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asphaltNEWS Volume 31 Issue 2 August 2017
asphaltNEWS
Volume 31
Issue 2
August 2017
In this issue
CEO Overview 3
Performance Grade Binder Research 4-7
RPF Resolutions 9
Tribute to Dr S Emery 9
Alternative Bitumen Rubber Technology 10-14
Advanced Asphalt Briquette Competition 16-20
PG Specification for Emulsions 22-27
Geotextile Seals the Cracks 28
EME Performance Update 30-32
Honouring those that leave a Heritage 33
Controlling Silica Dust Exposure 35
List of Manuals 36
New Members 37
List of Sabita Members 37-39
Asphalt News is published by the Southern African Bitumen Association (Sabita),
a non-profit organisation sponsored by its members to serve all stakeholders
through engineering, service and education.
No articles, extracts, photographs or other elements of this publication may
be reproduced in any form whatsoever without the written permission of the
Southern African Bitumen Association
Editor: Hazel Brown
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CEO COMMENTS
Progress on rolling out infrastructure projects for betterment of services to communities, appear to be mired in what’s termed “supply change rules”. These complex and cumber-some processes have been developed under the guise of curbing or eliminating “irregular expenditure”. With the wave of media coverage on the ever growing corruption scandals one has to doubt the efficacy of these processes. Those that are in charge should realise that integrity can’t be built into a process…. It is the most valuable commodity that can’t be bought, yet it is free to those who have the courage to use it!
In a country with a diverse population as in South Africa, government policies will invariably be scrutinized through the lens of one’s background and experience. In the absence of any deliberate and structured nation building, this could lead to polarization of the various communities. Nation building is one of the big-gest asks of any country’s leaders and it tends to be the most rewarding in the long term, both materi-ally and psychologically. Yet it hardly features on the agenda of many countries.
It might be that the “long term” does not sit well with current political agendas which tend to only fo-cus on the next election. Herein lies the difference between leaders and politicians……… leaders have a long term vision with willing followers whereas politicians have beneficiaries. And it is these very short termed focus politicians that have been entrusted world-wide to rule societies. Surely a drastic values based change is necessary.
From the soapbox onto the asphalt…
In this issue we look at the incorporation of emulsion binders into the proposed Performance Grade Specifications with the NCHRP research report 837 providing a strong lead. With a firm eye on to what future specifications might require, areas of further research underway are also detailed.
With the Briquette Competition now firmly entrenched in the Civil Engineering curriculum at Stellen-bosch University, this popular event continues to create great excitement amongst the students. See page 16 for more details.
A little more than a year has passed since EME was placed on the truck crawling lane leading from the Huguenot Tunnel to the toll plaza on the N1. We have a good look at how this durable pavement has stood up to the heavily trafficked challenge.
The planning for CAPSA 2019 has kicked off and we look forward to keeping you informed of develop-ments on this not to be missed event.
We also honor Dennis Rossmann for his inspirational dedication to the Industry.
Saied Solomons
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The advent of drafting binder Performance Grade PG specifications by the Road and Pavement Forum Working Group in October 2015, generated a ripple effect of needs for rheological research at an industry and academic level. Consequently, two Rheology Master Classes were presented in South Africa by Dr Geoffrey Rowe, one at SANRAL Head Office in June 2016 with Dr John D’Angelo as co-presenter and another one at Stellenbosch University in April 2017.
Introduction
The Master Classes defined the transition from development to implementation of the PG spec. This shift necessitated the chair to be a practical industry representative. The new Working Group chair, Steph Bredenhann of SANRAL, shifted the focus to closing the knowledge gaps in rheological data as identified by the international experts.
Research needs to identify compliance limits and to validate the decisions taken to draft the new PG Binder Specifications were tackled in a lead group.
Bredenhann, seconded to Stellenbosch University on a part-time basis, formed a working relation with the SANRAL Chair, Professor Kim Jenkins. Similar discussions were extended to CSIR. Together, they are driving PG binder research projects which will provide specification validations. Eight research projects (RP) are currently being conducted at Stellenbosch University:
1. PG Specification of typical seal binders from suppliers
2. Age related cracking of in-service, recovered seal binders
3. Bitumen mastic rheology for cape seals
4. Chip seal performance models
5. Storage stability of polymer modified binders
6. PG Specification of asphalt binders and fatigue testing
7. Thermal and traffic fatigue of asphalt binders
8. Quality control testing of asphalt binders on site
Each RP is uniquely designed to contribute towards specific grey areas of the PG specification. SANRAL further rallied industry to partake in the research program and Much Asphalt responded in appointing Dr Johan Gerber to manage the collective binder research at Stellenbosch University, while granting special access for the students to their Eersterivier Asphalt Laboratory.
Other responses were received from Colas, who also granted students access to their laboratory in Epping Industria, Tosas who supplies binders for research, National Asphalt provided lab assistance and SABITA who provides additional financial assistance.
PG BINDER RESEARCH AT STELLENBOSCH UNIVERSITY
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Figure 1: Summary of the eight research projects (RP) on seal and asphalt binder at Stellenbosch University
RP 1: PG Specification on supplied Seal Binders
The aim of this research project is the validation of seal binders within the PG spec. This includes the PG 70-10 specification and other typical seal binders obtained from suppliers with the exclusion of bitumen rubber SR-1. Investigation is conducted on binder response at different ageing ratios, using the dynamic shear rheometer (DSR). Binders are age conditioned using the rolling thin film oven (RTFO) and the pressure ageing vessel (PAV). PG 70-10 specification requires only one PAV cycle, however, binder ageing is conducted up to four PAV cycles to simulate longer term behaviour. Multiple stress creep recovery (MSCR) tests are conducted to examine the contribution of polymers towards shear deformation elastic recovery in polymer modified binders (PMB), hence, determining the creep compliance component, JNR.
The final aspect of this study is the quantification of the reduction in binder relaxation with ageing i.e. susceptibility to durability cracking. Bending beam rheometer (BBR) tests are therefore conducted from 0°C at -6°C intervals up to -30°C. The specification parameter ΔTC is determined from the BBR tests which serves as a rheological indicator for cracking.
RP 2: Age related cracking of recovered seal binders
Where RP 1 includes analyses on artificial ageing of binders from the suppliers, the aim of RP 2 is to establish ageing ratios from field recovered seal binders and link the ratios with binder susceptibility to durability cracking. Seal binders are recovered from field specimens using solvents, followed by centrifuge treatment to remove filler. The solvent is then vaporised (Rotavapor method), yielding a recovered seal binder. BBR tests are conducted on the field samples to determine ΔTC values (indicator for cracking), while DSR tests are conducted to obtain the recovered binder’s rheological response after several years in-service. The Glover-Rowe parameter (G-R) is calculated from the DSR data, which gauges the resistance of the binder to fatigue cracking. These results are all superimposed on field observed cracking as will be discussed in RP 4. This is where RP 2 overlaps with RP 4, combining laboratory work with empirical field research and observations.
PG BIN
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RP 3: Bitumen Mastic Rheology for Cape Seals
An aspect that has been neglected over the last couple of years in South Africa is the rheology properties of slurries for Cape Seals. In this research project, slurries are reduced to mastic by removing the aggregate above the 0.3 mm sieve fraction. Anionic stable grade emulsion (SS60) is mixed with different ratios of fine material and cement.
The aim of this research is to quantify the response properties of the mastic using DSR and BBR testing. In this way, the influence of cement and slurry grading on stiffness response at a range of temperatures and loading times, can be examined. Mastics are considered to become brittle with ageing. This needs to be quantified. In conducting MSCR tests, the amount of shear deformation and elastic recovery is measured. It is expected that this research project would produce mastic material models implementable in finite element programs to advance the field of numerical seal modelling.
RP 4: Chip Seal Performance Models
This research project follows a mechanistic-empirical approach in developing chip seal performance models by incorporating laboratory as well as field data. A key functional aspect of a seal is the prevention of water ingress into the base layer. Therefore, this research is focused on developing a fatigue cracking model that is able to assess the service life intervals for cracks to develop and water ingress to initiate. Using a partially empirical approach, the model includes falling weight deflectometer measurements, visual surveys of crack initiation, traffic volumes and growth, traffic classes, environmental and regional influences. Using a mechanistic approach the model incorporates four point bending beam tests of seal specimens, BBR and DSR data of the recovered binders from seal specimens and finite element modelling predictions.
RP 5: Storage Stability of Polymer Modified Binders
Storage stability of PMBs refers to a polymer tendency to sediment within a binder over time, accumulating at the bottom during storage. The compliance limit for storage stability was tentatively set at 10% in the PG specification. This means that the difference in performance parameter results between the top and bottom samples of a tank may not deviate by more than 10%. The aim of this research project is to validate the compliance limit for storage stability of typical South African homogeneous PMBs. This research considers base binders from the various South African refineries with SBS modification of 1% to 4% and EVA modification of 3% to 6%. Samples are blended and stored in vertical glass tubes at 58°C, 64°C and 70°C from 0 hours at set intervals of 24 hours going up to 72 hours. At the set interval, samples are separated into 3 sections followed by DSR testing of the top and bottom sections. The difference in the complex shear modulus may not exceed 10%.
