THIS IS A LIST OF WIDELY VARYING ITEMS THAT WILL GIVE YOU A GUIDE TO SURFACE DRESSING
This is an
interesting list of many items related to surface
dressing, and by using the search / find function in your
browser you should be able to locate information
particular to your needs, it will probably be of most
benefit to those who already know a little about the
subject but wish to increase the depth of their
knowledge.
However if you are new to surface dressing you will
probably find it more rewarding to first read the,
"Practical Guide to Surface Dressing" page,
which can be accessed by pressing,-------> HERE
There is a
"Picture Guide to Surface Dressing", accessed
by pressing, -----------------------> HERE
Additional items were
placed on this page on 12-06-2008
BASE VISCOSITY - SURFACE DRESSING BINDER
This term refers to the original binder that is used as the "base" of the binder formulation, whatever purpose the binder is being formulated for.
It is IMPORTANT to be aware of this basic idea, but binder technology is very complex, even BASE binders with the SAME viscosity can have different BINDER properties.
This knowledge is outside the realm of most engineers and also outside the knowledge of most "salesman" selling "new and improved binders", ask for specific information
Refer any information / specification / sales "blurb" to your Materials Engineer / Materials Consultant for advice or comments they may wish to make.
The above comment also applies to any "modified" binders you may be considering using.
There are other pages in this database that will refer you to written reports on various binder properties, just use the "Query" or "find" functions and a suitable "key word" to create a list of items referring to binder.
See also:-***KI-70***SPRAYING VISCOSITY***BS 3690***
BINDER SPRAYER SPEED - SURFACE DRESSING - RATE OF SPREAD OF BINDER
I personally regard this as the single most important factor affecting the success or failure of SURFACE DRESSING and one that is least checked.
A 10% ERROR IN SPEED IS THE SAME AS A 10% ERROR IN THE RATE OF SPREAD OF BINDER, THINK ABOUT IT!
When was the last time you checked the speedometer of the sprayer.
And it's not a bad idea to check that you have the correct speed chart with the sprayer, you may scoff but using the wrong chart has happened I can assure you.
See also:- ***BS 1707***BINDER SPRAYER SPEED CHART***
BINDER SPRAYER SPEED CHART - SURFACE DRESSING
Although very modern BINDER SPRAYERS have "high-tech" control panels for the control of BINDER spray rate it is still more usual for each sprayer to have a BINDER SPRAYER SPEED CHART specific to that machine.
The thickness of the BINDER film sprayed on the road surface is dependent on the forward speed of the BINDER SPRAYER, and the rate at which binder is sprayed from the spray bar, determined by the DEPOT TRAY TEST.
It does not hurt to check, AT THE BEGINNING OF THE SEASON, that the BINDER SPRAYER has the correct speed/rate of spread chart, so that the correct forward speed can be determined for a particular spray bar discharge rate, i.e. amount of binder actually sprayed per square metre.
See also:- ***BINDER SPRAYER SPEED***BS 1707***DEPOT TRAY TEST***
BINDER TRAY TEST - SURFACE DRESSING - RATE OF SPREAD OF BINDER
This simple little test is used for assessing the SURFACE DRESSING BINDER RATES OF SPREAD ( see this item in the "Practical Guide" ).
A number of trays (usually the biscuit tin lid type, or similar) are placed diagonally across the path of the binder sprayer. the spray-bar operator will raise the "skirt" on the spray-bar just sufficiently to avoid the trays and the sprayer will pass over them during his spray run.
The trays are lifted and weighed and the rate of spread calculated. This is easily done by knowing the original weight and area of the tray.
A particularly simple and efficient way of doing this test is to use small paper (plastic melts) carrier-bags to put the trays+binder in and use a hanging spring balance to conveniently weigh it.
You usually find the weights of the carrier-bag plus the empty tray are remarkably constant so that you can easily (for practical purposes) determine the weight of the binder deposited on the tray and by the use of a predetermined multiplying factor instantly obtain the rate of spread of binder per square metre.
Charts of found binder weights against rate of spread per square metre can easily be created.
I'm afraid you will have to work your own conversion charts out according to the area of the trays you use!
This test has largely been replaced by the Carpet Tile Test, using standard absorbent pads, they may be "tiles" cut from carpet.
See also:- ***CARPET TILE TEST***
BS 1707 - SURFACE DRESSING BINDER SPRAYERS
BS 1707 : Hot binder distributors for road surface dressing.
This document specifies the criteria a BINDER SPRAYER must comply with, and sets down test procedures to ensure this compliance.
These test procedures include the DEPOT TRAY TEST, and the CARPET TILE TEST.
A DEPOT TRAY TEST will determine the uniformity of transverse distribution of the spray bar and just as importantly the rate of delivery per minute of the BINDER SPRAYER.
The rate of delivery of the BINDER SPRAYER must be known to determine the forward speed of the BINDER SPRAYER.
The CARPET TILE TEST is an on site test to determine the actual amount of binder being sprayed on the road, across its complete width.
Carpet tiles are not often used but have been replaced by large bitumen absorbent "paper" squares.
The on site BINDER TRAY TEST is also a commonly used form of the CARPET TILE TEST the principle being the same, but you use small trays instead of absorbent paper squares.
See also:- ***BINDER TRAY TEST***CARPET TILE TEST***DEPOT TRAY TEST***CONE TEST***BINDER SPRAYER SPEED***
BS 63:PART 2 - SURFACE DRESSING CHIPPINGS - AGGREGATE
This standard used to cover the GRADING and FLAKINESS specifications for SURFACE DRESSING CHIPPINGS, it also included dust content requirements.
