 'contractor' recommending an overlay of badly cracked concrete or old flagstones should be told to get back on his horse! It is important that any proposed overlay to a residential driveway will not raise the level of the surface to an impractical height, such as at garage door thresholds, and that it the new surface is at least 150mm below any damp-proof courses in the brickwork of the house or garage. It may be necessary to cut-out 'keys' at the thresholds to accommodate the new surfacing. Also, the level of any utility covers within the pavement being overlaid will need to be adjusted. These include water Stop Tap boxes, manhole and inspection chamber covers, cable tv boxes, etc. Unless there is a significant "lift" in level of 50mm or more, gullies, linear drains and the like are best left at their original level and keys cut around them, much as illustrated opposite for a threshold, and then the new surfacing is feathered-in to meet the original level. Pros and Cons As mentioned earlier, bitmac can be a cheap, reliable surface over larger areas.

Small areas can often prove quite costly as the 'set-up costs' of transporting a roller and other plant, an insulated bitmac wagon, and a laying gang account for a larger proportion of the overall cost. For residential driveways, it is often advisable to encourage a few neighbours to have their surfacing work done at the same time, thereby reducing the impact of the fixed, set-up costs. All bituminous materials will slowly degrade in UV light, which results in the binder becoming 'brittle'. This is the primary reason why older bitmac drives often have a crumbly appearance and the aggregate tends to be scuffed free of the surface quite easily. While there are some products that can 'rejuvenate' old, tired bituminous surfacing, (See Bitmac Cover-Ups ) they may not work too well on badly deteriorated surfacing. Modern binders are much more light-stable than those of just a few years ago and we estimate that a newly-laid bitmac driveway or pathway should give at least 10 years trouble-free service.

We know of bitmac driveways that have survived in excess of 30 years, and while they may be deemed adequate for a private householder who requires only a firm surface on which to park the car, their condition is generally poor and, in the public domain, they would be deemed unsafe and warrant immediate replacement. As bitmac is an oil-based product, spillages of light oils, petrol, diesel, paraffin etc. will dissolve the binder, and this dissolution can penetrate to a significant depth if left unchecked. The only remedy is to cut out the contaminated material and patch-in with new. See FAQ covering the replacement of fuel-contaminated bitmac on a residential driveway Bitmac, like concrete and other non-elemental surfacings, cannot be 'invisibly' repaired. Patching is the only solution, but will be obvious to the eye. If a sizable area is to be 'patched', it may be better to resurface the entire area, to maintain the pleasing appearance of a uniform surface. Untrafficked areas, paths and drives in shady and/or damp locations, and older bitmac surfaces are prone to moss and algae, which can become dangerously slippy.

This is the main reason why we NEVER recommend bitmac as a surface for garden paths. Surface vegetation is best removed by scrubbing with water, a general weedkiller and a stiff brush. Power washers can dislodge individual stones within the aggregate of an older bitmac surface and so should be used with care. Test out on a discreet corner before attempting to power-wash a larger area. Bitmac must be properly levelled and laid to adequate falls that will drain the surface water to a gully or other suitable drainage point. Whereas a machine-laid bitmac surface can be laid to falls as tight as 1:80, hand-laid surfacing is particularly prone to small low-spots, and, in order to avoid the puddles that seem to afflict so many bitmac drives, a fall of not less than 1:50 is recommended. Prices The price of bitmac or asphalt surfacing is somewhat volatile, to say the least. As the key materials are all oil-based, their price is largely determined by the price of oil, which has a habit of rising and falling in an unpredictable manner.

Previously, guide prices for various "typical" installations have been given, but in the wake of the roller-coaster oil price white-knuckle-ride of recent years, it has been decided to withdraw price information as it became impossible to ensure accurate pricing from one day to the next. However, surfacing contractors are usually happy to provide prices for any work and so it is recommended that you enquire locally. Construction Diagram StoneRoad Tarmac - Surface Types Surface Types Surface Types Bituminous Surfacing Materials There are several types of bituminous materials that can be used for roads, driveways, footpaths etc. Each has it's own specific quality for the use it is intended for; eg. drainage, wearing and or traction purposes among others. At StoneRoad Tarmac we survey each specific job and decide on the ideal material required. This will be explained to you by a member of our staff at the time of survey. Basecourse Mixes These materials are used to give a good firm surface on which to lay a wearing course material. They consist of a well graded large stone and dust mix which gives a good matrix. Held together by bitumen, this gives a well bound, dense material which is suitable for laying the wearing course on.