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Figure 2: BBR depiction and binder beam bending illustration
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RP 6: PG Specification on supplied Asphalt Binders
The aim of this research project is similar to RP 1, with the difference that typical asphalt binders from suppliers are being validated in accordance with the PG specification. In addition the rheological parameters that can be related to loading fatigue, are evaluated. The study focuses on the PG 64-16 and PG 58-22 specification with the exclusion of bitumen rubber at this stage. Binder response towards ageing ratios is investigated with the DSR for unaged, RTFO and one to four PAV ageing cycles. Shear deformation and elastic recovery properties are obtained by conducting MSCR tests and determining the creep compliance component, JNR. Susceptibility to durability cracking is determined from the BBR tests by calculating ΔTC. These rheological parameters will be related to asphalt fatigue based on four point bending beam testing on a typical asphalt mix grading.
RP 7: Thermal Fatigue of Asphalt Binders
An asphalt binder cracking device (ABCD) setup consists of an inner invar ring with a film of binder around it much like a rim and tyre setup. The invar-steel ring is fitted with strain gauges and due to the difference in material stiffness of steel and bitumen, binder deformation as a result of thermal loading is observed. This research project aims to develop a thermal damage model for asphalt binders that is also able to indicate a single event fracture crack in the case of extreme cooling rates. Investigations are conducted on unaged, RTFO and one to four PAV cycle aged binders.
RP 8: On-Site Quality Control of Asphalt Binders
The changes introduced by the PG specification introduces a need to assure quality on site. Since new specification qualities are primarily determined from DSR measurements before dispatching the binder to site, a similar type of evaluation needs to be conducted on-site. Both field conditions and economics militate against sensitive, sophisticated and costly equipment being used on site. Rheological equipment is too expensive to insist that site labs have to acquire e.g. a DSR, for quality assurances. This research project aims to develop relationships between existing on-site tests like: penetration, ring and ball and rotational viscometer with PG specification compliances. The outcome of this study will aim to ensure the optimal site equipment in terms of a balance between test reliability and cost.
CONCLUSIONS
An integrated working group consisting of experienced pavement engineers, industry bodies, binder and asphalt suppliers and academics is committed to resolve any deficiencies drafted into the PG binder specification. Binder research that extends beyond the scope of PG binder compliance, is required to achieve this goal. The two main focus areas of application are those of seal and asphalt binders. This represents PG 70-10, PG 64-16 and PG 58-12 as the array of binders. Seal binder research consists of PG specification testing with an emphasis on binder ageing, mastics for Cape Seals, seal cracking performance models, and binder storage stability. The latter overlaps with the asphalt binder research which includes PG specification testing with an emphasis on binder fatigue, and on-site quality control measurements.
In closing, the PG binder initiative is captured in the words of SABITA CEO, Saied Solomons: “Close cooperation is an enduring characteristic of South African Padmakers (road builders) and will get this initiative to work.”
Figure 3: DSR depiction and binder sample illustration
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The resolutions formed at the 33rd RPF held on 9th – 10th May are as follows:
1. RPF to assist with the establishment of a new Working Committee for Cementitiously Stabilised Road Materials in respect of TRH13.
2. RPF to assist with further developments towards practical characteristics, i.e. transfer functions (or limiting tensile strain values) for empirical-mechanistic (M-E) design of relatively high stiffness bituminous roads base materials.
3. Sabita (through RPF) to assist with the certification process of Cold Mix asphalt, i.e. developing technical guidelines towards Agrément certification.
4. Proposal towards acceptance of a new SANS Standard BT25- Binder Distribution Calibration.
Many long-standing attendees of the Road Pavement Forum will remember Dr Steve Emery who delivered a number of technical papers at this forum. It is with regret that we were informed of Dr Emery’s passing on the 3rd April, 2017 via one of Sabita’s Council members, Ms Angela Broom and would like to pay homage to this technical specialist, well known by many of you in the industry.
Dr Emery has been known as one of the most respected and accomplished expert in his field. As a specialist consultant with wide-ranging engineering, technical and commercial expertise earned during the course of 39 years in the fields of road and airport engineering. Prior to moving to Australia, during his time in South Africa he held the following positions: Honorary Professor, Department of Civil Engineering (University of the Witwatersrand); Group Technical Director (Colas SA (Pty) Ltd); Professor & Sabita Chair of the Asphalt Pavement Engineering committee whilst at the University of Stellenbosch and was a Senior Research Engineer at the CSIR.
Key areas of expertise include roads, pavements, materials, bitumen, asphalt, airports, diagnostic engineering and research, multi-faceted and multi-disciplinary projects, commercial practice, and engineering education. Several of Dr Emery’s papers have also been published in the 6th, 7th, 8th, 10th and 11th CAPSA proceedings spanning over some 24 years. In respect of Sabita’s publications, Dr Emery has contributed to the first editions of manuals 7, 9, 10, 11 and 12.
We salute his tremendous contribution to the industry.
ROAD PAVEMENT FORUM
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Bitumen rubber (BR) has been used successfully in southern Africa since the early 1980s. Many municipalities, provincial authorities and clients at national level are now embracing alternative bitumen rubber technologies based on “game changing” developments in New Crumbed Rubber Technology (NCRT), says Herman Marais, director – Plant & Technical at Much Asphalt.
A paper titled “Latest developments in crumb rubber modified bitumen for use in asphalt and seals - the South African experience” was recently prepared by representatives of Much Asphalt, Tosas and Wim Hofsink Civil Engineering Services for the 17th AAPA International Flexible Pavements Conference which took place from 13 to 16 August 2017. Part of this paper is shared here.
The paper makes the point that bitumen rubber is used extensively in South African asphalt products, not only due to its increased fatigue resistance and reduction in ageing of the binder but also the environmental advantages of reducing and reusing waste material. “There have also been exciting developments in low temperature bitumen rubber technology aimed at reducing the risks associated with the use of the premium product” Marais points out.
What is bitumen rubber?
Bitumen rubber is a blend of bitumen, rubber crumbs and extender oils with specific properties manufactured under highly controlled conditions.
Digestion of the rubber crumb occurs in stages as the rubber particle is progressively converted from a resilient particle to a gel and finally to an oil. Each phase plays a role in the performance of the bitumen rubber. The elastomeric particle provides resilience, the gel increases the softening point and viscosity, and the oil phase improves durability and flexibility.
The source, grading and morphology of the rubber particles will also affect the degree of chemical reaction and therefore the binder performance properties.
Rubber from truck tyres is more reactive as these have higher natural rubber content. Fine particles disperse better within the bitumen, while large particles tend to remain largely undissolved and float in the bitumen. Buffings ground at ambient temperature have a more amorphous surface compared with those that are cryogenically produced and are thus more absorptive.
The major risk associated with bitumen rubber has always been the limited shelf-life, which is influenced by factors such as temperature, time, pressure during circulation, agitation, rate of heating, crumb size, crumb composition and crumb shape.
The shelf-life of bitumen rubber for use in asphalt is typically longer as the binder is handled much more gently than during chip seal applications where it is heated and circulated through the spray bar at elevated temperatures to heat up the spray bar. The binder then degrades quicker, not only due to temperature but also due to the speed of circulation through the spray bar.
Bitumen rubber in South Africa
The success of bitumen rubber in both chip seals and asphalt applications in the past 30 years has led to increased use on most of the freeways around South Africa. It is particularly favoured by toll road concessionaires due to reduced life cycle cost using bitumen rubber, even with a higher initial input cost.
ALTERNATIVE BITUMEN RUBBER TECHNOLOGY
with WARM MIX ASPHALT BENEFITS
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EFITSThe largest quantity of bitumen rubber used for a single project in South Africa was on the Gauteng Freeway Improvement Project between 2009 and 2011, for which in excess of 400 000 tonnes of bitumen rubber asphalt were supplied.
However bitumen rubber has been mainly used in single and double seal applications on existing bituminous surfaced roads as reseals and stress absorbing membranes (SAMs) or interlayers (SAMIs).
Composition of bitumen rubber
Bitumen rubber in South Africa typically consists of bitumen (78%), rubber crumbs (20%), and extender oil (2%). The ratio and percentage of various components may be adjusted depending on the source and grade of bitumen, the area and the season.
Selection of quality raw materials adds desirable properties to the product and improves performance. The grading, morphology, type and source of rubber crumbs are controlled and specified since they influence the reactivity and elastic properties of the end product. The crumbed rubber contains approximately 40% carbon black, a natural anti-oxidant that is proven to delay ageing of the bitumen rubber binder on the road.