It has now been superseded but is still often referred to because of its more understandable presentation.
This standard is now superseded by BS EN 13043, and was withdrawn in June 2004.
BUT dust contents are often over-ruled by tighter specified dust contents in the contract document of the specifying authority.
See also:- ***SURFACE DRESSING CHIPPINGS***BS 63:PART 1***SURFACE DRESSING CHIPPING DUST CONTENTS***BS EN 13043***PD 6682-2
BS EN 13043 : 2002 : Aggregates for bituminous mixtures and surface treatments for roads, airfields and other trafficked areas
This standard supersedes BS 63, Parts 1 & 2, which was withdrawn in June 2004.
This standard specifies the properties of aggregates and filler aggregates obtained by processing natural or manufactured or recycled materials for use in bituminous mixtures and surface treatments for roads, airfields and other trafficked areas.
PD 6682-2 : 2003 : Aggregates - Part 2 : Aggregates for bituminous mixtures and surface treatments for roads, airfields and other trafficked areas - Guidance on the use of BS EN 13043
Part 2 of this Published Document (PD) gives guidance on the use of,
BS EN 13043 : Aggregates for bituminous mixtures and surface treatments for roads, airfields and other trafficked areas, in the UK.
This document had to be produced because it is so difficult to understand BS EN 13043 : 2002, but is only marginally less difficult to comprehend, in my opinion.
BS EN 12271-3 : 2002 : Surface dressing - Specifications :
Part 3 : Rate of spread and accuracy of spread of binder and chippings
BS EN 12272-1 :2002 : Surface dressing : Test methods :
Part 1 : Rate of spread and accuracy of spread of binder and chippings
BS EN 12272-2 : 2003 - Surface dressing - Test methods - Part 2 : Visual assessment of defects
This standard is applicable to all surface dressings (roads, airfields and other trafficked areas) and specifies qualitative and quantitative methods of the visual assessment of defects of surface dressing.
BS EN 12272-3 : 2003 : Surface dressing - Test methods - Part 3 : Determination of binder aggregate adhesivity by the Vialit plate shock method
This standard specifies the measurement of the binder aggregate adhesivity, and the influence of the adhesion agents or interfacial dopes on adhesion characteristics as an aid to design binder aggregate systems for surface dressing.
It is not intended that this method is used on site for quality control.
CARPET TILE TEST - SURFACE DRESSING - RATE OF SPREAD OF BINDER
This is a more sophisticated form of the on site BINDER TRAY TEST to determine that a surface dressing binder sprayer is spraying at the correct rate, it is fully covered in BS 1707.
The principle is the same as the on site BINDER TRAY TEST, but with "carpet tiles" , they are not often actual carpet tiles but more often specially absorbent paper squares, being laid COMPLETELY across the width of the area to be sprayed, i.e. the wheels of the sprayer can pass over them (in theory), this not being possible with shallow tin trays/lids.
The sprayer then makes a pass whilst spraying over the paper squares, they are then taken up and weighed.
With these weights it is then possible from tables to calculate the rate of spread of binder in litres per sq. metre.
It is also possible to check that rate of spread of binder is uniform across the sprayed width.
It is MOST IMPORTANT when carrying out either a CARPET TILE TEST or an on site BINDER TRAY TEST to know ACCURATELY the speed of the BINDER SPRAYER.
It is most important to know the RATE OF SPREAD is correct at a particular speed.
See also:- ***BINDER TRAY TEST***BS 1707***
CONE TEST - SURFACE DRESSING - TRANSVERSE BINDER DISTRIBUTION
This is a simple but effective test to determine that the jets of the binder sprayer spray bar are operating more or less correctly.
For truly accurate testing of spray bar performance a DEPOT TRAY TEST is necessary.
Basically the binder sprayer is positioned on a clean piece of road and the two outside spray bar jets are switched on for a set period of time, the binder sprayer is moved forward a little, the outer jets are switched off and the next two jets turned on, the jets are switched on for an equal length of time.
The process of testing just two jets at any one time and moving along the bar from the outside and each time moving the binder sprayer forward results in a "cone" being produced on the road, visual inspection of the cone will pick up any serious defects with any of the jets and therefore the transverse binder distribution.
See also:- ***DEPOT TRAY TEST***CARPET TILE TEST***
CSS ENG/3-94 - POLYMER MODIFIED BINDERS FOR SURFACE DRESSING
The purpose of the report is to investigate the use and performance of polymer modified binders used in surface dressing.
It is an informative report and well worth reading.
See also:- ***TRRL PROJECT REPORT 12***MODIFIED BINDERS***
CSS ENV/5-93 : CODE OF PRACTICE FOR TRAFFIC CONTROL OF SURFACE DRESSING OPERATION
A comprehensive amount of information on the subject is contained in this report.
This code is produced by the COUNTY SURVEYOR'S SOCIETY (now the CSS), and copies could be obtained from :-
Lisa Tuck, Dorset County Council,
Transportation & Engineering Dept., County Hall,
Dorchester,
Dorset,
DT1 1XJ
Note : This document has been superseded, see the following item, this information is retained for reference purposes.
See also:- ***SURFACE DRESSING, TRAFFIC SAFETY AND CONTROL***
CSS ENG/3-2000 : RSDA / CSS Code of Practice for Signing at Surface Dressing Sites
This code is published jointly by the Road Surface Dressing Association and the CSS ( formerly the County Surveyors Society ).