It is essential for all asphalt wearing courses to have a Basecourse Macadam because of the density of asphalt that provides ultimate endurance against wearing. This eliminates the risk of fragmentation which may occur when you do not lay the correct basecourse. It is not essential for all tarmac wearing course mixes, where a good stone foundation can also provide the base course required on certain jobs. For example: Household driveways, private roadways, play areas, tennis courts etc. This can be further explained at time of survey. Wearing Course Mixes - Macadams There are three main wearing course materials. 6mm, 10mm and 14mm, and all are used for specific jobs. Each mix can be individually tailored to your specific requirements, for example: where extra drainage is required an open texture can be specified which increases the amount of stone used in the mix. This will slightly reduce the durability of the surface but under some extremes may be necessary. The opposite of open texture would be dense texture where the specification would be to add in more fines, such as sand, stone dust etc. This creates a smoother more durable wearing surface than normal. Good all round drainage is essential in order to use this mix because it eliminates any water seepage.

Specification for 6mm wearing course:- This is a very fine mix which gives an excellent finish but does not have the strength required for heavy traffic and is therefore used mainly for footpaths, play areas and small household driveways etc. Specification for 10mm and 14mm wearing course:- These mixes are the preferred mixes for heavy traffic areas with each material providing an excellent finish coat and both having the strength and durability to resist wear by heavy traffic. 10mm is a particularly good finishing material when extra fines and bitumen are added. This mix is known as bungalow mix, highly recommended for household driveways because of its neat finish and durability. We will determine the right mix on survey after we have ascertained the amount of traffic in the required area. Wearing Course Mixes - Asphalt Specification for hot rolled asphalt:- This material consists of a high sand content along with a specific amount of stone held together with enough bitumen to give a well bound mix. Asphalt is a very strong material and is also extremely durable. It is used mainly on very high traffic areas where the addition of chippings can be used to give good skid resistance.

For example: Shopping centre car parks where there is a lot of twisting and turning and heavy load delivery vehicles, main motorways, airport runways etc. Designed for commercial use, not suitable where a neat finish is required. Specification for Marshall Asphalt:- Marshall Asphalt is a US designed material also known as American asphalt. A cross between normal asphalt and macadam this mix combines sand and dust along with a high stone content to give the durability of asphalt and the managability of tarmac. When used correctly creates the smoothest most durable surface possible for all types of commercial and residential jobs. For example: Household driveways and small to medium size retail premises. This material is currently being used on the runways at Dublin Airport. Extremely suitable where a neat finish is required. Laid with the latest machinery and quality workmanship, you can be assured of the perfect finish. Specification for SMA - Stone Mastic Asphalt:- A very durable mix which is also stable and resistant to deformation. A very high stone content gives excellent skid-resistance properties and also reduced noise levels. Surface water is also reduced due to the very high stone content which can be extremely useful on steep hills and level areas.

The mix is strengthened by the addition of dust and a very high bitumen content held in the mix by the use of fibres. A very popular material which has been used in America for over 20 years and is becoming increasingly popular in Ireland and the U.K. Additional information: It would be virtually impossible for us to list on paper all the types of tarmac and asphalt surfaces, there is endless variations of materials and mixes available. The most important thing is that you understand the basics and we hope we have provided you with a little insight to the way we at StoneRoad Tarmac take in choosing the right materials for your individual requirements. Remember the actual material and the way it is laid are the two most important factors when it comes to providing the perfect surface that you demand. Tar & Chip For a Tar & Chip finish hot tar is applied to a gravel base. Stone chips are thrown on top of the tar while it is still piping hot, so that they can stick to the tar. After the stone chips are laid on top of the tar, a steamroller is used to press them in firmly. The customer can choose from a variety of different stones and stone colors to achieve the look they want.