Bitumen rubber, due to its higher viscosity, is handled at between 195 and 215°C.
Bitumen rubber in asphalt applications
Bitumen rubber asphalt (BRA) is predominantly used as a gap graded or continuously graded asphalt mix. The continuously graded envelope is slightly coarser in the fine sand fraction to accommodate the crumbs in the combined grading.
In the past few years bitumen rubber ultra-thin friction course (BRUTFC) has been used very successfully on freeways, provincial and urban roads and airport runways.
Picture 1: UTFC paving trial on Upington airport runway
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The BRUTFC has performed well and the open graded stone skeleton added excellent noise reduction and improved visibility in rainy conditions, as well as improved skid resistance.
Trans African Concessions (TRAC) carried out BRUTFC trials on a section of the N4 freeway near Silver Lakes Estate East of Pretoria and the improved riding quality and reduced road noise on this section led to the full freeway subsequently being overlaid with BRUTFC from Pretoria to Bronkhorstspruit.
New Crumbed Rubber Technology
In-depth and continuous research on testing for all modified binders has led to the development of several specifications and guidelines over the years, most recently the New Crumbed Rubber Technology (NCRT). Compression recovery and resilience properties are equivalent to conventional bitumen rubber, but viscosity, softening point and flow tests are unique to alternative bitumen rubber due to its specific composition.
After several years of R&D in Germany and then South Africa, followed by the production of trial blends, laboratory asphalt designs and a plant trial at Much Asphalt Roodepoort, a successful section of New Crumbed Rubber Technology (NCRT) was placed on the Misgund rehabilitation project on the N1 freeway south of Johannesburg in November 2012.
During the Maximising Seal Work Trials in June 2012, NCRT was also successfully used in a chip seal application. The advantages of the concept in South Africa were further entrenched in 2014 and 2015 with several more trial sections on the N3 near Warden, various streets in Bloemfontein, and a SANRAL project from Manguzi to the Mozambique border.
By 2016 and 2017 practitioners and road authorities were welcoming the reduced risk and improved operational efficiency becoming evident through the NCRT trials. More chip seal contracts near Zeerust in the North West Province, Langebaan in the Western Cape, Nanaga and Komga in the Eastern Cape and Volksrust in Mpumalanga were converted from conventional bitumen rubber to NCRT.
Flexibility of supply and demand due to elimination of high cost of on-site plant establishment made smaller contracts for bitumen rubber demand more feasible. In projects supplied by Much Asphalt including a road on a steep incline in Plettenberg Bay and Baden Powell Drive among others in Cape Town, warm mix asphalt has been very successfully substituted in both the use of NCRT in UTFC and dense graded asphalt applications.
Picture 2: Skid resistance testing of NCRT Gap Graded trial on the N1 south of Johannesburg
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The increase in compaction window with the reduction in manufacturing and paving temperatures varied on the mix and aggregate type.
In addition to improved rheological behaviour of the NCRT binder (relative to conventional bitumen rubber), the most beneficial advantages are the improvement of shelf-life and remarkable storage stability.
Bitumen rubber typically had a storage life of six to eight hours in chip seal applications and beyond 14 hours in asphalt applications under more gentle controlled conditions. However NCRT has been proven on laboratory and full plant scale to have storage stability at 150°C and application temperatures of 180°C for more than 10 days.
Gentle agitation is still required to suspend the non-homogenous binder. Prolonged pumping unfortunately degraded the thermally stable NCRT due to mechanical action.
The differences between the improved properties of low temperature and longer life bitumen rubber across various South African suppliers were compared and in June 2017 the Road Pavement Forum’s Bitumen Materials Committee proposed an addendum to the TG 1 guideline and suggested the limits for S-R2 and A-R2 in the table overleaf.
The request for this approval will tabled at the RPF in November 2017.
Picture 3: Bitumen rubber UTFC with NCRT applied as warm mix asphalt in a recent project in Plettenburg Bay
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The next stage of practical rollout of new rubber technologies will involve a more homogenous type of bitumen rubber that closely resembles the polymer modified binder behaviour.
Typical specifications and guidelines used in South Africa for non-homogenous binders
Property UnitTest Method S-R1 S-R2* A-R1 A-R2*
(Chip Seals) (Asphalt)
Softening point¹ °C MB-17 55 - 65 65 - 80 55 - 65 65 - 80
Dynamic viscosity @ 190°C dPa.s MB-13 20 - 40 20 - 50
Dynamic viscosity @ 170°C* dPa.s MB-13 10 - 40 10 - 40
Compression recovery
5 min.
% MB-11
>70 >70 >80 >70
1 hour >70 >70 >70 >70
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hours>40 >40
4 days >40 n/a
Resilience @ 25°C % MB-10 13 - 35 10 - 40 13 - 40 10 - 40
Flow at 60°C Mm MB-12 15 - 70 10 - 50
Flow at 70°C* Mm MB-12 10 - 40 10 - 40
If longer shelf-life is desired and improved rheological properties are required, the recently developed New Crumbed Rubber Technology (NCRT) can be considered to provide practitioners with a well-balanced binder with enhanced properties.
“The new NCRT product proves that there are exciting opportunities to be considered,” says Marais. “This hybrid technology provides the best of both worlds, combining warm mix asphalt with bitumen rubber properties and behaviour.”
Picture 4: Warm mix Asphalt with NCRT in Plettenburg Bay
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Data Acquisition as standard
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The show goes on
2016 earmarked a successful launch of the 1st Annual Asphalt Briquette Competition. It was held amongst the fourth year students at Stellenbosch University, as part of their practical experience in Transportation Engineering. Expanding this success into the senior students later in 2016 included the launch of an advanced competition for the Postgraduate Pavement Engineering group, made possible by the benevolent support of sponsors (BVi Consulting Engineers and Much Asphalt).
Sabita’s vision in promoting Asphalt Technology as a key specialist field of pavement engineering and at the same time capturing the interest of our future generation of engineers, amounts to casting a broader net that is paying dividends. At all levels, students and practitioners alike, are rarely exposed to the mix design process at such a practical level, instilling fundamental principles.
Dovetailing the undergraduate and postgraduate competitions has provided a foundation for improvements. In so doing, the second generation competition for undergrads has become a highlight of their year. The 2017 competition was met with infectious enthusiasm and healthy competitiveness. Each group warning the rest that their mix is the winning combination!
The 2017 competition included twenty-one groups of six members each. The choice of partners-in-crime was left to the devices of the initiators and the gravitas of group dynamics.
The competition was designed to nurture an understanding of manner in which performance related properties such as strength, volumetrics and durability are offset against each other. Ultimately, finding the best balance is what matters. The battle is only won if this principle is instilled in the undergrads.
Re-defining the Challenge
Of course no challenge is perfect without an unanticipated curve ball and SU organisers decided to tighten the allowable envelope for air voids (previously 4-6%), to place greater emphasis on durability. This rule adjustment from the previous year, provided two objectives (Figure 1):
• Design the strongest mix measured in terms of the Indirect Tensile Strength and;
• Ensure durability, by limiting air voids to between 3.5 and 4.5%. If the specimens fall outside of these boundaries a penalty multiplication factor of 0.8 is applied to the highest ITS.
ADVANCED ASPHALT BRIQUETTE COMPETITION
Stellenbosch University in collaboration with Sabita, BVi Consulting Engineers and
Much Asphalt (Pty) Ltd
Figure 1: Measurement Criteria defined for the 2nd Asphalt Briquette Competition – 2 in total
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Strategic planning by students (Photo 1a) formed a precursor to implementation (Photo 1b)
A Colto Medium mix a continuous grading of aggregate along with known asphalt mix properties (70/100 binder, voids versus binder content @ Ndes, compaction temperature = 150°C and aggregate SG) was provided. The new task:
• Use this information to design a new mix using 70/100 binder,
• Make possible adjustments to grading (selected fractions were provided), binder, cement and/or lime,
• Aim to achieve the highest ITS, with target voids between 3.5-4.5% and compacted at the same temperature.
Guided by the performance measures, each group selected and prepared two mixes. The mixes are titled the “Standard” grading (with variable bitumen content) and the “Joker” (varied grading and composition) with each aiming to attain optimal points for performance.
Implementation of the mix designs provides no rest for the students. Laboratory mixing must be done by hand, to obtain a first-hand feel of the consistency and workability of the various compositions. Mix design is incomplete without dirtying your hands at the coal-face!
ADVANCED ASPHALT BRIQUETTE COMPETITION
Photo 1(a): No project is successful without careful planning!!
Photo 2(a): From taking the job extremely serious
(b): to enjoying the on-job training
(b): Putting planning into action
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N Some, of course, took it the extra mile, applying “asphalt chef” skills. Ultimately, it is a group effort, where the whole is greater than the sum of the parts, both for the groups and the mixes.