It has been designed in accordance with the principles set out in, Chapter 8 of the Traffic Signs Manual, but is not meant to supersede any part of Chapter 8.
Copies are available from :-
CSS, Derbyshire County Council, Environmental Services Department, County Hall, MATLOCK,
Derbyshire, DE4 3AG ------------ Tel. and Fax. Matlock, 01629 585730 (CSS office)
DEPOT TRAY TEST - SURFACE DRESSING - RATE OF SPREAD OF BINDER
The DEPOT TRAY TEST is fully described in BS 1707
The test involves locating the binder sprayer spray bar over a large test tray, the length of the spray bar, which is split longitudinally into 50mm. wide sections, then the spray bar is run for 60 seconds at correct and known binder temperature and tank pressure.
After the 60 secs. each separate tray is dipped and recorded, all these dips are recorded and transverse distribution, (evenness), of the spray-bar is worked out.
Also from the figures the total output of the spray-bar per minute is calculated, this is very important in determining forward speed of the sprayer.
The rate at which binder is spread on the road is determined by forward speed of the sprayer and rate of delivery from the spray bar.
See also:-***BS 1707***BINDER SPRAYER SPEED***BINDER SPRAYER SPEED CHART***
DTP ADVICE NOTE HA 33/86 - MODIFIED BINDERS FOR SURFACE DRESSING
This ADVICE NOTE is a very interesting NOTE on modified binders for use in SURFACE DRESSING.
It raises such points as:-
(1) justification of increased cost
(2) what are the benefits
(3) what is exactly in the modified binder
(4) how can we test the product to see if it conforms to the manufacturers specification.
(5) what effect the length of storage, and storage temperature has on the binder modifier
I would recommend anybody considering using a modified binder to read this ADVICE NOTE.
This is NOT a condemnation of MODIFIED BINDERS some are excellent products, but a knowledge of their costs, benefits, problems and whether they are necessary can be assisted by this ADVICE NOTE.
It is superseded by DTP DESIGN MANUAL HD 31/94.
See also:- ***MODIFIED BINDERS***INVERTED BREAKING***
DTP DESIGN MANUAL HD 37/97 - SURFACE DRESSING
This part of the DESIGN MANUAL FOR ROAD AND BRIDGES includes information on SURFACE DRESSING, it contains excellent information on the subject and is recommended reading.
Full title :- Volume 7 : Pavement Design and Maintenance
Section 5 : Surfacing and Surfacing Materials
Part 2 : HD 37/97 : Bituminous Surfacing Materials and Techniques
Chapter 8 is then the chapter on surface dressing.
This Highway Design Guide has been superseded by HD 37/99, but still includes the section on SURFACE DRESSING.
All Design Manuals can be downloaded in .pdf format by accessing the Highways Agency website.
DTP DESIGN MANUAL HD 37/99:SURFACE DRESSING-BINDERS-SMA-THIN WEARING COURSES
This DESIGN MANUAL FOR ROAD BRIDGES updates HD 37/97 and now includes information on a variety of surfacing materials and processes, including Chapter 8, an extremely useful guide on all aspects of SURFACE DRESSSING.
HD 37/99 now includes information on :-
laying bituminous surface courses,
binders and binder modifiers,
hot rolled asphalt,
porous asphalt,
thin wearing courses,
stone mastic asphalt,
high friction surfacing,
slurry surfacing
retexturing.
See also :- ***ROAD NOTE 39***
HIGH PRESSURE WATER RETEXTURING - TEXTURE - SURFACE DRESSING FATTING FAILURE
Modern engineering has progressed to a point where machines capable of spraying water at VERY HIGH pressure onto the road surface are available.
The water pressure will remove the matrix from around the larger aggregate thus restoring texture.
Although in principle this is an excellent process the surface you wish to treat has to be sufficiently sound/strong to withstand the force of the water.
The process is so aggressive as to easily destroy a surface consisting of a weak material.
The point has been raised that the process produces a large volume of water containing bitumen particles and road surface contaminants, in some areas there can be an environmental problem with disposal.
This process can successfully remove "fatting" of surface dressing,
and
fatting in bituminous surfacing material because of excess binder or poor material design.
HOT CHIP - SURFACE DRESSING
This is a specialized proprietary SURFACE DRESSING process, where as the name suggests the chippings are heated before spreading on the BINDER that has been laid on the road.
The chippings are heated to promote the bonding between the aggregate and the BINDER.
This is necessary with this process because the BINDER used is particularly stiff compared to normal SURFACE DRESSING binders.
To account for this increased stiffness the binder is not sprayed but is discharged upon the road from long tubes and is spread evenly upon the surface by rotating brushes.
The stiff BINDER and the use of hot chippings, plus adequate rolling achieves a very well established SURFACE DRESSING as soon as the binder has cooled to ambient temperature.
This type of SURFACE DRESSING is considerably more expensive than the traditional process.
See also:- ***SURFACE DRESSING***BINDER VISCOSITY***
IMMERSION TRAY TEST - SURFACE DRESSING CHIPPINGS - BINDER STRIPPING
This is a test to determine the wetting ability that different types of aggregate have for binder, this is particularly relevant to CUTBACK BITUMEN for SURFACE DRESSING.
The test is also used to determine the effectiveness of wetting agents.
Trays of binder of relevant thickness are prepared with the binder in its "as delivered state" and/or with differing concentrations of wetting agent added.
This is not a test applicable to BITUMEN EMULSION for obvious reasons!
