In terim guide lines for primes and stone precoating fluids

In terim guide lines for primes and stone precoating fluids Manual 6 November 006 Pub lished by Sabita Postnet Suite 56 Pri vate bag X Howard Place 7450 ISBN 8749689

Manu als pub lished by Sabita Man ual Man ual Man ual 3* Man ual 4* Man ual 5 Man ual 6* Man ual 7 Man ual 8 Man ual 9 Man ual 0 Man ual Man ual Man ual 3 Man ual 4 Manual 5* Man ual 6 Man ual 7 Man ual 8 Man ual 9 Man ual 0 Man ual Man ual Man ual 3 Man ual 4 Man ual 5 Man ual 6 Construction of bitumen rubber seals Bituminous products for road construction Test meth ods for bi tu men rubber Specifications for rubber in binders Man u fac ture and con struc tion of hot mix as phalt Interim specifications for bitumen rubber SuperSurf: Eco nomic war rants for sur fac ing un paved roads Safe and responsible handling of bituminous products Bituminous surfacings for temporary deviations Appropriate standards for bituminous surfacings Labour enhanced construction for bituminous surfacings Methods and pro ce dures La bour en hanced con struc tion for bituminous surfacings LAMBS The de sign and use of large ag gre gate mixes for bases GEMS The de sign and use of gran u lar emul sion mixes Technical guidelines for seals using homogenous modified binders REACT Economic analysis of shortterm rehabilitation actions The de sign and use of po rous as phalt mixes Ap pro pri ate stan dards for the use of sand as phalt Technical guidelines for bitumenrubber asphalt Sealing of ac tive cracks in road pave ments ETB: The de sign and use of emul sion treated bases Hot Mix Pav ing in Ad verse Weather Bitumen Hauliers Code: Guidelines for loading bitumen at refineries User guide for the de sign of hot mix as phalt Qual ity man age ment in the han dling and trans port of bi tu mi nous binders In terim guide lines for primes and stone precoating flu ids * These man u als have been with drawn and their con tents have been in cor po rated in a man ual en ti tled: The use of mod i fied bind ers in road con struc tion pub lished as Tech ni cal Guide line by the As phalt Acad emy TRIP HMA HSE CEP Training Guides Bituminous pavement repairs:technical Recommendations in Prac tice Hot mix As phalt Training Se ries Health, Safety and En vi ron men tal Guide lines for bi tu men and coal tar prod ucts Councillor Empowerment Programme 3

Sabita Video Se ries Testing of bituminous products Bi tu men AV Pen e tra tion test / Softening point (ring and ball) AV Spot test / Rolling thin film oven test AV3 Brookfield vis cos ity / Duc til ity Bitumen Emulsion AV4 Saybold furol vis cos ity / Wa ter con tent of emul sions AV5 Sed i men ta tion value of emul sions / Res i due on siev ing AV6 Co ag u la tion value with chip pings / Co ag u la tion value with Portland cement AV7 Binder con tent of slurry / Par ti cle charge test Hot Mix As phalt AV8 Op ti mum binder con tent for as phalt AV9 Mar shall test AV0 Binder con tent / Mois ture con tent AV Static creep test / Im mer sion in dex AV Rice s den sity and binder ab sorp tion/bulk rel a tive den sity and voids Bitumen Rubber AV3 Ball pen e tra tion and re sil ience test / Dy namic vis cos ity AV4 Com pres sion re cov ery / Flow test AV5 Bulk den sity of crumb rub ber / Grading and loose fi bre test of crumb rub ber Black top Roads AV Blacktop roads for re con struc tion and development AV Black top sur fac ing and re pair (with In struc tor Training Man ual) AV3 Pave ment sur fac ing and re pair for black top roads Hot Mix As phalt AV5 Manufacture AV6 Paving AV7 Com pac tion Health, Safety and En vi ron men tal Conservation AV8 BitSafe The safe han dling of bi tu men (DVD) 4

DIS CLAIMER Con sid er able ef fort has been made to en sure the ac cu racy and re li abil ity of the in for ma tion con tained in this pub li ca tion. How ever, nei ther Sabita nor SAT nor a any of their mem bers can ac cept any li a bil ity what so ever for any loss, dam age or in jury re sult ing from the use of this in for ma tion. The con tents of this pub li ca tion do not nec es sar ily rep re sent the views of all mem bers of Sabita and SAT. 5