Below is a list of the sizes of materials generally used: 6mm Tarmac Tarmac Very pleased with the work. Attentive and respectful workmen. Would definitely recommend and use again! Mr T Reid Tarmac L. A. Kattenhorn & Partners Limited specialise in all sorts of tarmac works. It is a known fact that nearly all roads in this country are surfaced with tarmac. Tarmac offers good strength, durability and weather-resistance, ease of maintenance and repair, and neat, low-glare appearance providing good contrast to road-marking paint. This makes tarmac equally suitable as a surface for private drives, hard standings, car parks and parking areas for heavier vehicles and as a company we can takeout all works that involve this product. There is a wide variety of tarmac specifications to meet the broad range of their needs and use. We have been laying tarmac in the South since the company began. We only ever use chosen suppliers who specialise in the production of asphalt. These suppliers include Yeoman Asphalt with whom we have been working since our company started, Hansons, Wainwrights and Tarmac. We chose our suppliers based on location in comparison with the site of works and on their performance.

Drainage: Thanks to experience we will always try to provide suitable levels in order to ensure your drive or large area will drain properly avoiding the chance of puddling. We will ensure the area is dipped and create levels that will allow the water to flow to the suitable guttering or drain. Subgrade: The subgrade should be shaped to the falls required for the finished surfacing to ensure that the overall construction is of uniform thickness. Before final shaping, any weak areas of soft clay, peat or soil should be excavated and replaced with more suitable fill or sub-base material. If the subgrade is to be exposed for some time and particularly if it is clay, the question of protecting it against ingress of water should be considered. Failure to provide this protection can lead to a seriously weakened subgrade if wet weather is experienced during the work. Sub-base: The sub-base has two functions, one to provide a working platform for construction traffic and the other to increase the intrinsic strength of the construction. For parking areas which will carry only light vehicles there will be many situations in which a sub-base may not be needed.

On clayey soils which become sticky and soft then they are wet it is usual to provide a sub-base of a minimum thickness of 75mm. A greater thickness will be needed with subgrades susceptible to frost damage, where ground conditions are poor or where the parking area is to be used by heavier vehicles than private cars. The material should be spread, shaped and well compacted to provide an even surface to the required levels and falls. Base and Surface construction A selection of suitable tarmac materials for the construction of the base, binder course and surface course, together with recommended compacted thicknesses. Table 2 the construction for a permeable surfacing. Light usage, e.g. Private drives small office car parks Heavier usage, e.g. public car parks or areas where risks of indentation, tight turning or on thespot power assisted manoeuvring, or stray use by heavier vehicles are present Layer 30 A range of brand-named proprietary tarmac mixes is also available for car parking uses – details are available from individual tarmac producers or contractors ﻿﻿﻿﻿﻿﻿﻿Where tarmac is hand-spread in areas such as private drives and small car parks where the normal mechanical road paver is unable to operate more workable materials are necessary.

If an appropriate binder is not used there is a serious risk of marking, particularly in early life, which will be aggravated by heavy braking, on-the-spot wheel-turning, and heavy point loadings especially in warm/hot weather. ﻿﻿﻿Porous Asphalts are manufactured using either a penetration grade binder or for more onerous applications a Polymer Modified Bitumen. When hand laid, the resultant mixture requires suitable weather conditions and laying expertise to ensure it is spread and compacted to provide a resilient and durable surfacing. ﻿﻿﻿Where a Porous Asphalt is to be used for larger areas and/or heavier usage car parks, advice on suitable mixtures should be sought from the asphalt supplier. ﻿﻿﻿It should be borne in mind that off-road vehicles and the heavier types of car, e.g. people-carriers, may impose higher stresses on the surfacing than normal private cars as will on the spot turning using of power steering. Therefore the use of more specialist materials is required and advice should be sought from a professional contractor or direct from an asphalt supplier. ﻿Surface course materials are available to give a coloured finish where required, although these are always very high in price.