The trays are placed under a covering of water, chippings are placed firmly into the binder through the water covering.
After a period of time chippings are removed from the binder and assessed for the degree of coating present.
It is not a test particularly liked by some CHIPPING suppliers, because it does show that some aggregates do have a greater natural affinity for BITUMEN than others.
See also:- ***CUTBACK BITUMEN***BITUMEN EMULSION***WETTING AGENTS***
INVERTED BREAKING - SURFACE DRESSING EMULSION - SURFACE DRESSING FAILURE
The phenomena of INVERTED BREAKING does not happen too often but when it does you ought to be fore-warned or you could be in trouble.
BREAKING normally occurs from the emulsion aggregate interface outwards to the surface of the emulsion,
With INVERTED BREAKING the BREAKING occurs on the surface of the emulsion, this means you have a thin layer of BITUMEN covering the emulsion preventing further water loss/evaporation.
I have not heard the cause sufficiently explained yet, but high humidity is thought to be a contributing factor.
Be aware, it does seem to affect polymer modified binders to a greater degree than standard K1-70 emulsion.
Whatever the cause it does mean you have chippings that do not firmly adhere to the road surface for some time and they can be STRIPPED quite easily causing serious and messy problems.
The remedy is VERY CAREFUL traffic control, very slow speeds, convoying if necessary.
Channeling the traffic over the complete road width by the use of cones, this is to keep puncturing the BITUMEN skin to allow BREAKING to continue.
Redress with smaller chippings/grit if necessary to keep any expose binder covered, do not allow exposed binder to be picked up on vehicles tyres to be carried forward and damage successful areas of dressing.
See also:-***BITUMEN EMULSION BREAKING***
K1-70 - BITUMEN EMULSION - SURFACE DRESSING BINDER - CATIONIC
K1-70 BITUMEN EMULSION is now the most widely used SURFACE DRESSING binder, and while it stays correctly formulated it is an excellent binder.
As its name (KI-70) suggests, it contains 70%, (in truth 67%), BITUMEN.
The "K" shows it is a cationic bitumen emulsion, as opposed to an anionic emulsion.
You should understand the BITUMEN used for the manufacture of the emulsion shall comply with BS 3690 and shall be selected from the range of bitumen grades 70PEN to 300PEN, although the penetration figure nearly always quoted is 200PEN as it is a good compromise VISCOSITY for most situations.
Do not confuse SPRAYING VISCOSITY of a surface dressing binder with its BASE VISCOSITY
Note : BS EN 12591 : 2000 : Bitumen and bituminous binders : Specification for paving grade bitumens ,
has superseded BS 3690, but reference to BS 3690 may still be present in some contract documents.
See also:-**BITUMEN EMULSION**BS 434**SPRAYING VISCOSITY**BASE VISCOSITY**
MEXE PENETROMETER - CBR - SURFACE DRESSING HARDNESS PROBE
This is a handheld device for assessing the CBR of soils on site.
Its precision may not be perfect but it is an excellent piece of kit for quickly assessing CBR's on site, and the number and speed with which results can be obtained offsets some inaccuracy
It was developed by the Military Engineering Experimental Establishment.
It is now produced by a civilian engineering firm and can be purchased from a number of laboratory equipment suppliers, and with the tip changed it can also be used for assessing road hardness for surface dressing.
See also:- ***ROAD HARDNESS PROBE***CBR***ROAD NOTE 39***TRRL REPORT SR 573***
MINI FRETTING TEST - SURFACE DRESSING
This was a test that was developed to determine the ability of a surface dressing binder to "hold" chippings, i.e. not "strip" when subject to a slight scrubbing action imposed by a small rubber roller revolving over a prepared sample of chippings and binder.
This test is currently little, if ever, used
The samples are prepared in exactly the same manner, i.e. same binder thickness, chippings, temperature, and loading of roller, etc..
With everything except the actual binder being the same, chipping loss will be attributable to binder performance, that is the theory, I do not believe it is, or was ever, an "approved" test.
The test, if it proves successful in reflecting actual on site performance, will be useful in comparing the performance of binders, especially polymer modified binders.
There are doubts about the REPRODUCIBILITY of this test, and it is losing favour to the VIALIT TEST.
See also:- ***MODIFIED BINDERS***SURFACE DRESSING STRIPPING***CSS ENG/3-94***VIALIT TEST***
MODIFIED BINDERS - SURFACE DRESSING
Although the bulk of these BINDERS are excellent products they must be used correctly just like any other SURFACE DRESSING binder.
You cannot use a lesser standard of workmanship thinking the improved binder will make up for that lesser standard.
In some cases a higher standard of care and awareness with this product is necessary because MODIFIED BINDERS are more prone to INVERTED BREAKING, which is a serious problem if you do not know how to deal with it.
It is unfortunate that it is being suggested that MODIFIED BINDERS are necessary for all SURFACE DRESSING nowadays.
THIS IS NOT SO!
Please read DTP ADVICE NOTE HA 33/86.
Any of the standard BINDERS that are of GOOD QUALITY are perfectly adequate for the bulk of SURFACE DRESSING.
See also:-***DTP ADVICE NOTE HA 33/86***CSS ENG/3-94***INVERTED BREAKING***K1-70***CUTBACK BITUMEN***BITUMEN EMULSION***MINI FRETTING TEST***VIALIT TEST***
RATES OF SPREAD OF SURFACE DRESSING CHIPPINGS - SANDWICH DRESSINGS
(Sandwich dressings will only be used as a "remedial" dressing on highly fatted surfaces.)