CONTENTS Pref ace 7 Introduction 9 Sec tion A: Prim ing of bases 0. Def i ni tion of a prime 0. Func tions of a prime 0 3. Re quire ments of a prime 4. When do you need a prime? Types of prime 3. Stan dard prod ucts 3. Pro pri etary prod ucts 3 Se lec tion cri te ria 4 Construction considerations 5. Ap pli ca tion rates 5. Prep a ra tion of the base 6 3. Spray ing of the prime 6 4. Dry ing of the prime 6 5. Prim ing bases that con tain sol u ble salts 7 Sec tion B: Stone precoating flu ids 8. Def i ni tion of a stone precoating fluid 8. Func tions of a stone precoating fluid 8 3. Re quire ments of a stone precoating fluid 8 4. Fac tors dic tat ing the need to precoat 9 Construction considerations 3. Pro ce dures for precoating 3. Ap pli ca tion rates 3 3. Al ter na tive con struc tion tech niques to the use of precoating flu ids 3 Ref er ences 5 6

PREFACE This in terim guide line has its foun da tion in Sabita s pub licly stated un der tak ing to im ple ment global stan dards of worker safety, health and en vi ron men tal conservation into southern Africa s road construction and bituminous products industry. In ter na tional best prac tice in re cent years had es tab lished that the use of coal tar products in road construction introduces inherent carcinogenic hazards, while at the same time pos ing a se ri ous con tam i na tion threat to the en vi ron ment in clud ing ground wa ter and its aquatic life. Encouraging the discontinuation of coal tar usage in the bituminous products in dus try has be come a cor ner stone of Sabita s Health, Safety and Environmental Conservation (HSE) policy, and is part of a broader undertaking, driven by the or gani sa tion s Cen tre for Oc cu pa tional Safety, Health and Environmental Conservation (COSHEC). Integral to this initiative are several cur rent ac tiv ity ar eas in clud ing the Bi tu men Safety course (BitSafe), the Load Accreditation Programme (LAP), an Incident Reporting framework, Sabita Safety File and the safe disposal of bitumen waste. By mid006 Sabita s aware ness programme aimed at dis cour ag ing the use of coal tar prod ucts had yielded sig nif i cant re turns, and the South Af ri can Na tional Roads Agency Lim ited (SANRAL), the West ern Cape Pro vin cial Ad min is tra tion, the Gauteng De part ment of Pub lic Trans port, Roads and Works, and the Roads Agency Limpopo have now banned the use of these prod ucts. Re gret ta bly, very few of the 48 lo cal gov ern ment au thor i ties have fol lowed suit, de spite am ple proof that al ter na tive, bi tu menbased prod ucts, are readily avail able al beit at a mar ginal in crease in cost. It is hoped that the po si tion pa per out lin ing the car ci no genic dan gers and en vi ron men tal haz ards in her ent in the use of coal tar prod ucts, pre pared by Sabita s for mer ex ec u tive di rec tor Piet Myburgh and for warded to COTO and IMIESA for broader ex po sure, will com ple ment this guide line and en trench the global move to wards safer, en vi ron men tally friendly alternatives to coal tar products. 7

This doc u ment fo cuses only on prim ing gran u lar bases and precoating sur fac ing stone. It is in tended to serve as an in terim guide line to cap ture best prac tice un til such time as doc u ments such as the out dated TRH : Prime coats and bituminous curing membranes, which was pub lished in 986, are up dated. Precoating of road stone is pri mar ily done to im prove the ad he sion be tween the stone and binder. In the ab sence of a na tional spec i fi ca tion, it is pro posed that a prod uct spec i fi ca tion for bi tu menbased precoating fluid be pro vided to re place its coal tar equiv a lent. Us ers of bi tu men based primes and precoating flu ids need to be aware that these prod ucts con tain pe tro leum cut ters and ev ery ef fort must be taken to en sure that all work ers are aware of the haz ards and risks as so ci ated with these prod ucts. To this end all sup pli ers are re quired by law to pro vide Ma te rial Safety Data Sheets which inter alia state the haz ards and dan gers as so ci ated with their prod ucts. Trevor Distin Chief Ex ec u tive Of fi cer Sabita Acknowledgments Sabita gratefully ac knowl edges the con tri bu tions made by the fol low ing peo ple in the com pi la tion of this document: Dennis Rossmann SANRAL Kobus Louw Co las South Af rica Johan Mul ler Tosas Trevor Distin Sabita 8