﻿ Laying Satisfactory performance of the construction will be obtained only if all layers are adequately compacted. Compaction should be undertaken with a minimum six-tonne deadweight roller or an equivalent vibrating roller. The asphalt layers must be compacted while the material is at an appropriate temperature. Recommendations for temperatures and for laying and accuracy of finish for asphalt construction materials are given in BS 5949879. For Porous Asphalt recommended temperatures for laying and compaction should be obtained from the material supplier. In view of the skill needed in laying asphalt materials, particularly those required for the permeable surfacing option, it is strongly advised that laying be entrusted to experienced specialist surfacing contractors for example members of Mineral Products Association or their sub-contractors.

Contact Us/ tarmac - definition of tarmac in English | Oxford Dictionaries Definition of tarmac in English: tarmac noun trademark in UK 1[mass noun] Material used for surfacing roads or other outdoor areas, consisting of broken stone mixed with tar: [as modifier] ‘the tarmac path’ More example sentences ‘The surface of the road is made up of a surface layer of tarmac, approximately 4 to 6 inches thick followed by a concrete layer of approximately 12 or 13 inches.’ ‘A decision to replace a paving stone surface in historic Corsham town centre with tarmac in a road safety scheme may be reversed.’ ‘You won't end up wondering what it must have been like 100 years ago because, apart from tarmac road and the other tourists, it's still exactly like it was.’ ‘A third alternative would be to surround the skateboard area with paving slabs and create access from the main tarmac path to the facility with minor repairs to the surface of the car park.’ ‘Many bridleways were closed for many months following the outbreak of the disease, and riders had to exercise their horses on private land where they were grazed, or hack out on tarmac roads.’ 1

.1the tarmac A runway or other area surfaced with tarmac or a similar material.

Example sentences ‘A healthy baby boy was delivered in the back of the helicopter on the tarmac at the Comoro Airfield.’ ‘Waiting on the tarmac at Mehrabad Airport to board the flight that would take me south to Kerman, on the dusty edge of Baluchistan, I studied the plane.’ ‘Eyewitnesses reported that one of its wingtips hit the tarmac and the jet crashed through an airport fence and then exploded.’ ‘Five minutes down the tarmac and we take an open and contouring track south-east.’ ‘Instead of taking off, however, the plane and its passengers sat on the tarmac in a weather delay for four hours before returning to the terminal.’ verb Which of the following is correct? Rifles became breach-loaders Which of the following is correct? Let's prevent security breeches Which of the following is correct? The sea made a breach in the wall The sea made a breech in the wall Which of the following is correct? He brushed the dirt off his breaches He brushed the dirt off his breeches Which of the following is correct? The vault was breeched with dynamite The vault was breached with dynamite Which of the following is correct?

The rifle was a breach-loading one The rifle was a breech-loading one Which of the following is correct? They're breeching company law Which of the following is correct? There were some bad breeches of etiquette There were some bad breaches of etiquette Which of the following is correct? He promoted the breech-loading shotgun He promoted the breach-loading shotgun Which of the following is correct? I put on my breaches I put on my breeches You scored /10 practise again? Retry Paving Expert - AJ McCormack and Son - Laying Tarmacadam Drives and Paths Timber edgings Sub-base Once the concrete haunching to the edgings has set (usually at least 24 hours) the sub-base material will be placed (if not already in place), levelled out with shovels and/or rakes, topped-up as and where required, and then be compacted with a mechanical roller. Some smaller jobs may use a vibrating plate compactor to consolidate the sub-base, but, as a roller is essential for later compaction of the bitmac layers, there is normally one available on site and besides compacting the sub-base much more thoroughly than many plate compactors, they are considerably faster. Rake and Roll!

Sub-base is spread and raked to level... ...before being compacted using a heavy roller The accuracy of the sub-base layer will be checked at regular intervals by placing a straight-edge timber from the road kerb to the edging kerb and 'dipping' - measuring the distance between base of straight-edge and the consolidated surface of the sub-base. For most jobs, the sub-base is expected to be accurate to ± 10mm. Although a tape measure can be used to check the 'dip', we find that technique requires far too much bending to read the tape. A noggin of timber cut to the required depth (in this example, 75mm) can be fastened to the base of the straight-edge and used to judge the dip - if the sub-base is too high, the ends of the straight-edge won't sit on the kerbs; if too low, the noggin will be carried above the surface of the sub-base. A quick word about Regulating Quite often, a surfacing job will involve laying over an existing substrate. When this is simply a matter of laying a new surface course on top of a pre-existing pavement, this is known as an Overlay .