Of course no learning curve is complete without a few mishaps on the way! Perseverance and perfection are not initially congruent (Photo 3a), but true perseverance has no limits (Photo 3b).
Photo 3 (a) If at first you do not succeed –
(b) try and try again!!
Success!
oopsie.......
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Crowning the Champs – 2017
To end off the competition, a closing function with the generous sponsorship of BVI and Much Asphalt was held.
The prizes for each category were:
• 1st Place: R 6 000 /group
• 2nd Place: R 3 000 /group
• 3rd Place: R 1 800 /group
Before the closing function, each group’s specimens for both the Standard and the Joker were stored under lock-and-key and then conditioned before testing. Real time streaming of the results were projected on computer screens at the function, to maximise the suspense in the anticipation of the winning mixes. Only when the final result was processed, was the winning group announced.
The suspense of such competition is balanced with “karma” created by holding onto the anticipated winning specimens (of various forms) (Photo 5).
In the end the results always prevail. Obvious winners in the beginning, when the durability factor of 0.8 was not yet applied, did not end up as ultimate winners!
The final competition results revealed the “Standard” mix won out. Sometimes precision and perfection trump the artistic flare
Only the third place winners achieved a winning result with the Joker design! It seems that the penalty for durability a lesson hard learned.
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Photo 4: Refreshments needed to keep the strength
Photo 5: Maybe “karma” will provide the winning combination –we wonder..
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The winning combination was a blend of many variables, but finesse in the mix was certainly a large component. Group 4 was certainly pleased to be Crowned Winners for 2017 (Photo 6 below)! There must have been something in the art of fine touches to a good mix? Well done ladies and gents, our future is in excellent hands!
Conclusion and Outcomes
Another successful execution of the Asphalt Briquette Competition has delivered favourable outcomes:
• Exposure to the application of sound fundamental knowledge put into practice.
• Most importantly, designing solely for strength is not the final solution. Many other factors such as durability play an important role and executed in the application of these design principles;
• Understanding that even at the most fundamental level, a good understanding of the key variables is needed; and
• Exposure to the asphalt industry and opportunities to benefit from the source of experience.
The importance in the role of the whole chain of design certainly plays a significant role…. engineering is not just a numbers game ...The winners of the competition can certainly attest to this!! But maybe of most importance our 2017 group of undergraduates is that little better equipped to face the challenges of tomorrow whilst having fun along the way!! After all the best things are not only learnt through making mistakes...some can even be learnt by enjoying the process.
Thanks once again BVi and Much Asphalt. This would not have been possible without your generous sponsorship and investment into our graduates’ future
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VAN
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SPHA
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Figure 2: ITS results after 0.8 factor has been applied – both for “Standard” and “Joker”
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Leading Asphalt manufacturers and suppliers in Southern Africa
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SUSTAINABILITY IS AT THE CORE OF OUR BUSINESS PRACTICES
22
A concern frequently raised in debates during the introduction of a PG specification in SA was that the damage resistance characteristics defined and adopted in the PG framework were based solely on work done on asphalt, not chip seals nor microsurfacings. In this respect, the publication of the NCHRP research report 837: Performance-Related Specifications for Emulsified Asphaltic Binders Used in Preservation Surface Treatments was interesting as it dealt with the performance of bitumen emulsion residues in chip seals, microsurfacings and spray seals (e.g. enrichment sprays). The research reported in the document, carried out under the guidance of Richard Kim (North Carolina State University) and Hussain Bahia (University of Wisconsin-Madison), is enlightening and may well provide guidance to SA practice to gauge the extent to which adequate performance of binders in seals are safeguarded by the present specification framework.
This article penned by Mr. P.A. Myburgh presents some content of the report that may be considered as a prelude to a deeper study of the prospects for, at most, a simple addendum to the technical specification developed to date. While the focus here is on the performance characteristics of the residual binder of emulsions, other matters within the report – related to the storage and handling of emulsions – could also be considered with the view of updating the current SABS specifications for this type of binder.
A survey conducted by Johnston and King (2008) identified the need to develop a climate-driven, performance-related grading system for bitumen emulsions used in preservative surface treatments (PST) i.e. chip seals, spray seals and microsurfacings. As is the case for PG grades, emulsion performance grade (EPG) specifications aim to address properties that correlate with critical PST performance measures taking account of the climatic and traffic loading conditions.
Chip Seal Distresses
Three distress types of chip seal in order of importance are: i. Ravelling (aggregate loss); ii. Bleeding; and, iii. Rutting (in multi-layered seals).
Ravelling (or aggregate loss) was deemed to be the most critical performance characteristic because of its consequences. Three phases were identified:
• Early ravelling resulting from the inadequate curing of an emulsion prior to opening to traffic.• Longer term ravelling resulting from trafficking at intermediate and low temperatures:
- at an intermediate temperature, the aggregate loss is due primarily to the loss of the bond between the binder and the aggregate.
- at a low temperature, aggregate loss is deemed to be due to the cohesive fracture of the brittle bitumen residue.
• Wet ravelling that occurs due to moisture damage to the binder which can lead to a significant reduction of the adhesive bond between the residue and the aggregate.
The proposed EPG specifications address low-temperature ravelling only. It is suggested that intermediate temperature behaviour should be assessed during the materials design stage, using the bitumen bond strength (BBS) test, a modification of AASHTO TP91.
Bleeding is ranked as the second most critical distress and is caused by:
• Loss of aggregate which manifests itself as bare (bleed) spots, providing little frictional resistance.
• Excessive richness in the wheel path which also contributes to loss of friction that can become a safety hazard for drivers.
(The document makes the point that, although the terms ‘bleeding’ and ‘flushing’ are often used
REPORT ON A PERFORMANCE GRADE SPECIFICATION FOR EMULSIONS MAY GIVE GUIDANCE TO SA
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interchangeably in the literature, the mechanism behind flushing is construction/design-related (e.g., excessive binder, undue chip embedment or insufficient aggregate), whereas bleeding is related directly to the viscoplasticity of the binder at high temperatures. Therefore, only bleeding is considered as a critical distress in the development of the bituminous binder EPG specifications for chip seals.)
Microsurfacing Distresses
Distresses types that are critical for the assessment of microsurfacing are ranked as follows: i. Ravelling; ii. Bleeding; iii. Rutting; and, iv. Thermal cracking.
Again, only distresses that relate directly to binder performance were considered. As is the case with chip seals, ravelling is driven by factors related to the aggregate and aggregate / binder system and cannot be captured by binder testing alone. Reflective cracking distress is also not considered for microsurfacing as it relates more to the structural integrity of the substrate.
The rutting potential in microsurfacing is related to the visco-plasticity of the residual binder at high temperatures whereas thermal cracking in the mixture is related to the stiffness and thermal stress relaxation capabilities of the binder at low (winter) temperatures.
Test Methods
In developing the EPG specifications, test methods were identified that address both the fresh emulsion properties related to the storage and constructability and binder residue properties that are related to performance. Figure 1 presents the test methods in the proposed EPG specifications.
Figure 1: EPG specification test methods
Source: National Academy of Sciences
Traffic
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SA The EPG specification compliance limits are related to expected traffic. After due consideration and
study, the following traffic classes are proposed:
• Low Traffic: 0 – 500 AADT
• Medium Traffic: 501 – 2,500 AADT
• High Traffic: 2,501 – 20,000 AADT
The upper limit of 20,000 is based on research carried out in 2005 as well as the research team’s own experience. Although chip seals have been constructed at AADT counts in excess of 20,000 in the USA, their adequate performance was deemed to be influenced by factors such as local aggregate quality and expertise and hence the upper limit of 20,000 was adopted for general application.
Grading Temperature
High-temperature asphalt PG requirements for a given location are determined using a model based on a depth of 20 mm in asphalt and an assumed threshold for allowable rut depth of 12.7 mm, typically based on 98% statistical reliability of climate data.
It was found that the difference between the temperature of a pavement at its surface and that at a depth of 20 mm is 3.9°C. Therefore it was determined that for EPG specifications, surface temperature grade increments should be shifted 3°C from the existing HMA PG specification grade increments.1 Thus, in relation to the existing HMA performance high-temperature grades of PG 58, PG 64, PG 70, etc., the EPG specifications recommend the use of high-temperature grades of EPG 61, EPG 67, EPG 73, etc.
It is noted in the report that this change in the specification grade does not mean that the PG grade of the base bitumen used to fabricate the emulsion would necessarily be higher. In fact, all of the emulsions tested were made from an original base bitumen with a high-temperature PG grade of either 58°C or 64°C, yet every emulsion tested had a higher temperature grade in the EPG specifications than the original base bitumen PG used to fabricate the emulsion. (In the conditioning described by AASHTO PP 72, Method B a 380 µm emulsion film is cured in a forced draft oven for six hours at 60°C. The residue thickness after curing can vary from about 190 to 300 μm.).