The following figures will be a good >>>GUIDE<<< to estimating the quantities of SURFACE DRESSING CHIPPINGS you require for SANDWICH DRESSINGS :-
....................CHIPPING SIZE ............Kg/Sq.metre ..........Sq.metres/Tonne
1st. LAYER .............20mm. ...................16 ......................62.5
1st. LAYER .............14mm. ...................13 ......................85
1st. LAYER .............10mm. ...................10 .....................100
2nd. LAYER .............10mm. ...................11 ......................90
2nd. LAYER ..............6mm. ....................8 .....................125
2nd. LAYER ..............3mm. ....................6 .....................150
See also:- ***AGGREGATE SIZE***BS 63***ROAD NOTE 39***RSDA PUBLICATIONS***RATES OF SPREAD OF SURFACE DRESSING CHIPPINGS-SINGLE-RACKED IN***
NOTE : If you dispute these figures do not email me, go out in
your depot yard, mark out a square metre, weigh out the guide amount
of chippings from your "source", and spread them by hand
over your square metre.Have you got too many or too few chippings, adjust your spread rate accordingly, allowing for some initial over-chipping to cover all binder.
It really is that simple if you are prepared to get you hands dirty, rather than sit in your office reading bits of paper, or websites, that tell you what your rate of spread should be, but this is how these figures were determined with the sources of aggregate that we had available.
RATES OF SPREAD OF SURFACE DRESSING CHIPPINGS - SINGLE - RACKED IN
The following figures will be a good >>>GUIDE<<< to estimating the quantities of SURFACE DRESSING CHIPPINGS you require for SINGLE DRESSINGS and RACKED IN DRESSINGS :-
CHIPPING SIZE .................Kg/Sq.metre ..............Sq.metres/Tonne
6mm. ............................8 ...........................125
10mm. ..........................11 ............................90
14mm. ..........................15 ............................65
20mm. ..........................19 ............................50
Racked in 10/6mm. ..............8 and 3 .......................125 and 335
Racked in 14/6mm. .............15 and 4 ........................65 and 250
See also:- ***BS 63***ROAD NOTE 39***RSDA PUBLICATIONS***
NOTE : If you dispute these figures do not email me, go out in
your depot yard, mark out a square metre, weigh out the guide amount
of chippings from your "source", and spread them by hand
over your square metre.Have you got too many or too few chippings, adjust your spread rate accordingly, allowing for some initial over-chipping to cover all binder.
It really is that simple if you are prepared to get you hands dirty, rather than sit in your office reading bits of paper, or websites, that tell you what your rate of spread should be, but this is how these figures were determined with the sources of aggregate that we had available.
ROAD HARDNESS PROBE - SURFACE DRESSING DESIGN
This is a standard instrument for determining the hardness of a road surface for SURFACE DRESSING purposes.
The hardness of a road being the most important factor in choosing the correct size of chipping.
There are two types of probe :-
One produced by Tar Industry Services, Chesterfield.
The other being the MEXE PENETOMETER with the tip used for determining CBR values changed for a tip capable of recording road hardness.
The more commonly used type is the MEXE PENETROMETER, mainly because of its dual use capabilities, i.e. assessing CBR values.
Details on the use of this instrument as a HARDNESS PROBE are included in :-
ROAD NOTE 39
and
TRRL Report SR 573.
See also:- ***MEXE PENETROMETER***ROAD NOTE 39***TRRL REPORT SR 573***
ROAD NOTE 39 - SURFACE DRESSING
This booklet is produced by the T.R.L. and is a most comprehensive guide to SURFACE DRESSING, and ALL staff involved with SURFACE DRESSING should have a copy, or at the very least, access to a copy.
ROAD NOTE 39 specifically includes tables for rates of spread of binder and appropriate chipping size for particular categories of road hardness and amount of traffic.
Guides on how to carry out SURFACE DRESSING design and supervision are also set out.
The FIFTH EDITION, is current, and includes PSV and skid resistance recommendations.
It is not too different from the previous edition, but has some binder increases, and does now include tables that were referred to in other technical documents.
It is also less user friendly. (In my opinion).
NOTE : The SIXTH EDITION of Road Note 39 became available in early 2008, it is unlikely that this document will apply to 2008 contracts.
I am led to believe that it does contain relevant up to date information that may affect the the nature of new contracting "arrangements", but with fundamental procedures, with a few minor exceptions, remaining much the same.
RSDA - ROAD SURFACE DRESSING ASSOCIATION
The ROAD SURFACE DRESSING ASSOCIATION represents the contractor / supplier side of the surface dressing industry.
It does produce an excellent "Code of Practice for Surface Dressing" and other guides, but these do contain a bias favouring the contractor, which is QUITE understandable.
Providing supervising staff are aware of this it does not detract from the bulk of good information, advice and guidance contained in these publications, and they are recommended reading.
The RSDA also organises courses for the training of supervisory staff involved with surface dressing.
See also:- ***ROAD NOTE 39***TRRL REPORT 627***RSDA PUBLICATIONS***
RSDA PUBLICATIONS - SURFACE DRESSING
This is a list of booklets and guide-notes issued by the ROAD SURFACE DRESSING ASSOCIATION, they are to be recommended, they are concise informative publications containing a lot of useful information, just be a little careful in reading some of them, remember they are produced by a body representing the contractor / surface dressing industry not the client / purchaser.