Introduction Al though the use of coal tar for prim ing gran u lar bases and precoating sur fac ing ag gre gates has been com mon prac tice in South Af rica, global best prac tice now dic tates the dis con tinu a tion of these bind ers for rea sons of pro tect ing worker health and environmental conservation. The pur pose of this guide line is to as sist road au thor i ties with the se lec tion of proven al ter na tive prod ucts and pro cesses that have been used suc cess fully. These rec om men da tions are based on a se ries of work shops hosted by the So ci ety of As phalt Tech nol ogy (SAT), dur ing which the use of al ter na tive prod ucts and pro cesses was presented and discussed. While coal tar has been used in a va ri ety of road con struc tion ap pli ca tions over many de cades, this doc u ment fo cuses only on prim ing gran u lar bases and precoating surfacing stone. 9

SEC TION A: PRIM ING OF BASES. Def i ni tion of a prime A coat of suit able bi tu mi nous binder ap plied to a nonbi tu mi nous gran u lar pave ment layer as a pre lim i nary treat ment prior to the ap pli ca tion of a bituminous base or surfacing. Note: A tack coat on the other hand is ap plied to a primed sur face or bi tu mi nous sur face to pro mote ad he sion be tween the ex ist ing and a new as phalt pave ment layer. Espe cially dur ing the com pac tion of the lat ter, bitumen emul sions are al most in vari ably used for this pur pose and are nor mally ap plied to a primed sur face im me di ately be fore plac ing a hot mix as phalt layer.. Func tions of a prime The main func tion of a prime is to pen e trate the layer to which it is ap plied while leav ing a small re sid ual amount of binder on the sur face to: Note: As sist in pro mot ing ad he sion be tween the base and the newly applied bituminous surfacing or layer; In hibit the in gress of wa ter from rain into the base while not ham per ing the mi gra tion of wa ter in the vapour phase out of the base; Limit the ab sorp tion of binder from the next spray ap pli ca tion into the base; Bind the finer par ti cles on the up per zone of the base to ac com mo date light con struc tion traf fic for a short pe riod un til the new sur fac ing can be placed. Primes are not suit able to be ap plied to cementitious sta bi lised ma te ri als as cur ing mem branes to pre vent the loss of mois ture and car bon ation from tak ing place in the layer. To this end nor mal bi tu men emul sions have been found to per form the best. 0

Fig ure : Nonpen e trat ing ef fect of an oilinwa ter bi tu men emul sion Fig ure : Pen e trat ing ef fect of an in verted bi tu men emul sion prime

3. Re quire ments of a prime Low viscosity cutback bitumens or inverted bitumen emulsions generally meet the re quire ments of a prime. Or di nary oilinwa ter type bi tu men emul sions such as Stablemix and spray grades are not suit able as primes as they do not pen e trate dense bases. The bi tu men drop lets co alesce on the sur face to form a skin af ter the wa ter has been absorbed or evaporated. Af ter a prime has been sprayed it pen e trates the base layer and starts to cure through the loss of volatiles by evap o ra tion and ab sorp tion. The prime should be for mu lated in such a way that once it is sprayed, it dries within a rea son able pe riod to al low for the con struc tion of the next layer to take place with out pickup by the tyres of con struc tion plant. The vis cos ity of the prime should not be re duced to im prove pen e tra tion through heat ing. In other words all primes should be able to pen e trate at ambient tem per a ture. 4. When do you not need to prime? Prim ing of a base is not re quired when: Spray ing MC 3000 cut back bi tu men on G bases ex hib it ing a dense ma trix of smooth stone sur faces; Sur fac ing a sur face en riched with emul sion or foam treated base; Spray ing a semiprim ing binder for the con struc tion of a graded seal such as an Otta seal. If the prime is omit ted the con struc tion of the seal should pro ceed with out de lay, and the first spray ap pli ca tion should be in creased by + 0.5 l/m² to al low for some ab sorp tion of the binder into the base.

