Steph Bredenhann summed up the Winter Seal Workshop held by SAT in April 2014 with some thoughts on the current scenario at the time and the way forward. For him the important steps in the success of winter seal applications include sharing of knowledge, planning, and attention to detail, bearing in mind that this is not an exact science. He also maps out a brief strategy for the future.
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Moisture is the greatest enemy of any asphalt layer. This presentation talks to the paradigm shift that is needed in design thinking and budgeting to avoid moisture ingress, supported by relevant case studies.
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Binder modification has become the norm as the performance limits of conventional bitumen have been reached. The author believes practitioners need to understand all modifiers to provide the best match for each application. This presentation provides an overview of different modifiers available and how to use them to overcome different binder limitations.
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Kim Jenkins talks us through the key factors, including various test results that help practitioners to make informed decisions. The presentation touches on bitumen specifications and performance grading, BBS tests including adhesion/cohesion factors, hot applied binders versus emulsions, the influence of precoat, manufacturing temperature and more. Well informed decisions can be made when selecting materials for surface seals if BBS properties are known, Jenkins concludes.
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How to design a mix using RA – this paper has it all. Learn about mix selection from types to design considerations, getting the proportioning of new aggregate, new binder and RA right, tests to be conducted on RA samples, and the use of rejuvenators. Wynand Nortje closes off with advice on testing of the recycled asphalt mix.
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Herman Marais introduces emerging technologies in bitumen modification including polymer modification (PMB), crumb rubber, micro filler and nanotechnologies. He concludes that PMB is the most popular modifier with exciting future prospects, crumb rubber use is expected to increase as storage stability risks are reduced and new blends are developed, micro filler shows promise, and nanotechnologies will become less expensive with increased production.
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Nico shares Roadlab’s expertise in this field, starting with tests currently used to determine material properties before treatment/stabilization/modification, followed by the properties of Nano Modified Emulsion (NME) treated materials together with testing technologies and procedures.
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For those who need a deeper understanding, it is all included in this detailed summary – versatility, water resistance, ductility, cohesion, adhesion, elastic recovery, softening point, penetration, temperature susceptibility, viscosity, oxidation, specific gravity and durability.
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Ensure that the project mix materialises on site by sticking to some basic principles. This presentation enlarges on the basics such as quality control of mixes containing reclaimed asphalt (RA), consistency of RA fractions in the mix, aspects to consider at stockpiles, moisture content, and finally sampling, testing and acceptance control as for conventional asphalt mixes.
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Greg Reynolds details all the steps from milling and stockpiling to processing and optimal use of reclaimed asphalt.
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Why the problems? What has changed? These are the questions Dennis asks and answers. Professional project management and quality engineering are essential to achieving the fundamentals of optimized compaction and limited saturation. A detailed account of what is good and what’s not. By Dennis Tossmann (SANRAL).
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What does “nano-technology” mean? What are the problems we need to solve in a South African context? Prof Jordaan takes us from the basics of road pavement engineering and the mind shift required to move from conservative and expensive methodologies to exploring “new-age” nanotechnologies. This detailed presentation covers everything from current material design practices to recommendations for efficient and cost effective alternatives, together with project examples.
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What are polymer modified bitumen and rubber modified binder? What do we achieve by modifying base bitumen? Get the answers and the detail on types of polymer modifiers, blending plants, production and mixing processes. Construction company Tau Pele shares its practical experience on what to expect and pitfalls to avoid. The presentation ends with a brief look to the future.
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This presentation explains what you need to know about base course problems and how to avoid the pitfalls. Get a grip on whether its base course factors contributing to asphalt failure, or asphalt design aspects contributing to base course related failure. By Eben van Zyl.
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A brief overview of this exciting new technology that is capable of modifying feedstock bitumen to produce multigrade bitumen, how it works and the results it achieves. What is multigrade bitumen and why is it so important to the industry? As with all new technology, there are also key learning points and future plans to be shared.
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Ensure that the project mix materialises on site by sticking to some basic principles. This presentation enlarges on the basics such as quality control of mixes containing reclaimed asphalt (RA), consistency of RA fractions in the mix, aspects to consider at stockpiles, moisture content, and finally sampling, testing and acceptance control as for conventional asphalt mixes.
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A binder manufacturer discusses the impact of historic seasonal trends on availability of products and services, the characteristics of winter seal products, and issues around health, safety and the environment.
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Herman Marais provides a definition and discusses nanotechnologies in use and under development, as well as future opportunities. Of particular interest is the South African experience of nanotechnologies, including examples of studies conducted to date.
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Georges Mturi points out that about 30% of bitumen used in asphalt in South Africa is modified. In this paper he discusses the context, typical additives used, guidelines and specifications, as well as selection and classification of additives.
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Caroline Marais looks at the critical issues of quality control including heating of modified binders, tank management and handling; transportation hazards to watch out for; and HSE covering the effects of H2S exposure, prevention of emissions, bitumen safety, essential PPE and more.
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Dr Horak’s presentation explains the Bailey Method (BM) basis of packing analysis, the Dominant Aggregate Size Range (DASR) method and Binary Aggregate Packing (BAP) principles, and the integration of the three methods to improve aggregate packing efficiency in asphalt mix designs.
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All you need to know including current practices, international and South African trends and experience, embargos, different binders, feedback on stripping and cutters, and evaluation of both trial and existing winter seals.
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Reclaimed asphalt (RA) is the industry’s answer to environmental sustainability. Here you will gain an understanding of the use of RA from removal to stockpiling of unprocessed RA and avoiding moisture ingress, to crushing, screening and fractioning, stockpiling processed RA, and finally optimising its use.