Chip Seal Residue Binder Tests
The critical distresses for chip seals and the associated test methods for evaluating residual bituminous binder – using only a DSR – are listed in Table 1.
Table 1: Tests on bituminous binder residue for chip seals
Performance characteristic Test method Parameter(s) Measured
Bleeding at high temperature MSCR (AASHTO T 350)Non-recoverable Creep Compliance, Jnr
Ravelling at low temperature DSR Frequency sweepDynamic Shear Modulus (G*) at δcritical
The test methods were selected on the basis of research during 2001 and 2012 and allow for the evaluation of the binder under conditions that reflect various climatic and traffic conditions incorporated in the EPG specifications.
1While a shift of 4°C would adhere more closely to expected temperature gradients, it was deemed more practical to use the 3°C shift as the PG specifications adopted 6°C increments.
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Bleeding at high temperatures
A strong correlation was found to exist between MSCR Jnr values and high-temperature performance for chip seals. To verify that the relationship between Jnr values and bleeding, the chip seal performance that was measured using the one-third scale model mobile load simulator (MMLS3). The 80% maximum bleeding limit for chip seals defines the amount of bleeding under MMLS3 loading that, when exceeded, is unacceptable for chip seal performance.
To allow for extrapolation (extension of temperature ranges beyond the constraints of the MMLS and degree of bleeding) curves were fitted which are shown in and compliance limits proposed as shown in Figure 2.
Figure 2: Compliance limits for chip seals high temperature grading
Source: National Academy of Sciences
Compliance limits developed accordingly are given in Table 2.
Table 2: High temperature compliance limits for chip seals
Traffic category Maximum Jnr @ 3.2 kPa (kPa-1) at Tmax
Low 8
Medium 5.5
High 3.5
Low temperature chip loss
Studies showed that S(60), m(60), and the creep stiffness at 8 seconds, S(8), were binder-dependent, and inadequate for use in the proposed EPG specifications. The rheological residual binder property that demonstrated the strongest relationship to both chip seal aggregate loss and microsurfacing fracture energy is the dynamic shear modulus (G*) at a critical phase angle (δc), derived from DSR frequency sweeps from 5°C to 15°C. Figure 3 presents the results.
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Figure 3: Aggregate loss vs residual binder G* at a) δ = 45° and (b) adjusted δ as a function of temperature
Source: National Academy of Sciences
Residual binder compliance limits were based on the relationships between aggregate loss and G* values that correspond to the δc values and the established allowable aggregate loss thresholds for low, medium, and high traffic volumes. Figure 4 presents the results. The corresponding maximum G* limits for low, medium, and high traffic volumes are 30, 20, and 12 MPa, respectively.
Microsurfacing Residual Binder Testing
Rutting
As was the case for bleeding potential for chip seal residue, the resistance to rutting of micro surfacing residue was characterized using the Jnr value at the 3.2 kPa correlated with the mixture rutting measurements using the MMLS3 at low, medium, and high traffic volumes. A maximum allowable rutting threshold of 5 mm (based on scaling) for laboratory-tested mixture specimens was utilized in the development of the preliminary specification limits.
The preliminary specification limits derived for the medium and high traffic volumes were found to be similar due to the effect that, after a large number of traffic repetitions, the thin microsurfacing mixture can no longer continue to densify beyond the values achieved at the medium traffic level. Therefore, one maximum Jnr limit will define acceptable performance for both high and medium traffic volumes for the microsurfacing EPG specifications. (See Table 3).
Table 3: compliance limits for rutting of microsurfacings
EPG Specification Traffic Grade Maximum Jnr @ 3.2 kPaLow 5.0 kPa-1
Medium/High 1.5 kPa-1
Figure 4: Maximum G* for chip seal residual binders Source: National Academy of Sciences
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Thermal cracking
Thermal cracking of microsurfacings was found in general to occur during the first winter after construction. Consequently, properties of the unaged binder were used to establish criteria for low temperature grading. Following tests using the Single-Edge Notched Beam (SENB) test to establish critical performance thresholds for microsurfacing fracture energy a performance limit for fracture energy of 0.0010 J was established i.e. the fracture energy at the glass transition temperature.
The critical phase angle values for microsurfacing residual binders were established in a procedure analogous to that used for chip seal residual binders. Good correlation was found between fracture energy and G* values at δc, irrespective of mixture test temperature as shown in Figure 5. Accordingly the upper limit of G* at δc of 16 MPa is proposed.
Prospects
While it is unthinkable that SA should develop distinct performance grade specifications for asphalt, on the one hand, and seals on the other, it is also imperative that there is assurance that binders complying with the proposed PG specification will perform satisfactorily in seals, under the prevailing circumstances of traffic and climate. After all, a large proportion of bitumen in this country is applied in chip seals, slurries and the like. Clearly, a factor that should be taken into account is the fact that, for binder grading purposes, the surface temperature of bituminous layers may be several degrees higher than those adopted for the 20 mm depth in the PG grading framework. While one can continue to perform the MSCR test at the appropriate PG grading temperatures, there should be assurance the binder will comply with a maximum JNR compliance limit at the elevated temperature. To this end, characteristic temperature susceptibility of non-recoverable compliance of SA binders would need to be investigated.
As far as loss of (low temperature) cohesive strength and thermal fracture characteristics of the binder are concerned it is not possible, at this stage, to make comparisons with the requirements of the PG specification, since no criteria have yet been developed. However, the approaches adopted by the research teams in the project reported in NCHRP merit consideration, especially in local research aimed at the application of bituminous binder rheology concepts which future mentors of research should be mindful of.
Figure 5: Correlation of G*@ δc
Source: National Academy of Sciences
28
In early 2017, one of Kaytech’s distinguished geotextiles rescued a severely cracked section of road in North West Province. The site was Waterval Oos Ext 59, in Rustenburg, where a road, constructed approximately five years ago was in dire need of crack sealing. The product was Sealmac, a specialist paving fabric specifically designed for use in resurfacing roads or upgrading gravel roads.
Boshoff L J Eindomme appointed EPS Consulting Engineers to provide an effective and economical solution. Upon inspection of the road, the in-situ material was found to be a highly active clay commonly known as black turf. This caused swelling and shrinkage due to the moisture content fluctuations of the shoulder and roadbed materials during wet and dry cycles. The repetitive movement, in conjunction with aging asphalt and a complete lack of maintenance, resulted in longitudinal cracks forming. No other forms of deterioration such as rutting or potholes were detected.
Photo 1: Longitudinal cracks
The engineers readily specified Sealmac to seal the cracks and to form a waterproof barrier in the pavement. This is a continuous filament, nonwoven, double nee-dle-punched, geotextile manufactured from 100% recy-cled polyester. The continuous filament imparts a high isotropic strength while the needle-punching imparts several advantages including appreciable thickness for bitumen impregnation, high resistance to puncture, and a flexibility that greatly facilitates laying operations.
Contractor, Hasset Konstruksie commenced preparations by sweeping the road surface and blowing the longitudinal cracks with a compressor. Cracks larger than seven millimetres were filled with a crack seal mixture. A 1.1 litre/m2 tack coat, using an SS60 with 3% latex, was then applied to the surface. To cover the prepared area, 300 mm wide Sealmac strips (1 000 linear metres) were installed and worked into place using squeegees and brooms. Once installed the strips were treated with a 0.4 litre/m2 saturation coat. To eliminate tackiness and prevent pickup, a fine layer of crusher sand was then applied. At a later stage, a slurry seal completed the project.
This paving fabric effectively prevents surface water ingress, bridges shrinkage cracks, retards reflective cracking, reduces crack width and surface stripping, and stabilises pavement moisture content. In addition to all these properties, the lower construction costs, lower maintenance costs, prolonged fatigue life and reduced overlay thickness are significant benefits that put Sealmac into a class of its own.
GEOTEXTILE SEALS THE CRACKS
Photo 2: The completed surface
17 static plants • 5 mobile plants • extensive product range • stringent quality control • bitumen storage • industry training
OUR PEOPLE
OUR PEOPLE CAREMuch Asphalt is southern Africa’s largest manufacturer of hot and cold asphalt products.
Our people ensure that our customers get what they want, on time, to the highest specs, at the best possible price. No matter what. Much Asphalt people care. They are the custodians of our business for the future.
T: +27 21 900 4400F: +27 21 900 4468
30
It has been approximately 2 years since the successful construction of the first EME Asphalt Base in the Western Cape. Located north east of Paarl along the N1 truck crawler lane between the Huguenot Tunnel West Portal and the toll plaza, the EME was constructed along a route which has become accustomed to experimental and developmental pavement structures since 2009. This bears testament to SANRAL’s and the road construction industries’ everlasting quest to enhance the quality of roads in South Africa through innovative pavement solutions.