However, on some jobs, the levels of the existing surface may be low and will require 'building-up' to bring the levels within tolerance. When a contractor is required to lay, say, 30mm of 10mm SMA surface course, there is no extra paid if 40mm is laid. The contractor is expected to ensure the levels of any sub-layers are as close to the required level as is possible, and to notify the client of any variation before laying the surface course. To ensure the layers of macadam or asphalt are as close to specification as possible, and that there is no needless over-use of material, a contractor may find it necessary to "regulate" one or more of the sub-layers. Regulating involves building-up sub-layers using additional material as and where required. Build-up is always done using the cheapest suitable material. Sub-bases will be regulated with additional sub-base material, while base and binder courses would be regulated with binder course material. The aim is to keep costs to a minimum, and to lay the most expensive material, which is always the surface course, as close to the specified depth as possible.

Regulating may involve laying 10-30mm of additional material over an existing sub-layer. Occasionally, large areas will require regulating by laying a variable depth of additional material over the entire area, but in most cases, regulating will involve build-up in discrete patches that will, eventually, be covered and hidden forever by the subsequent upper layers. It's not always necessary, but when it is, good regulating saves money. It make best use of the available specified materials and ensures a good quality pavement is constructed without unnecessary wastage of the more expensive materials. Regulated sub-base minimises over-use of binder course Regulated binder/base reduces over-use of surface course Binder Course The binder course is the first of the two bitmac layers used in a typical footpath or residential driveway. The aggregate in this type of bitmac is chunkier than that used in the surface course, a typical size being 20mm. The binder course material is delivered to the site in insulated wagons which keep it hot, and it is then laid as quickly as possible, before it becomes too cool and becomes unworkable. The type of job normally dictates how the bitmac will be laid.

If being machine-laid, the delivery wagon empties the bitmac into the paver machine as it progresses along the run. The paver machine re-heats the bitmac before spreading and screeding it level in one continuous operation. Paver machines lay binder course where possible Note how hopper sides 'lift' to force bitmac into centre One hand-lay jobs, the bitmac is normally treated with an oil-based compound known as cut back that helps to keep the bitmac workable for longer at lower temperatures. The bitmac will be tipped off the delivery wagon onto a clean surface, such as the existing roadway, and then sheeted over with large tarpaulins that help retain the heat. A JCB or other Loading Shovel may then feed the bitmac to the laying gang, tipping it out as needed to each section of path, where it is raked level by the rake-hands who use their skill and experience to judge the accuracy of level.

Rakes and shovels take over in more inaccessible areas On smaller jobs, it may not be feasible to use a Loading Shovel and so the bitmac may be manually shovelled from the sheeted pile into barrows and then wheeled to the laying edge by the labourers who tip it out where it is needed as directed by the Rake-hands . The carrying bucket of the Loading Shovel or the skip of a wheelbarrow will be 'painted' with red diesel (fuel-tax exempt and so relatively cheap) as this helps prevent the hot bitmac sticking to the cold metal and building up over time into a solid, immovable mass. Similarly, the rakes and shovels will be occasionally dipped in diesel to help prevent the bitmac sticking and the Rake-hands like to keep their tools hot, heating them over a flame at the back of the paver machine or over a fire-bucket, as this too helps keep them from becoming clogged and unmanageable as the bitmac cools. Heavy rollers compact the bitmac while it is still hot Vibrating plate compactors may be used in awkward areas The binder course is rolled as soon as it is laid.