But they are still provide excellent information, they include the following :-
Guidance Note on Surface Dressing Aggregates
Code of Practice for Surface Dressing
Advice Note on Surface Dressing Binders
Guidance Note on Racked-in Surface Dressing
Operators' Guide to the Safe Use of Surface Dressing Sprayers
Preparing Roads for Surface Dressing
See:-***RSDA***
SECTOR SCHEME DOCUMENT NO.13 - SECTOR SCHEME DOCUMENT FOR THE SUPPLY AND APPLICATION OF SURFACE DRESSING TO ROAD SURFACES : FIRST EDITION JULY 1998
Published by the Sector Scheme Advisory Committee for the Quality Assurance of Surface Dressing, including :-
BM TRADA, BSI QSE, the Highways Agency and CSS (formerly the County Surveyors Society), Lloyds Register Quality Assurance Ltd., and the Road Surface Dressing Association (RSDA).
SPRAYING VISCOSITY - SURFACE DRESSING BINDER
SPRAYING VISCOSITY refers to the viscosity of the binder as it is formulated for the purpose of spraying from a binder sprayer/distributor.
The SPRAYING VISCOSITY is not related to the BASE VISCOSITY of the BINDER used in the formulation.
It is necessary that the SPRAYING VISCOSITY of surface dressing binders be substantially less viscous than the BASE VISCOSITY to allow it to be possible for the BINDER to be sprayed.
It is widely believed that a 200PEN binder is the usual BASE BINDER for SURFACE DRESSING.
Without "cutting back" or emulsifying this BINDER to make it less viscous it would not be possible to spray this material at practical and safe temperatures.
The establishment of the BASE BINDER viscosity on the road surface will not occur until the dispersal of all volatile oils or water used in the production of the BINDER for spraying, (this can take months in some cases, with regard to the volatile component, according to weather conditions).
See also:-***BASE VISCOSITY***KI-70***CUTBACK BITUMEN**
SURFACE DRESSING
SURFACE DRESSING is a low cost and effective way of sealing the surface of a road pavement against the ingress of water, and provide it with a suitable surface texture.
The road pavement should be sound, as a surface dressing will not impart any new strength, but maintain existing strength.
Surface dressing is comprehensively but not completely covered in ROAD NOTE 39, and everybody involved with SURFACE DRESSING should have a copy of this document.
TRRL REPORT 627 is an excellent guide to SURFACE DRESSING covering almost all aspects.
The SURFACE DRESSING process is basically the spraying of a thin film, (e.g.1.5mm.), of bituminous binder, (emulsion or cutback), on the road surface followed immediately by an application, at a suitable rate, of correct size and type chippings.
Use the "Find" and "Query" facilities of the database with the "key word" SURFACE DRESSING, plus "wild cards" (the star sign *) at each end to create a table/list of items about surface dressing and study each to find at what you need to know.
SURFACE DRESSING BINDER RATES OF SPREAD
These rates are laid down in tables in ROAD NOTE 39,
prescribed rates of spread will vary according to type of binder, hardness of the surface, traffic category, etc.
The actual rates of sprayed binder laid on the road will be depend upon such items as:-
(1) Forward speed of spraying tanker
(2) Viscosity of binder
(3) Temperature of binder, (temperature alters the spraying viscosity)
(4) Pressure in spraying tanker
All these items need to be continually checked.
BUT a check on laid binder rate of spread can quickly be performed using the BINDER TRAY TEST, it is quick and simple and sufficiently accurate to pick up any serious problems.
But if you want a figure just because you have no idea at all, variations on 1.5 litres per square metre of K1-70 bitumen emulsion is a reasonable figure to have in your head, and remember K1-70 emulsion is only 70% bitumen, the rest is water.
And 1.5 litres per square metre will give a depth of emulsion of 1.5mm. of emulsion, not bitumen.
See :-***BINDER TRAY TEST***
SURFACE DRESSING BINDER STRIPPING
This refers to the STRIPPING of binder from the chipping where the chipping contacts the binder.
A complete bond between chipping and binder is required as soon as possible to prevent chipping loss, the chipping is not secure until this bond is fully established.
If this bond is not achieved, or is initially achieved and then lost, the binder is said to have STRIPPED.
Without going into detail it is a fact that most aggregate has a greater affinity to have its surface covered with water than bitumen, this is simply a fact of chemistry.
SOME aggregates are more prone to stripping than others, and it is this affinity for water that causes the problem.
This is why weather is so critical with surface dressing.
If a fresh dressing receives heavy rain before the aggregate bitumen bond is established the failure can be major.
A quick tip, if this does happen to you completely cover the whole area with extra chippings, it is most important to keep a barrier between traffic wheels and the stripped binder, worry about why it happened later
Dusty chippings are a major cause of stripping, even after what appears a successful dressing, water will find its way around the chipping via the dust coating, the stripping will be delayed but it will occur.
CUTBACK BITUMENS are more prone to STRIPPING than EMULSIONS in surface dressing.
WETTING AGENTS can be added to CUTBACK BITUMEN to improve wetting / bonding, and this will considerably reduce the problem.
OF COURSE IF THE CHIPPINGS ARE FAIRLY DRY AND DUST FREE AND THERE ISN'T ANY RAIN ABOUT FOR A WHILE AFTER DRESSING YOU SHOULD NOT HAVE A PROBLEM.
Chippings strip for a variety of reasons other than BINDER STRIPPING.