This article will aim to provide an update of the short term performance of the 2015 SANRAL project in which Royal Haskoning DHV (Consultant) and Martin and East (Contractor) successfully constructed a 120mm EME Asphalt Base, as well as 70mm and 100mm Ultra Thin Continuously Re-inforced Concrete (UTCRC) pavements along one of the most heavily trafficked routes in South Africa.
Photo 1: EME along the Crawler Lane (Outer LHS Lane only)
Project Location and Specifications
The special maintenance of the truck crawler lane on National Route 1 Section 1 comprised of four different pavement design strategies, with details as summarized in Photo 2 and Table 1:
UPDATE ON THE SHORT-TERM PERFORMANCE OF ENROBÉ À ÉLEVÉ (EME) ON THE N1
Photo 2: Schematic Showing the Location of the Different Pavement Strategies
Authored by: Imraan Amien & Bernhard Botes (Royal HaskoningDHV); Dirk Immelman (Western Cape Government)
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Pavement Startegy Start Chainage
End Chainage
Production Rate
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Continuously Reinforced Concrete Pavement (CRCP)
160mm / 190mm
km 61.0 km 60.4 85 m/day 600 m
EME Asphalt Base
120mm + 20mm UTFCkm 59.6 km 57.4 170 m/day 2520 m
Ultra-Thin Continuously Reinforced Concrete Pavement (UTCRCP) 70 mm km 57.4 km 56.9 35 m/day 500 m
Ultra-Thin Continuously Reinforced Concrete Pavement (UTCRCP) 100 mm km 56.9 km 56.4 30 m/day 500 m
Table 1: Summary of different Pavement strategies along the Truck Crawler Lane on the National Route 1 Section 1
Construction of the EME Asphalt Base Layer
A total of 3100 tons of EME was placed in 2 x 60 mm layer lifts to yield a final base layer thickness of 120 mm. Due to the uncertainty surrounding the product at the time, the contractor sensibly opted to place the EME at a conservative rate of 240 tons per day. However, despite these precautionary measures, the production rates of the EME remained far superior to all other pavement strategies in the project (see Table 1 above).
Prior to construction, the general industry consensus around EME at the time of the project was that there existed a very small compaction window in which the desired compaction densities could be achieved before the asphalt mat “locked up” due to the stiffness of the 10/20 binder. This initial fear was compounded further by the relatively long haul distances between the asphalt plant and the site. In order to allow for sufficient time to compact the mix before this supposed “phenomenon” occurred, it was decided to mix the asphalt at temperatures in excess of 180 °C during the construction of the trial section; despite industry best practices calling for asphalt to be mixed at temperatures between 160 °C and 180 °C (Sabita, 2013). Unfortunately as a result of these elevated mix temperatures, the mat behaved tenderly during compaction, even after cooling. This presented difficulty in compacting the mix, ironically in an opposite fashion to what was initially expected from the EME’s supposed “locking up” potential.
Subsequently, it was decided to reduce the mixing temperature to within industry norms (170 °C) for the remainder of the project. Thereafter, the mix began to behave like a typical asphalt mix as the required compaction densities were easily achieved and no “locking up” of the asphalt was experienced.
Performance of the EME to date
A visual assessment was conducted in June 2017 (18 months after construction) to evaluate the current in-service performance of the EME.
The site conditions in which the EME was constructed may be considered as extreme - due to the combination of steep grades, high ambient temperatures and slow moving heavy vehicles it is subjected to. However, during the visual assessment, the only observable defect recorded was bleeding at minor isolated sections along the left-sided wheel path. This defect was confined to the UTFC and did not originate in the EME. Minor mechanical deformation was also observed at isolated sections along the UTFC; however this was not related to the performance of the EME.
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Photo 3: Isolated Bleeding Spots on the EME
In closing…
This section of road will be continuously monitored over the coming years to assess the long term performance of the EME technology in South Africa. Exciting times lay ahead for the future of this technology and we trust that the lessons learnt and knowledge gained from this unique project will help “pave” the way forward in creating a sustainable, lasting and safe road network in South Africa.
“Trucks will come and go through the Huguenot Tunnel but EME is here to stay for the long haul”
NATIONAL INTERNATIONALSabita BitSafe Train-the-Trainer
10-12 October, 2017 - Cape Town
2nd Iran Bitumen/Asphalt Forum
5-6 September, 2017 – Tehran, Iran
Material Tester Course; Module 6 – Asphalt
24-27 October, 2017 - Durban
IICTG Conference
26-28 September, 2017 – Minnesota, USA
34th Road Pavement Forum
14-15 November, 2017 - CSIR, Pretoria
Pavement Preservation & Recycling Summit
26-28 March, 2018 – Nice, France
SARF/IRF/PIARC Regional Conf. for Africa
9-11 October, 2018 – ICC, Durban
Rubberized Asphalt Rubber Conference
25-28 September, 2018 – Kruger Park, Skukuza
EVENTS
33
HONOURING THOSE THAT LEAVE A HERITAGEIndustry in general and SANRAL in particular has been blessed to have gained the insight and wisdom that Dennis Rossmann has utilized and shared in his working career, largely in his capacity in the Pavement and Materials Engineering field. To mark his formal retirement at the end of June 2017 a vote of thanks on behalf of industry was conveyed at the May Road Pavement Forum by Sasheen Rajkumar who conveyed messages from several colleagues – within and beyond SANRAL, some of whom have known Dennis for 40 years!These are just some of the statements made about this Pad-Maker:
• In your own way you have contributed massively to improving the quality of road construction in South Africa.
• Your dedication, knowledge, honesty and integrity shine on all those that you have interacted with.
• SANRAL is losing its V12 Engine, we are losing our very own Einstein on the Pavements and Materials division.
• Dennis has made a large contribution to all the working committees that he led and was responsible for. He played a main roll in all the materials related manuals, standards, specifications, test methods, and author and co-author of many national and international papers.
• We have in our industry the starters, the doers and the finishers, the leaders and managers – but seldom will you find a man who fits everywhere, adding structure and colour to the entire picture of road engineering with discipline and wit.
On 13th July, Sabita Council Chairman, Mr Mike Winfield presented Dennis with Honorary Membership in recognition of the past value that has been afforded to industry that will be taken into the future. Dennis is thanked for all that he has done and although now ‘retired’ all that is he going to do.
We would like to take this opportunity to also acknowledge Sabita’s other long-standing Honorary Members, who through their dedication to industry and the pertinent role that they played in leading Sabita have been awarded this category of membership over the years.
1992 - Mr W.G. Babb Elected onto Council in 1982, representing the then Transvaal region and in 1987 was elected Chairman of Council.
1992 - Mr D.G. Green Signatory to the foundation meeting in 1979, Mr Green served as Treasurer, & over time, Chairman of the Finance, Education and Technical committees.
1992 - Mr J.A.M. Pike Max Pike served as Councillor, represented the Cape Regional Committee and served as Chairman of the Planning and Finance Committee.
1995 - Mr R.H. Kingdon Mr Kingdon was the first Executive Director and actively involved in the formation of Sabita and contributed to its first constitution.
1997 - Mr D.L. Orton As Chairman, his inspired and visionary leadership enabled Sabita to come to grips with exciting challenges presented during 1987 to 1992.
2006 - Mr P A Myburgh Piet Myburgh’s service to Sabita has spanned 36 years! Although he retired as CEO in 2006, Piet has remained actively involved ever since.
2006 - Mr D.J. Stiglingh He is remembered for his fair, objective leadership and his influence in Introducing principles of sound corporate governance.
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Sabita has recently issued an HSE Communication Notice regarding the control of silica dust exposure on asphalt pavement milling machines which is under discussion and once finalised will be forwarded to industry. Pertinent information extracted from the notice is summarised as follows:
The Facts about Silica Exposure
Many thousands of South African workers are exposed to respirable crystalline silica that exceed current occupational exposure limits. Inhaling respirable crystalline silica can cause silicosis, a debilitating and potentially fatal lung disease as well as obstructive pulmonary and renal disease. Milling and cutting can create airborne dust containing silica, however, dust controls such as ventilation controls used in combination with water-spray controls on asphalt pavement milling machines can consistently reduce exposures below the South African control limit.
Occupational Health and Safety Act
Employers have legal duties and obligations in accordance to the Act (No. 85 of 1993 as amended). Section 8 states: “Every employer shall provide and maintain, as far as is reasonably practicable, a working environment that is safe and without risk to the health of his employees.” In particular, reference is made to the Hazardous Chemicals Substance Regulations – and to ensure that arrangements are in place to assure full compliance. The minimum expectation regarding assessment of potential exposure is to determine if and to what extent operators and other workers involved in Asphalt Milling are exposed. This baseline assessment should then be used to make decisions on what further action is required to fully comply with the Regulations in order to protect employees against excessive exposure.
