Asphalt Review - Volume 29 Number 2 (June / July 2010)

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ASPHALT REVIEW southern hemisphere; CIAL supports any innovation that reduces the carbon footprint on a sustainable basis. CIAL has a rolling 20-year APMW program which makes it possible to look at paving opportunities that take advantage of these opportunities to trial several innovations. One of the innovations submitted to CIAL for approval was the trial CoolPave, on the airfield. Not only are there significant energy fuel savings, it is a much safer product to manage and compact. A trial section of CoolPave was laid on Taxiway A. Fulton Hogan laid 141 tonne (598m2) to a depth of 110mm on Taxiway A during February 2008. Subsequent testing and inspections of the CoolPave trial showed that CoolPave was as stable and as strong as the standard hot mix product used normally on the airfield. This first trial gave CIAL enough confidence to use CoolPave on a larger scale trial overlay on Taxiway F in February 2009. For this trial, 515 tonne (2,745m2) was laid. The full scale trial on Taxiway F is performing as designed. Testing and inspection are consistent with the small trial on Taxiway A. Handling the CoolPave was easier and much safer for the paving team than the standard hot mix product with no blue smoke and much lower temperatures. A smaller trial of 38 tonne using CoolPave with 30% Recycled Asphalt Pavement (RAP) was also completed on Taxiway F. The use of RAP reduces the amount of virgin binder required resulting in less cost and less fuel being used. The results of this trial are being assessed. CIAL is about to enter into a 5 year agreement with both Fulton Hogan and BECA to maximise the value of collaborating to reduce total cost of ownership in the delivery of APMW at CIAL. Part of this process is excelling at sustainable innovation for the benefit of all parties involved. CIAL is thrilled with the results from these trials. The trials pave the way for using CoolPave across more taxiway areas and possible trials on runway areas. CIAL will continue to work with Fulton Hogan on sustainable innovations within the APMW and any others areas within the Airport campus. 7. Conclusions Recent advances have provided methods for the production of hot-mix asphalts at lower temperatures. These new production techniques have been termed “warm-mix asphalts” and more recent developments that further lower production and placement temperatures, “half-warm asphalts”. Fulton Hogan has implemented a “half-warm asphalt” technology under the CoolPave brand. Substantial tonnages of CoolPave-type half-warm asphalt pavements have been constructed in Europe and the United States. All evidence suggests that the CoolPave asphalt is at least as good as conventional hot-mix asphalt, if not better. Trials in New Zealand support these findings. There appear to be no technical barriers to the implementation of the CoolPave “half-warm” asphalt in New Zealand. There are economic constraints; plant upgrade and chemical costs are not insignificant. However, as fuel costs continue to rise, the economic barriers will disappear. It can sometimes be difficult to demonstrate the benefits of new technologies to clients. CoolPave is an exception to this; it is a manufacturing technique, which provides clients with a product essentially identical to conventional hot-mix asphalt. If there is a difference it is that the binder is aged less during the manufacturing processs. CoolPave half-warm asphalt is a significant advance in asphalt technology that provides benefits to the environment, the manufacturing and paving crews, the client and ultimately the tax-paying public. It is expected that hot-mix asphalts will be the exception in only a short time as evidenced by the substantial and enthusiastic uptake of half-warm asphalts in Europe and the United States. AAPA TRAINING COURSES FOR 2010 Downloads of the 2010 program, course brochures, course outlines and course registration information are available from the website - www.aapa. asn.au/Training/AAPA Training Courses. If you require further information about courses or wish to discuss a customized course please contact: AAPA Training Centre. Phone: (03) 9853 5322 Facsimile: (03) 9853 5914, E-mail: trainingcentre@ aapa.asn.au Web: www.aapa.asn.au 28 ROADS JUNE 2010/JULY 2010