See also:- ***IMMERSION TRAY TEST***WETTING AGENTS***
SURFACE DRESSING BINDERS
See :- ***BITUMEN EMULSION***CUTBACK BITUMEN***BS 434***BS 3690***K1-70*** ***MODIFIED BINDERS***
SURFACE DRESSING CHIPPINGS
SURFACE DRESSING CHIPPINGS presently used in this country are all "single sized"
i.e. the chippings are all meant to be a similar size so that when spread the dressing will achieve maximum texture, if spread on the correct hardness of road surface.
The size of chipping will be chosen according to the hardness of the road surface and the type and level of traffic.
See tables in ROAD NOTE 39.
The GRADING of the chippings will conform to BS 63:PART 2, (now PD 6682-2) and the authority contract document.
Amongst other criteria you will specify a minimum NOMINAL SIZE, (usually 60% or65%), it is this particular part of the specification which ensures the "single size" of the chipping.
A maximum dust content is specified, (you need clean chippings, no layer of dust between chipping and binder).
It is also necessary to have chippings with the correct PSV, the required PSV will depend upon the particular site.
See also:-**POLISHED STONE VALUE**DTP STANDARD HD 28/94****SKID RESISTANCE*** ***SURFACE DRESSING CHIPPING DUST CONTENTS***
SURFACE DRESSING CHIPPINGS - DUST CONTENT
The critical amount of dust (passing 75 or 63 micron) on surface dressing chippings is dependent on the SPECIFIC SURFACE of the chippings,
i.e. a sample quantity (weight) of 6mm. chippings will have a far greater surface area than the same weight of 14mm chippings.
Because dust contents are percentages by weight each sample may have the same amount of dust, BUT there will be less surface on a given weight of 14mm chippings for the dust to be "spread" on, compared to the same weight of 6mm chippings.
Therefore the 14mm chippings will be far more "dirty", so we have tighter / lower dust content specifications for larger chippings
Suggested dust contents for different size chippings are :-
14mm chippings = 0.5%
10mm chippings = 0.8%
6mm chippings = 1.0%
Low dust content of chippings is VERY important because layers of dust between chipping and BINDER layer will prevent adhesion and allow easier ingress of moisture prior to good embedment.
See also:- ***SURFACE DRESSING CHIPPINGS***BS 63:PART 2***
SURFACE DRESSING EMULSIONS
K1-70 is the most widely used surface dressing emulsion used and has its own page in this database.
There are an increasing number of proprietary surface dressing emulsions on the market, some of them quite well known, others less well known.
These binders usually contain a polymer additive and claim to improve the performance of the emulsion, this increase in cost must be balanced against perceived benefits.
I would suggest anybody thinking about using modified emulsions read DTP ADVICE NOTE HA 33/86, now superseded by HD 31/94, but still excellent reading,
also CSS ENG/3-94 : Polymer Modified Binders for Surface Dressing.
It is generally considered improved emulsions are only necessary on high stressed sites.
See also:- ***K1-70***BS 434***BITUMEN EMULSION***DTP ADVICE NOTE HA 33/86***INVERTED BREAKING***CSS ENG/3-94***
SURFACE DRESSING FRETTING
This term means the loss of chippings, applied as part of the surface dressing process, from the layer of binder applied to the road surface.
See also:- ***SURFACE DRESSING STRIPPING***SURFACE DRESSING BINDER STRIPPING***
SURFACE DRESSING SEASON - PROLONGING - IMPLICATIONS
If it is necessary to have an extended season in order to complete a large surface dressing programme,
I would recommend that you start earlier rather than finish late.
I would NOT recommend anything other than a 6mm. dressing in September, if you MUST do any dressing at all that late, and even this 6mm. work must be on low stress sites.
This does NOT mean changing a chipping size that by design should be a 10mm. or a 14mm. to a 6mm. in order to prevent winter failure, by doing that you are only storing up problems for yourself in the following season, i.e. the 6mm.will push in the soft surface where a 10mm. or 14mm. was needed, and you will have failure by fatting up, especially if you are foolish enough to increase the binder content above that indicated in Road Note39 in order to try and prevent winter stripping.
It means programming your 6mm. sites for late in the season.
Dressings applied early have the warmth of the summer to embed.
Late dressings, (late August and early September) give very little time for embedment of larger chippings.
It is wise, if possible, to complete all 14mm. work early in the season , I would suggest by the end of July, and that includes sites where you will be using polymer modified binders.
See also:- ***ROAD NOTE 39***TRRL REPORT 627***
SURFACE DRESSING SPECIFICATION REFERENCES
These references are discussed in this guide:-
ROAD NOTE 39:- Surface Dressing "bible",binder/chipping rates of spread etc., the 1996 edition is current, and it has been amended.
TRRL REPORT 627:- An excellent guide to all aspects of SURFACE DRESSING
BS 63:PART 2:- Specification for single sized aggregate for surface dressing
BS 434:PART 1:- Specification for bitumen road emulsions
BS 3690:PART 1:- Specification for bitumens for roads and other paved areas
BS 1707:- Specification for hot binder distributors for road surface dressing
D.Tp. HD 28/94 - Skidding Resistance - Specification requirements for aggregate properties and texture depth for bituminous surfacings to new roads, supersedes HD 21/92.
D.Tp. Highways Advice Note H.A.33/86:Modified binders for surface dressing, provides guidance on the use of modified surface dressing binders, superseded by HD 31/94, but often still referred to.