Types of prime. Standard products: MC 30 and MC 70 cut back bi tu men grades com ply ing with SANS 308; Inverted bitumen emulsion complying with SANS 60. Prob lems have been re ported with MC 30 not pen e trat ing dense crushed stone bases and nat u ral gravel bases with a high clay con tent. The prime can take up to one week or lon ger to dry un der these con di tions. In or der to im prove the pen e tra tion of these primes into dense bases, the vis cos ity of MC 30 can be lowered by adding 0 5% additional illuminating paraffin, and the prime ap pli ca tion rate can also be low ered. The ad di tion of cut ter should take place in a con trolled en vi ron ment at the binder man u fac tur ers blend ing plant, both for safety rea sons and to en sure that a ho mog e nous mix is achieved. In the case of an in verted emul sion, the cut ter and/or wa ter con tent can be in creased. In the lat ter case the max i mum wa ter con tent limit of 0% of the total volume should not be exceeded.. Proprietary products: If primes are to be used that do not com ply with SANS spec i fi ca tions, the sup plier should provide spec i fi ca tions against which his prod uct can be tested for compliance. These specifications should meet the following SANS requirements for the distillation test: Min i mum res i due from dis til la tion of 50% of the to tal vol ume; and Penetration at 5 0 C of the res i due should be be tween 90 and 80 dmm. 3

Selection criteria The main fac tors that in flu ence the se lec tion of the type of prime to be used are the type and the ab sorp tive prop er ties of the base and the pre vail ing weather conditions. Ta ble : Se lec tion ma trix Type of base MC 30 MC 70 Inv. emul. Graded nat u ral gravel e.g. weath ered G+ Crushed stone e.g. unweathered G/G * Lime or ce ment sta bi lised Bituminous stabilised Calcrete Containing soluble salts Ab sorp tive prop er ties of base ma te rial High mois ture con tent Low mois ture con tent High de gree of densification Low de gree of densification High porosity Low porosity Plasticity index >7 Plastic Index <7 Open graded Cli ma tic con di tions High Humidity Wet Road temperature >5 0 C Road temperature <5 0 C Key: = pri mary rec om men da tion; = sec ond ary rec om men da tion; = not suitable * Lower vis cos ity by cut ting back with il lu mi nat ing par af fin. 4

Construction considerations. Application rates Ide ally, the se lected ap pli ca tion rate should be such that the sur face will ab sorb the ap plied prime and de posit a thin, quick drying film on the sur face. The ap pli ca tion rates will vary ac cord ing to the type of base and its ab sorp tive prop er ties, and these rates should also be ad justed to take into con sid er ation the net re sid ual binder of each product. (See Table ) As a rule of thumb the ap pli ca tion rates se lected should ren der a net re sid ual binder of 0.35 kg/m which equates to a spray rate of 0.7 l/m for MC 30, 0.6 l/m for MC 70 and 0.95 l/m for in verted bi tu men emul sions. The fol low ing ad just ments to the net re sid ual binder are rec om mended: If the base is coarse or open in crease the ap pli ca tion rate by 5%; If the base is fine and dense de crease the ap pli ca tion rate by 5%. How ever, to en sure that the cor rect ap pli ca tion rate is se lected, it is rec om mended that a paint test be done on the pre pared base. This is best achieved by mark ing out ar eas of one square metre and ap ply ing the can di date prime with a brush at dif fer ent ap pli ca tion rates to de ter mine the ideal application rate. Ta ble : Typ i cal prop er ties of primes for de ter min ing ap pli ca tion rates Prod uct Density @ 0 0 C (kg/l) Spray temperature ( 0 C) Density @ spray temperature (kg/l) Net residual binder con tent (%m/m) MC 30 0.93 55 0.9 55 MC 70 0.95 70 0.9 64 Inv. Emul. 0.9 60 0.90 4 5