BITUMEN STABILISATION IN SOUTH AFRICA To understand bitumen stabilisation technology (materials treated with bitumen emulsion or foamed bitumen), it is important to know the history of this technology. BSMs have been used in South Africa for more than 30 years. The concept of emulsion treatment came to the fore in the 1970s when a newly constructed freeway suffered a catastrophic premature failure. The failed cemented base material was retreated with bitumen emulsion and most of those sections are still in a satisfactory condition today. The following paper, prepared by DC Collings, Loudon International, South Africa (davecol@iafrica.com), was also featured at AAPA’s 13th International Flexible Pavements Conference. Condensed version - full version available from Conference papers 2009 - aapa@asn,com.au The advent of foamed bitumen in South Africa During 1993, in pursuit of an alternative to bitumen emulsion, a Joint Venture (JV) between a large construction company, a small design firm and a foreign manufacturing company imported a specialised 400 t/hr foamed bitumen mixing plant from the foreign company. The mixing plant was duly established on site in April 1994. The anticipated construction period was four weeks. From the outset, everything that could have gone wrong did go wrong. On the odd occasion when foam was produced, the resulting bitumen stabilised material allowed the 150mm thick base layer to be successfully paved. A rudimentary method for operating the plant was eventually developed, allowing a satisfactory product to be mixed at an exceedingly slow rate. Despite this, the road is still in good condition 15 years later, in spite of the abusive loading it has received from timber haulage. Two major benefits did accrue from these expensive lessons: • foamed bitumen was shown to be a viable and highly attractive substitute for bitumen emulsion as a stabilising agent (the product was good, the equipment was flawed); and • an in-depth understanding of the problems encountered when using an expansion chamber to produce foamed bitumen. The new “properly engineered” system Following this project and a short but intensive research and development effort by the manufacturer’s engineering design team, the prototype spraybar for producing foamed bitumen was subjected to a series of trials in Germany in November 1995. The system was then mounted on a newgeneration recycler and shipped out to South Africa for field trials. Six weeks of continuous work followed before the Germans declared that the system was satisfactory. The system currently manufactured by this company, some 13 years later, is exactly the same. Bitumen stabilisation in South Africa Within a year of completing these trials, four South African contractors had purchased large recycling machines equipped to apply foamed bitumen. These contractors quickly identified the economic advantages to be gained by substituting foamed bitumen for bitumen emulsion in tenders calling for the construction of an emulsion treated base (ETB). As a result, several contracts were awarded in favour of foamed bitumen, in spite of the Road Authority’s uncertainty as to whether or not foamed bitumen was indeed as effective as bitumen emulsion. Subsequent to developing the full-scale system for mounting on large recyclers, a small laboratory unit was developed to support the design aspect of this new technology. TG2 Second Edition and technology development Following the successful use of foamed bitumen the emulsion manufacturers supported the development of two documents through SABITA. However, these imposed a number of limitations. Subsequently a technical guidelines document TG2 was developed and released in 2002. Subsequently experience in South Africa and overseas highlighted deficiencies in TG2 and work was done to review those guidelines. This review took five years to complete with funding provided by SABITA and Gautrans and the new edition of TG2 was published in May 2009. It was titled TG 2 Second Edition, Bitumen Stabilised Materials, A Guideline for the Design and Construction of Bitumen Emulsion and Foamed Bitumen Stabilised Materials. TG2 Second Edition therefore replaces Sabita’s Manuals 14 and 21 as well as the original TG2. Regardless of whether bitumen emulsion or foamed bitumen is applied as the stabilising agent, the same mix design and pavement design procedures are applicable to both and the new method for classifying BSMs takes no account of which stabilising agent was used in the mix. BSM CHARACTERISTICS AND PERFORMANCE BSMs are pavement materials that are treated with either bitumen emulsion or foamed bitumen. The materials treated are either those recovered from an existing pavement or fresh materials. Granular materials, previously cement treated materials or reclaimed asphalt (RA) layers are included. Where an existing pavement is recycled, old seals or asphalt surfacing is usually mixed with the underlying layer and treated to form a new base or sub-base layer. ROADS JUNE 2010/JULY 2010 29
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Page 3 and 4: Chairman’s report ASPHALT REVIEW
Page 6 and 7: ASPHALT REVIEW a range of different
Page 8 and 9: ASPHALT REVIEW AAPA/Austroads Warm
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Page 12 and 13: ASPHALT REVIEW research and quality
Page 16: ASPHALT REVIEW Foamed bitumen The q
Page 19 and 20: The Road to Innovation Ever increas
Page 21 and 22: Fulton Hogan and PRS Join Together
Page 23 and 24: PMS
Page 25 and 26: Boral Asphalt Boral’s LoCarb asph
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Page 31 and 32: days in South Australia to over 250
Page 33: VÖGELE VISION 5103-2 FEATURING HIG

Asphalt Review - Volume 29 Number 2 (June / July 2010)

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