What you can do to reduce Silica Dust Exposure in Asphalt Pavement Milling
• Use ventilation and water-spray controlso Ventilation controls used in conjunction with water-spray controls can consistently reduce
exposures below the OEL-CL;o Typical ventilation controls designed to reduce silica exposure on asphalt pavement
milling machines include a collection hood, fan, and ductwork.o Milling machines should also be designed to allow the operator to temporarily turn the
ventilation control off when milling into the wind.o Water-spray controls should always remain on regardless of wind direction.
• Always use water-spray controls on asphalt pavement milling machines that do not have ventilation controls
o When ventilation controls are unavailable, water-spray systems that are properly designed, operated, and maintained can provide a significant reduction in the milling machine’s dust generation.
• The machine operator’s manual should contain a maintenance schedule for the water-spray or ventilation controls. This manual should include detailed sketches, performance criteria, and trouble-shooting instructions for equipment owners to use in their periodic inspection of the controls.
For more information on the design of controls and the methods used to test them, refer to the NIOSH document “Best Practice Engineering Control Guidelines to Control Worker Exposure to Respirable Crystalline Silica during Asphalt Pavement Milling.” www.cdc.gov/niosh/docs/2015-105 .
CONTROLLING SILICA DUST EXPOSURE
Health & Safety
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SABI
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DS Manual 1 Technical guidelines: Construction of bitumen rubber seals 3rd edition, 1998
Manual 2 Bituminous binders for road construction and maintenance (CD) 6th edition, 2014
Manual 3 (Withdrawn)
Manual 4 (Withdrawn)
Manual 5 Guidelines for the manufacture and construction of hot mix asphalt 3rd edition, 2008
Manual 6 (Withdrawn)
Manual 7 SuperSurf – Economic warrants for surfacing roads 1st edition, 2005
Manual 8 Guidelines for the safe and responsible handling of bituminous products (CD) 3rd edition, 2011
Manual 9 (Withdrawn)
Manual 10 Bituminous surfacings for low volume roads and temporary deviations (CD) 2nd edition, 2012
Manual 11 (Withdrawn) 1st edition, 1993
Manual 12 Labour Absorptive methods in road construction using bituminous materials (CD) 4th edition, 2016
Manual 13 LAMBs – The design and use of large aggregate mixes for bases 2nd edition, 1997
Manual 14 (Superseded by TG2)
Manual 15 (Withdrawn)
Manual 16 (Withdrawn)
Manual 17 Porous asphalt mixes: Design and use (CD) 1st edition, 1995
Manual 18 Appropriate standards for the use of sand asphalt 1st edition, 1996
Manual 19 Guidelines for the design, manufacture and construction of bitumen rubber asphalt wearing courses (CD)
4th edition, 2016
Manual 20 Sealing of active cracks in road pavements 1st edition, 1998
Manual 21 (Superseded by TG2)
Manual 22 Hot mix paving in adverse weather 2nd edition, 2006
Manual 23 Code of practice: Loading bitumen at refineries (CD) 2nd edition, 2011
Manual 24 (Withdrawn) 1st edition, 2005
Manual 25 Code of practice: Transportation, off-loading and storage of bitumen and bituminous products (CD)
2nd edition, 2012
Manual 26 Interim guidelines for primes and stone pre-coating fluids (CD) 2nd edition, 2011
Manual 27 Guidelines for thin hot mix asphalt wearing courses on residential streets 1st edition, 2008
Manual 28 Best practice for the design and construction of slurry seals (CD) 1st edition, 2010
Manual 29 Guide to the safe use of solvents in a bituminous products laboratory (CD) 1st edition, 2010
Manual 30 A guide to the selection of bituminous binders for road construction (CD) 1st edition, 2011
Manual 31 Guidelines for calibrating a binder distributor to ensure satisfactory performance (CD) 1st edition, 2011
Manual 32 Best practice guideline and specification for warm mix asphalt (CD) 1st edition, 2011
Manual 33 Design procedure for high modulus asphalt (EME) (CD) 2nd edition, 2015
Manual 34 (A) Guidelines to the transportation of bitumen and (B) Bitumen spill protocol (CD and Booklets)
1st edition, 2013
Manual 35/TRH8
Design and use of Asphalt in Road Pavements (Pdf – complimentary) 1st edition, 2016
Technical guidelines
TG1 The use of modified binders in road construction 3rd edition, 2015
TG2 Bitumen stabilised materials (UNDER REVIEW) 2nd edition, 2009
TG3 Asphalt reinforcement for road condition 1st edition, 2008
DVDs
DVD100 Test methods for bituminous products
DVD200 Training guide for the construction and repair of bituminous surfacings by hand
DVD300 Manufacture, paving and compaction of hot mix asphalt
DVD410 The safe handling of bitumen
DVD420 Treatment of bitumen burns
DVD430 Working safely with bitumen
DVD440 Firefighting in the bituminous products industry
DVD450 Safe loading and off-loading of bitumen
SABITA MANUALS AND DVDS
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SABITA BOARD MEMBERS
PRODUCER MEMBERS
Colas SA (Pty) LtdP.O. Box 82, Eppindust, 7475Tel: 021 531 6406 | Fax: 021 531 5514
Much Asphalt (Pty) LtdP.O. Box 49, Eerste Rivier, 7100Tel: 021 900 4400 | Fax: 021 900 4446
National Asphalt (Pty) LtdP.O. Box 1657, Hillcrest, 3650Tel: 031 736 2146 | Fax: 031 736 1938
Shell Downstream SA (Pty) Ltd6 Ipivi Road, Kloof, 3610Tel: 031 571 1000 | Fax: 031 764 6208
Rand Roads (a div. of Aveng Grinaker LTA)Private Bag X030, Kempton Park, 1620Tel: 011 923 5000 | Fax: 086 721 8513
Tosas (Pty) LtdP.O. Box 14159, Wadeville, 1422Tel: 011 323 2000 | Fax: 086 765 0890
Zebra Surfacing (a div. of Martin & East (Pty) Ltd)P.O. Box 14335, Kenwyn, 7790Tel: 021 761 3474 | Fax: 021 797 1151
Total SA (Pty) LtdP.O. Box 579, Saxonwold, 2132Tel: 011 778 2000 | Fax: 086 680 3283
SABITA MEMBERS
We welcome CIM Chemicals who joined Sabita as an Associate member in May 2017. CIM is much more than just a chemicals, flavours, fragrances and food distribution company.
Operating nation-wide, with procurement from both local and international suppliers, they offer an array of quality products to fit companies’ detergent, pharmaceutical, food and metallurgical needs, at competitive prices. Their promise of national delivery ensures that no matter where in South Africa a company is based, they will go above and beyond to meet individual requirements.
The Aggregate and Sand Producers Association of Southern Africa (ASPASA) based in Randpark Ridge in Gauteng is a voluntary membership, private sector producers association that
Sabita has recently entered into reciprocal membership with. Aspasa is a member of the Chamber of Mines, but represents those companies that are in the business of producing aggregate and sand and is better known for operating quarries, sand pits and crushing operations. Aspasa stands on its own, even though a member of the Chamber.
The support that Aspasa gives its members is on the strategic and advisory sides of business. A great deal of work is put into promoting the industry and the association to the outside world, but also to ensure interaction among other companies/producers in the industry.