. Prep a ra tion of the base Prim ing should be car ried out only af ter the base has dried out suf fi ciently to ob vi ate the en trap ment of ex cess mois ture, which may lead to an un de sir able build up of mois ture un der the newly placed sur fac ing and pos si bly lead to pre ma ture dis tress. The base should be broomed clean of all loose ma te rial un til the larger gravel and stone ag gre gates are ex posed. The sur face of the base should be moist ened by a light sprin kling of wa ter prior to prim ing to re duce the sur face ten sion and to avoid the for ma tion of fish eyes in the primed sur face. Care should be taken not to ap ply ex cess wa ter and thus sat u rate the layer as voids filled with water cannot be filled with prime. 3. Spray ing of the prime Spray ing of prime should not be done if the ex pected min i mum air tem per a ture for the en su ing seven days is be low 0 0 C, or when rain is im mi nent. Spray ing should only be done when the sur face tem per a ture of the base is 0 0 C and ris ing. The ac tual spray rate should not de vi ate by more than 0.06 l/m of the target rate. Care should be taken when heat ing the prime prior to ap pli ca tion as the spray tem per a ture could be above the flash point of the cut ter. In the case of both MC grades and in verted emul sions, il lu mi nat ing par af fin is used as the cut ter, and has a flash point of + 40 0 C. The heat ing of prime should only be car ried out as soon as is prac ti ca ble be fore spray ing so as to pre vent loss of the vol a tile frac tions. The rea son for heat ing the prime is to en sure that it flares prop erly when dis charged through the noz zles on the spray bar of the dis trib u tor. Cut back and in verted emul sion primes are pump able at am bi ent tem per a ture and thus do not need to be heated dur ing load ing, trans port, offloading and storage. 4. Dry ing of the prime For a given prime the dry ing time will de pend on the po ros ity of the base and the prrevailing weather con di tions. The prime should be al lowed to dry be fore open ing to traf fic or pro ceed ing with con struc tion of the next layer. Any pool ing of prime on the sur face should be blinded with crusher dust and removed. 6

5. Prim ing bases that con tain sol u ble salts The adhesion of bituminous materials to pavement layers containing soluble salts can be a prob lem. Ex pe ri ence has shown that the base should be primed im me di ately af ter com ple tion and be sur faced within 4 hours with hot bi tu men or mod i fied bi tu men. The base should not be damp ened be fore prim ing as this can cause the dis solved salts to mi grate to the sur face and recrys tal lise during curing of the prime. 7

SEC TION B: STONE PRECOATING FLU IDS The pro cess of precoating sur fac ing ag gre gates has be come com mon prac tice and is con sid ered a cost ef fec tive mea sure to mini mise the risk of poor ad he sion and the pos si bil ity of early chip loss and strip ping in seals. Precoating should not be re placed by add ing cut ter to the binder, nor should it be seen as a sub sti tute for proper work man ship or ac cept ing dirty aggregates.. Def i ni tion of a precoating fluid: A low viscosity bituminous based binder containing petroleum cutters and a chem i cal ad he sion agent which is used to precoat sur fac ing ag gre gates to im prove the ad he sion of the ag gre gate to the bituminous binder.. Func tions of a precoating fluid: The precoating fluid as sists in re duc ing the sur face ten sion be tween the cold sur fac ing ag gre gate and the freshly sprayed hot vis cous binder dur ing con struc tion of the seal, thereby aid ing the ini tial bond be tween the ag gre gate and the binder as the lat ter cools down. 3. Re quire ments of a precoating fluid: The precoating fluid should have a low enough vis cos ity to coat damp or dusty sur fac ing ag gre gates, and be able to dry in a rea son able pe riod to de posit a nontacky re sid ual film on the sur face of the ag gre gate. The fluid should not cause a de posit of binder to be left on the site that would be harm ful to the environment. Note: The use of bi tu men emul sion or die sel has been found in most cases to be un suit able for use as precoating flu ids. The ad di tion of at least 0,5% of a chem i cal ad he sion agent to the to tal mass of the precoating fluid is es sen tial to: en hance the ad he sion of ag gre gate to the binder in the pres ence of moisture; and im prove the ad he sion of ag gre gates that have a poor af fin ity for bi tu men for e.g. quartzitic or si li ceous ag gre gates. 8