It will take at least half-a-dozen passes with the roller to consolidate the still-warm bitmac. To prevent the bitmac sticking to the roller, water is continually dripped over the drums from an on-board storage tank. This is the cause of the steam often seen rising from freshly-laid bitmac and asphalt surfaces. Vibration is rarely used when rolling hot bitmac/asphalt. Be aware that rolling and compaction is very noisy work. Until you've witnessed the compaction phase of blacktop construction, it can be difficult to appreciate just how much of a din is made by all the heavy kit. It may be a good idea to forewarn neighbours and to keep sensitive pets well out of the way. For the binder course, the roller driver will continue rolling non-stop until there are no roller marks in the surface. When compacted, the finished level of the binder course is required to be accurate to around ± 10mm. Surface Course Finally, the Surface Course is laid. This is usually done immediately following completion of the binder course, but on larger projects, it may be the following day or later in the week before this task is undertaken.

On some projects it may be several weeks or months before the final layer is placed: a good example would be the access roads on a new housing development. The surfacing contractor will lay and compact a base and/or binder course which will be used as a running surface while other construction work takes place on site. Insulated delivery wagon tips bitmac into hopper of paver machine. Both vehicles travel safely over the new base/binder course. Sealing grit applied to new estate road This running surface may be coated with a 'Sealing Grit', a bitumen-coated fine aggregate (3 - 0mm) with low tackiness, which is used to fill any voids in the surface and so prevent them filling with undesirable detritus, and to reduce the initial tackiness of the new surface. Once construction work is completed, the running surface can be cleaned and repaired or regulated as necessary before the final surface is laid. The sealing grit will, hopefully, have helped preserve the bitmac surface while it awaits its top course. The surface course material contains much smaller aggregate than the Binder Course, intended to give a finer, smoother finish.

The surface course is laid in much the same way as the binder course, except even greater care is taken with levelling as this is the final layer and will need to be accurate to around ± 6mm. Machine-laid surface course material is accurately levelled as a matter of course, but with hand-lay jobs, the Rake-hands will often use a 'Lute' (has no teeth, gives smoother finish to dense wearing courses) to spread and level the wearing course material, especially when working with Dense material . Hand laying surface course Completion and Making Good The newly laid bitmac can be walked upon immediately after rolling. For residential driveways, it is often wise to allow at least an hour or so for the surface course to completely cool before trafficking with vehicles. Most contractors would prefer vehicles to be kept off the newly completed surface for 24 hours, and this is generally good advice. Also, it should be noted that with driveways, extra care should be taken with cars and other vehicles for the first week or so, especially if a "cut-back" surface course has been used.

Wheel spins, sudden acceleration or deceleration, and sharp turning at speed or "on the spot" can scuff or "tear" the wearing course. It can be impossible to invisibly repair such scuffing, and no contractor is likely to accept any liability for damage caused in this way. Finally, the site should be cleaned and cleared of all detritus, dregs, bits of spilled or surplus bitmac, and any other construction materials. The haunching to edging kerbs should be covered over with topsoil, turf or other suitable material, taking care not to contaminate the new surface. Completed bitmac footpath On wider jobs, it's often possible to spot the 'seams' formed by individual passes of the paver machine Making good to the soft-landscaping (lawn, garden, etc) is often a source of problems on private driveway projects. Many of the better blacktop gangs do not undertake soft-landscaping. They are often brought in to lay the 'mac and any restoration or making-good is left to another contractor. However, some gangs do offer a full service and will re-lay lawn or make good to planter beds that may have been disturbed during construction works.

So, it is a good idea to establish beforehand just what services will be provided by the contractor, to ensure there is no misunderstanding or ill-feeling at the end of the job. Which raises the issue of just when should any 'making-good' take place? Many blacktop contractors would be less than happy at the thought of their freshly laid blacktop being sullied by some gardener bringing in topsoil or plants, which inevitably dirties the surface and can be hard to clean. Accordingly, some of the better organised projects see the soil and other softscape requisites brought into the site before the final surfacing is undertaken, even though it means stockpiling the materials until the surfacing is complete and the 'making good' can be effectively completed without the need to traffic the new surfacing. Other Tarmacadam resources on this site...

Question: What is the fuller name of the road surfacing material, tarmac?
Answer: Tarmacadam