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ORDINARY MEMBERS
Actophambili Roads (Pty) Ltd P O Box 16661 Atlasville 1465 Tel 011 3952293
AmandlaGCF Construction cc P O Box 6064 Welgemoed 7538 Tel 021 9817070
AJ Broom Road Products cc P O Box 16421 Dowerglen 1612 Tel 011 4543102
Aqua Transport & Plant Hire (Pty) Ltd Private Bag X11 Ashwood 3605 Tel 031 5336883
Astec – Asphalt Technology P O Box 589 Rothdene 1964 Tel 016 3621310
Bituguard Southern Africa P O Box 2523 Bethlehem 9700 Tel 058 3037272
Bitumen Supplies & Services (Pty) Ltd P O Box 1028 Sunninghill 2157 Tel 011 8039338
Bitumen World PVT P O Box AY20 Amby Harare Zimbabwe Tel +263 772417102
Cruze (Pty) Ltd P O Box 742 Gallo Manor 2052 Tel 011 0500705
Emergeco Trading (Pty) Ltd P O Box 635 Umhlanga Rocks 4320 Tel 031 4812450
Javseal (Pty) Ltd P O Box 26317 Isipingo Beach 4115 Tel 031 9025988
Milling Techniks (Pty) Ltd P O Box 779 Gillits 3603 Tel 031 7929580
More Asphalt (Pty) Ltd P O Box 2180 Durbanville 7550 Tel 021 9750784
Murray & Roberts Infrastructure P O Box 585 Bedfordview 2008 Tel 011 5905843
Nolans Earthworks & Plant cc P O Box 28617 Haymarket 3200 Tel 033 3866455
Polokwane Surfacing (Pty) Ltd P O Box 288 Ladanna 0704 Tel 015 2931221
Power Construction (Pty) Ltd P O Box 129 Blackheath 7581 Tel 021 9071300
Puma Energy Services SA (Pty) Ltd Postnet Suite 190 Private Bag X31 Saxonwold 2132 Tel 011 3436998
Raubex (Pty) Ltd P O Box 3722 Bloemfontein 9300 Tel 051 406 2000
Raubex KZN (Pty) Ltd P O Box 10302 Ashwood 3605 Tel 031 7006411
Road Material Stabilisers P O Box 84513 Greenside 2034 Tel 011 3903499
Spray Pave (Pty) Ltd P O Box 674 Alberton 1450 Tel 0118685451
Tau Pele Construction P O Box 13125 Noordstad 9302 Tel 0514360103
ASSOCIATE MEMBERS
Advanced Polymers (Pty) Ltd P O Box 9452 Edenglen 1613 Tel 011 3977979
AECOM SA (Pty) Ltd P O Box 3173 Pretoria 0001 Tel 012 4213500
Afrisam SA (Pty) Ltd P O Box 6367 Weltevreden Park 1715 Tel 011 6705500
Ammann Const. Machinery SA (Pty) Ltd Private Bag X43 Rynfield 1500 Tel 011 8493939
Anton Paar Southern Africa P O Box 50471 Randjiesfontein 1683 Tel 011 0215165
Aurecon SA (Pty) Ltd P O Box 494 Cape Town 8000 Tel 021 5269400
BSM Laboratories (Pty) Ltd P O Box 15318 Westmead 3608 Tel 031 7646537
BVi Consulting Eng. W Cape (Pty) Ltd P O Box 86 Century City 7446 Tel 021 5277000
CIM Chemicals (Pty) Ltd Pnet Suite 479 PBag X 29 Gallo Manor 2052 Tel 011 7081494
Dick King Lab Supplies (Pty) Ltd P O Box 82138 Southdale 2135 Tel 011 4999400
DuPont de Nemours SA (Pty) Ltd P O Box 3332 Halfway House 1635 Tel 011 2188600
EFG Engineers (Pty) Ltd P O Box 3800 Durbanville 7551 Tel 021 9753880
Gibb (Pty) Ltd P O Box 3965 Cape Town 8000 Tel 021 4699172
Glad Africa Consulting Eng. (Pty) Ltd P O Box 3893 Cape Town 8000 Tel 021 4626047
GMH/Tswelo Consulting Engineers P O Box 2201 Randburg 2125 Tel 011 4620601
Hatch Goba (Pty) Ltd P O Box 180 Sunninghill 2157 Tel 011 2363331
HHO Africa P O Box 6503 Roggebaai 8012 Fax 021 4252870
Impact Chemicals (Pty) Ltd P O Box 30792 Kyalami 1684 Cell 082 8998187
iX Engineers (Pty) Ltd P O Box 22 Menlyn 0063 Tel 012 7452000
JG Afrika (Pty) Ltd P O Box 1109 Sunninghill 2157 Tel 011 8070660
Kantey & Templer (Pty) Ltd P O Box 3132 Cape Town 8000 Tel 021 4059600
MEM
BERS
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MEM
BERS
ASSOCIATE MEMBERS (continued)
Kaymac (Pty) Ltd T/A Kaytech P O Box 116 Pinetown 3600 Tel 031 7172300
Lafarge Industries SA (Pty) Ltd Private Bag X26 Gallo Manor 2052 Tel 011 6571156
Leo Consulting (Pty) Ltd P O Box 32798 Totiusdal 0135 Tel 087 9805004
Mott MacDonald Africa (Pty) Ltd P O Box 7786 Roggebaai 8012 Tel 021 4405060
Nadeson Consulting Services (Pty) Ltd P O Box 51121 V&A Waterfront 8002 Tel 021 4184988
Naidu Consulting (Pty) Ltd P O Box 2796 Westway 3635 Tel 031 2656007
NAKO Iliso P O Box 686 Gillits 3603 Tel 031 2662600
Namibia Technical Services cc P O Box 30623 Windhoek Namibia Tel +264 61 215324
Rankin Engineering Consultants P O Box 50566 Lusaka Zambia Tel +260 1 290562
Royal HaskoningDHV P O Box 867 Gallo Manor 2146 Tel 011 7986051 Sasol Chemicals a div. of Sasol SA (Pty) Ltd Chemcity 2 P O Box 1 Sasolburg 1947 Tel 016 9602126
SMEC SA (Pty) Ltd P O Box 72927 Lynnwood Ridge 0040 Tel 012 4813821
Specialised Road Tech. (Pty) Ltd P O Box 15324 Westmead 3608 Tel 031 7004510
TPA Consulting (Pty) Ltd P O Box 1575 Westville 3630 Tel 031 7651907
Tshepega Engineering (Pty) Ltd P O Box 33783 Glenstantia 0010 Tel 012 6652722
Worldwide Tanks on Hire cc P O Box 2250 Durban 4000 Tel 031 3620207
WSP Group Africa (Pty) Ltd P O Box 98867 Sloane Park 2152 Tel 011 3611402
Zimile Consulting Engineers P/ Suite 252 Private Bag X11 Halfway House 1685 Tel 011 4668576
AFFILIATE MEMBERS
Cape Pen. Univ. of Technology P O Box 652 Cape Town 8000 Tel 021 4603074
DMV Harrismith (Pty) Ltd P O Box 912 Harrismith 9880 Tel 058 6222676
Durban University of Technology P O Box 101112 Pietermaritzburg 3209 Tel 033 8458916
Gavin R.Brown & Associates P O Box 51113 Musgrave 4062 Tel 031 2025703
GT Design & Technologies 137 Jan Hofmeyr Road Westville 3630 Tel 031 2660933
IMESA P O Box 2190 Westville 3630 Tel 031 2663263
Instant Tar Services P O Box 17219 Norkem Park 1631 Tel 011 3935194
Letaba Laboratory (Pty) Ltd P O Box 739 White River 1240 Tel 013 7527663
Mdubane Energy Services (Pty) Ltd 214 9th Ave. Morningside Durban 4001 Tel 031 3042470
Mmila Civils & Traffic Services P O Box 40158 Faerie Glen 0043 Tel 012 9933098
Nathoo Mbenyane Engineers P O Box 47595 Greyville 4023 Tel 031 3122097
Nelson Mandela Metro. University P O Box 77000 Port Elizabeth 6031 Tel 041 5043298
N3TC (Pty) Ltd P O Box 2063 Bedfordview 2008 Tel 011 4543596
Outeniqua Laboratory (Pty) Ltd P O Box 3186 George Industria 6536 Tel 044 8743274
Pride Lab Equipment (Pty) Ltd 3 Van Eyck Crescent De La Haye Bellville 7530 Tel 021 9462018
Reliance Laboratory Equipment P O Box 911-489 Rosslyn 0200 Tel 012 5498910
Salphalt (Pty) Ltd P O Box 234 Isando 1600 Tel 011 8232218
South African Road Federation P O Box 8379 Birchleigh 1621 Tel 011 3945634
Unique Trading and Outsourcing P O Box 5424 Benoni South 1502 Tel 011 7403452
Uni. of Pretoria Dept. Civil Eng. Lynnwood Road Hatfield 0002 Tel 012 4202171
Uni. of Stellenbosch Dept. Civil Eng. Private Bag X1 Matieland 7600 Tel 021 8084379
FOREIGN MEMBERS
Raetex Industries 550 Tiburon Blvd Suite B-1 TiburonCA 94920 United States of America Cell 072 0315266
Rettenmaier & Söhne GMBH Global (establishing a base in Johannesburg) Tel 011 5348619
Kraton Polymers Netherlands B.V Transistorstraat 16 NL-1322 CE Almere, The Netherlands Cell 082 4570210
LIESEN Bitumen (Pty) Ltd 107 Hope Street Cape Town 8001 Tel 021 3001631
Zydex Industries Gujaret India T+91 2653312000
Asphalt News is published by the Southern African Bitumen Asso-ciation (Sabita),a non-profit organisation sponsored by its mem-bers to serve all stakeholders through engineering, service and education.
Sabita and the associations listed below have founded a global strategic alliance of asphalt pavement associations (GAPA) and are working jointly towards a full, open and productive partnership:
Australian Asphalt Pavement Association (AAPA)European Asphalt Pavement Association (EAPA)Japanese Road Contractors Association (JRCA)Mexican Asphalt Association (AMAAC)National Asphalt Pavement Association (NAPA)Civil Contractors New Zealand
The contents of this publication may be reproduced without any changes and free of charge, providing the source is acknowledged.
Southern African Bitumen Association (Sabita)Postnet Suite 56, Private Bag X21 | Howard Place, 7450, South AfricaTel: +27 21 531 2718 | Fax: +27 21 531 2606 | Email: [email protected]
WWW.SABITA.CO.ZA