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If nanotechnology is new to you, this is a great A to Z explanation. You will get the background, definitions, FAQs, history, science and mythbusters. Application of nanotechnology can lead to advances in solving general road engineering problems…
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Aggregate properties need to be clearly defined in terms of both specification and testing to ensure compliance. To support this, Ray Bonser reviews the relevant specifications including historic factors, the introduction of COLTO 1998, the Aspasa Exclusion Clauses, the current SANS 1083:2018 Edition 2.6 specification and proposed revisions to SANS 1083.
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Dennis Rossmann drives home the importance of an advance QA plan to agree responsibilities and verify sampling procedures. He goes on to list tests envisaged for all sealing and the differences to be aware of for winter sealing.
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This presentation will give you the lowdown on methods for storing aggregate, techniques for moving aggregate, sampling techniques, moisture issues, and quality. The objective is to ensure consistency of material, minimising both moisture content and contamination.
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Johannes Lambert covers all the bases in this detailed presentation, including the chemistry and refining of bitumen, classification and properties of bitumen binders…
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Since void content has a direct bearing on asphalt performance, the reliability of void content determination methods is key. Tafadzwa Mafuma looks at findings by the CSIR and Much Asphalt to provide feedback on different methodologies.
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Premature failure is a manmade phenomenon. For surfacing to perform properly, the G1 base needs to provide a well-knit aggregate mosaic. Kleyn works on the principle that mosaic particle interlock (density) = stability/strength…
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The pros and cons of both standard and “new age” field and laboratory permeability testing methods. The author warns that an accurate void determination method is critical to high levels of correlation, no matter which tests you choose. By Joanne Muller.
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Sound HSE practices are essential in the handling of bitumen and bituminous products and this presentation gives us a good overview. Learn about safe and responsible handling of bitumen, hazards to watch for, procedures to follow, how to plan for transportation and storage, and how to carry out drum decanting successfully. Not forgetting quality control, you will also get the basics of the all-important sampling and testing procedures.
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The A to Z of sealing, starting with the history of specifications developed in SA and proposed changes. The presentation continues with aggregate and bituminous binder specs for seals; plant and equipment required; methodology; construction considerations such as early trafficking, aggregate spread rate and road surface temperature; and finally contractual issues on when to include a winter seal option and payment items for winter sealing.
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Find out how an understanding of the complex geological aspects of aggregates can help you meet the required specifications. Robert Leyland breaks the discussion down into rocks and minerals and the geology of South Africa. Then there are the specifications where geological aspects such as durability, strength, shape, water absorption and bitumen affinity of rock types all make a difference. This paper gets to the heart of the subject.
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A step-by-step methodology using existing statistical concepts as a screening and analysis tool to determine asphalt permeability. This paper shows how you can let the data itself lead you to the answers by using simple statistical analysis tools. Report on trends and results such as deterioration, Weak spots and quality control in a visual manner that is easily understood. By Ané Cromhout.
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There are various mixing plants with different capabilities that can be used for asphalt mixes incorporating RA, as well as recycling batch plants. Herman Marais provides the information you will need. While the same basic types of mixing plants are used, modifications are required, and standard plants should not be used to produce asphalt with high RA content.
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To optimize aggregate unit cost and quality, it is essential for quarries to adopt a systems based approach that considers all the independent variables influencing aggregate production, asserts Dr Basson. His paper covers the constraints and goals of every aspect of the process: drill and blast design, load and haul, crushing principals and crusher selection, and the screening process.
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Johan provides a detailed account, with focus on priming, tacking, selection of the right bonding agents, product comparisons and relevant r&d, quality assurance, and how to identify surfacing problems along the way.
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Sasheen Rajkumar provides a global and local view, starting with a definition of RA and the historic context. He goes on to detail the asphalt recycling process, mix types, influencing factors, and issues around quality. What are the environmental and economic benefits and, importantly, the regulations around ownership and disposal of RA?
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Jacques van Heerden takes us through all the background we need to know about bitumen. Starting with the history of bitumen including ancient uses and deposits, he brings us up to date with the sources, properties, composition and chemistry of crude oil, as well as an overview of crude oil exploration and refining. The presentation concludes with a synopsis of bitumen production in SA and the differences between bitumen and tar.
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In this second presentation of the series, Jacques van Heerden continues with a definition of bitumen and explains classifications of bituminous binders and traditional bitumen testing. The meaning of rheology is clarified, and our understanding of bitumen improves with details of its chemistry, ageing and bitumen blowing. Readers will also discover that bitumen is a versatile product with many uses outside the asphalt industry.
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This presentation covers the essentials of binder testing in winter seals, with focus on the properties of cutback binders used in cold temperatures in South Africa, the rheological effects of adding paraffin, site testing including getting cutter quantities right, gas chromatography and mass loss. Also get the lowdown from Johan O’Connell on evaluating the curing rate of winter seals.
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Find out what lessons can be learned from sealwork trials – from seal geometry to binder aggregate contact and adhesion, to temperature and micro-climates, to cutters, precoating and bond strength, base preparation and viscosity. Gerrie provides practical recommendations for asphalt practitioners.
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Group Five Civil Engineering participated in winter seal trials on the N14 Section 7 between Kathu and Kuruman in the Northern Cape Province and Section 8 between Kuruman and the North West Province border. Thomas Moolman shares the trial specifications as well as observations on the outcomes. He concludes that winter seal construction can be used in South Africa to ensure a continuous flow of road and road rehabilitation projects and reduce/spread the demand on the manufacture and supply of bitumen and surfacing aggregates.
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