In the ab sence of a na tional stan dard spec i fi ca tion the fol low ing rec om men da tion is made based on the suc cess ful use of pro pri etary bitumenbased precoating fluids. Table 3: Specification for a bituminousbased precoating fluid Prop erty Re quire ment Test method Den sity @ 5 0 C, kg/l 0.85 0.95 Saybolt Furol vis cos ity @ 50 0 C, SFs 0 30 ASTM D 44 Distillation to 360 0 C, v/v% To 90 0 C 5 0 C 60 0 C 36 0 C 0 5 0 55 45 75 70 95 ASTM D 40 Residue from distillation to 360 0 C, v/v% 45 60 ASTM D 40 Dynamic viscosity @ 5 0 C of res i due dis tilled to 360 0 C (cps) 300 500 ASTM D440 Stripping number Report Riedel & Weber. This test should be con ducted to as sess the ef fect of precoated ag gre gate ver sus unprecoated ag gre gate on the ad he sion to the pro ject binder. 4. Fac tors dictat ing the need to precoat The main fac tors in flu enc ing the need to precoat sur fac ing ag gre gates de pend on the type of ag gre gate, binder and seal to be used. The se lec tion of cer tain types of seals and the con com i tant use of bi tu men emul sions and clean washed ag gre gates can dis pense with the need to precoat ag gre gates. Ta ble 4 pro vides a guide line on when to precoat. 9

Fig ure 3: In flu ence of an ad he sion agent on precoated ag gre gate af ter the strip ping test Fig ure 4: Precoated ag gre gate with out ad he sion agent af ter the strip ping test 0

Ta ble 4: Cri te ria for precoating sur fac ing ag gre gates Key: = essential; = optional; = not re quired Seal type Rec om men da tion Single seal Multiple seal Cape seal Graded seal * ** ** *** Binder type Penetration Cutback Emul sion Hot poly mer Bitumen rubber Type of ag gre gates Hydrophilic Dust con tent >% Porous Quartzitic Granite * Not re quired if emul sion used as a tack spray. ** Not re quired if di luted emul sion used as a cover spray. *** Not re quired if the binder is cut back or an ad he sion agent is added to the binder. To a lesser ex tent the fol low ing con sid er ations may also in flu ence the need to precoat the sur fac ing stone:

. Black sur face The need to precoat is some times deemed de sir able in or der to cre ate a dark sur face in or der to con trast the line mark ings es pe cially when light col oured aggregates are used.. Low road and am bi ent tem per a tures When lower than nor mal work ing tem per a tures are ex pected to be en coun tered the need to precoat is rec om mended in or der to re duce the risk of strip ping in the early life of the seal as the precoating fluid will pro mote ad he sion be tween the binder and ag gre gate. The use of a precoating fluid is pre ferred to cut ting back the binder when cooler weather is ex pected as the lat ter can lead to bleed ing of the seal with the on set of warmer weather and under heavy traffic. 3. Traf fic If the de sign traf fic vol ume and/or ve hi cle speed is high then the risk of strip ping can be re duced by precoating as the precoating fluid will pro mote ad he sion be tween the binder and ag gre gate. The same ap plies to high stress ar eas where the ra dii of cur va ture are tight and the in ci dence of turn ing ac tions of vehicles is high.

Construction considerations. Pro ce dures for precoating Ag gre gates can ei ther be precoated on site us ing a front end loader prior to sur fac ing, or they can be coated in a drum plant which is usu ally sit u ated at a quarry. The stone to be precoated should be slightly damp but not wet. Once the precoating fluid is added at am bi ent tem per a ture, it should be thor oughly mixed to en sure a uni form coat ing. The stock pile may have to be pro tected from rain to pre vent washoff. The precoated ag gre gates should be al lowed to dry for at least four days be fore use. The precoated ag gre gates have an un lim ited stock pile life as long as they are pro tected from dust and rain.. Ap pli ca tion rates The quan tity of precoating fluid should be suf fi cient to coat each ag gre gate particle uniformly. Experience to date indicates that while the application rate for bi tu mi nous based precoating flu ids is gen er ally slightly higher than that used for coal tar based prod ucts, the quan tity will de pend mainly on both the clean li ness and po ros ity of the ag gre gates. Dusty ag gre gates will re quire a heavier ap pli ca tion than clean dry ag gre gates of the same type and size. Sim i larly the rate for po rous ag gre gates will be higher than for dense smooth aggregates. Ta ble 5: Typ i cal ap pli ca tion rates for bi tu men based precoating fluids Stone size (mm) 6.7 9.5 3. 9 Litre/m 3 3 8 7 6 0 5 The rec om mended method for de ter min ing the ap pli ca tion rate is to precoat small sam ples of the job ag gre gates with vary ing quan ti ties of precoating fluid, and then make a vi sual as sess ment as to the quan tity which ren ders the ideal coating. 3. Al ter na tive con struc tion tech niques to the use of precoating fluids The need to precoat the sur fac ing ag gre gate can be dis pensed with by split ting the ap pli ca tion of the binder spray in the con struc tion of the seal. The tack and pen e tra tion sprays can be re duced to al low for the use of a di luted bi tu men emul sion as a cover spray over the com pleted stone seal. This is ap pli ca ble to 3