D.Tp. HD 37/97 - Bituminous Surface Materials and Techniques - Chapter 8:Surface Dressing
I
have not updated the above list of technical references, as the above
documents are still "popular" although some may have been superseded,
and they do contain good, understandable, information.I regard them as still worth reading if you are able to obtain copies, it is my belief that you will better understand the "new" documents after having read the documents that they superseded.
But for contractual purposes they are likely to have been superseded, and you do need to be aware of this, and to update in your technical library as appropriate.
Appropriate reference to the superseding documents is contained in other relevant items on this page.
See also :- ***RSDA PUBLICATIONS***
SURFACE DRESSING STRIPPING
This term means the loss of aggregate, i.e. SURFACE DRESSING CHIPPINGS, from the laid BINDER, this can be for a number of reasons and the term "STRIPPING" is not specific to any particular cause in this broad context.
Possible reasons are:-
1) Too low RATE OF SPREAD OF BINDER
2) Wrong HARDNESS assessment of surface
3) Too large a chipping chosen for the road surface
4) Dressing too late in the year not allowing embeddment of chippings
5) Dusty chippings preventing bonding
6) Rain before the chippings have been thoroughly wetted by the binder,
N.B. most aggregate has a greater affinity for water than bitumen.
Until the aggregate is well "wetted" with bitumen, i.e. there is a definite bond between aggregate and chipping, water will be able to displace bitumen from the aggregate surface.
See also:-***STRIPPING OF BINDER***IMMERSION TRAY TEST***
TRL Project Report 12 : The testing and performance of surface dressing binders for heavily trafficked roads
A large part of this report is details on road trials incorporating differing binders and processes, and the results obtained.
Use of modified binders is referred to.
See also:- ***MODIFIED BINDERS***CSS ENG/3-94***
TRL Report 261 : The long term performance of a surface dressing trial on A413, Amersham
Various test lengths of type and size of chipping were laid for study after trafficking, the various results are recorded and possible conclusions drawn.
TRRL REPORT SR 573 - SURFACE DRESSING HARDNESS
This report sets out the procedures for assessing the hardness of road surfaces in respect to surface dressing.
Road hardness and traffic flow / type govern the size of chipping chosen for a particular site.
See also:- ***ROAD HARDNESS PROBE***ROAD NOTE 39***
TRRL Supplementary Report 627 : A guide to road surface dressing practice
This is an excellent, very comprehensive, report on SURFACE DRESSING, it may be a few years old now but good information is never out of date, and it is recommended reading.
TRRL Report SR 798 : High performance surface dressing : No. 3, Properties of thermosetting binders related to road performance
The report is relevant to providing small areas of high skid resistance, largely using extremely hard calcined bauxite chippings as the aggregate.
VIALIT TEST - SURFACE DRESSING BINDER TESTING - COHESIVITY - ADHESIVITY
There are two VIALIT TESTS, they are physical tests for determining the adhesivity and cohesivity of surface dressing binders, the tests actually take two distinct forms.
One form where a standard heavy ball is dropped on to an inverted tray to which is stuck a number of small steel balls (or chippings), the number of balls (or chippings) retained indicating the properties of the binder under test.
The second form of test is where a steel cube is stuck to a firm base with the binder under investigation and impacted by a pendulum capable of applying a range of standard force, the ability of the binder to resist removal of the steel cube indicates a binder with good characteristics.
These physical tests are claimed to be a way assessing the quality of the various types of binder, especially polymer modified binders, and the same binder at different temperatures.
There is a draft standard for the VIALIT TEST, i.e. Draft CEN StandardTC19/SC1
Details of the VIALIT TEST are now included in the 900 Series of Volume One of the Specification for Highway Works.
WETTING AGENTS - SURFACE DRESSING - CUTBACK BITUMEN
These are additives / chemicals that are added to CUTBACK BITUMEN to increase its ability to "wet" aggregate, i.e. the binder will adhere to the aggregate surface more quickly.
This is particularly important if rain is likely.
It is during periods of unsettled weather that WETTING AGENTS are used so that SURFACE DRESSING can continue with the reduced risk of STRIPPING if rain does occur.
These WETTING AGENTS are not cheap so a considerable amount of judgement needs to be exercised in their use.
N.B. WETTING AGENTS are not used in BITUMEN EMULSION.
See:- ***SURFACE DRESSING BINDER STRIPPING***IMMERSION TRAY TEST***
WHY DID IT FAIL ? - SURFACE DRESSING FAILURE
SURFACE DRESSING fails for many reasons and it MUST be said most of the causes of failure can be controlled.
For those of you with little experience of SURFACE DRESSING I would recommend you first read and digest Road Note 39, and TRRL Report 627.
If you do not have immediate access to them read the items on this web site related to SURFACE DRESSING..
BUT I will list some of the many factors that contribute to failure for you to consider, BUT in some cases (and ONLY some) the failure can be obvious:-
[1] Road hardness assessed wrongly.
[2] Wrong size chipping used.
[3] Wrong rate of spread of BINDER chosen.
[4] Different rate of spread of BINDER sprayed to that chosen, e.g.,
a) Speedometer of sprayer inaccurate
b) Incorrect "rate of spread speed chart" for a particular sprayer
c) Tank pressure incorrect
d) BINDER VISCOSITY not that specified.
[5] Wrong BINDER VISCOSITY specified for ambient temperature.
[6] Badly formulated BINDER e.g. unsuitable BASE BINDER.
[7] Poor traffic control.
[8] Site not suitable for surface dressing, e.g. areas of "screwing" traffic.
[9] Ambient temperature too cold.
[10] Dirty/dusty chippings. ETC. ETC.