both mul ti ple and Cape seals where the lower layer of ag gre gate will be locked in by the sec ond ap pli ca tion of smaller ag gre gates or slurry respectively. In the case of graded seals or hot poly mer mod i fied bind ers, an ad he sion agent can be preblended into the binder prior to spray ing to im prove ad he sion. 4

References. Draft TRH 986: Prime coats and bi tu mi nous cur ing mem branes. SANS 308 973: Standard Specification for cutback bitumen 3. SANS 60 979: Standard Specification for invert bitumen emulsion 4. COLTO 998: Stan dard spec i fi ca tions for road and bridge works for state road authorities 5. www.co las.co.za Typical binder contents, spray application temperatures and Prod uct Data Sheets 6. Tosas Prod uct Spec i fi ca tions for Bitukote Data Sheet #B4 7. AAPA Pave ment work tips No 3 Sept 000: Sprayed Seal ing Ag gre gate Precoating 5

Sabita mem bers Or di nary Mem bers AJ Broom Road Prod ucts (Pty) Ltd Akasia Road Sur fac ing (Pty) Ltd Bitumen Construction Services (Pvt) Ltd Bi tu men Sup plies & Ser vices (Pty) Ltd Black Top Hold ings (Pty) Ltd BP SA (Pty) Ltd Brisk As phalt Sur fac ing (Pty) Ltd Chev ron South Af rica (Pty) Ltd Co las SA (Pty) Ltd Engen Petroleum Ltd Javseal (Pty) Ltd Mill ing Techniks (Pty) Ltd More As phalt Much As phalt (Pty) Ltd Murray & Rob erts Con struc tion Ltd Na tional As phalt (Pty) Ltd Nikamandla Con struc tion (Pty) Ltd Nyanga Roads (Pty) Ltd Phambili Road Sur fac ing (Pty) Ltd Polokwane Sur fac ing (Pty) Ltd Rand Roads (a di vi sion of GrinakerLTA Ltd) Roadsmart (Pty) Ltd Sasol Oil (Pty) Ltd Shell SA Mar ket ing (Pty) Ltd Spray Pave (Pty) Ltd Tarfix (Pty) Ltd Tosas (Pty) Ltd To tal SA (Pty) Ltd Van Wyk Tar mac cc Zebra Bituminous Surfacing cc 6

As so ci ate Mem bers Africon Engineering International (Pty) Ltd Arcus Gibb (Pty) Ltd Asch Pro fes sional Ser vices (Pty) Ltd BCP En gi neers (Pty) Ltd BKS (Pty) Ltd Cape Peninsula University of Technology Dick King Lab Sup plies (Pty) Ltd Entech Con sul tants (Pty) Ltd GMH/CPP Consulting Engineers (Pty) Ltd Goba (Pty) Ltd Holcim SA (Pty) Ltd Iliso Con sult ing (Pty) Ltd Jeffares and Green (Pty) Ltd Kaymac (Pty) Ltd t/a Kaytech Lafarge South Af rica Ltd Lidwala Consulting Engineers (Pty) Ltd Ninham Shand (Pty) Ltd PD Naidoo and As so ci ates (Pty) Ltd Rankin Engineering Consultants Sasol Technology Fuels Research Sasol Wax (a di vi sion of SCI) Siyenza Engineers cc Specialised Road Technologies (Pty) Ltd Stewart Scott International (Pty) Ltd Tshepega Engineering (Pty) Ltd Unitrans Fuel and Chem i cal (Pty) Ltd Vaal University of Technology Vela VKE Con sult ing En gi neers (Pty) Ltd WSP SA Civil and Struc tural En gi neers (Pty) Ltd Af fil i ate Mem bers Beosumbar and Associates cc DMV Harri smith (Pty) Ltd Salphalt (Pty) Ltd The Syn thetic La tex Co (Pty) Ltd TPA Consulting cc 7

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