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Report on the USA visit of ZAS delegation (NAPA, Asphalt Institute and PAIKY)


The 11 member delegation of the extended ZAS, Slovenian Asphalt Pavement Association's Management Board, has between the 8th and 16th May 2015, visited the leading representatives of the main North American asphalt organizations: NAPA, Asphalt Institute and PAIKY, Plantmix Asphalt Industry of Kentucky, in the United States of America.

NAPA and AI are American asphalt establishments that cover the majority of asphalt and bitumen production in the United States. That can be stated by the annual meeting World of Asphalt, which attracted more than 7,500 participants to Maryland in March this year.

We have received a remarkable reception. The hosts enabled us to see quarries, asphalt plants and construction sites in addition to numerous professional presentations.

We also presented our work at ZAS and showed the state of the asphalt paving in Slovenia. Presentation, presented by ZAS President (pdf) >> 

The visit strengthened our connections and opened many possibilities for future cooperation. From the individual institutions, the following experts were present:

NAPA, National Asphalt Pavement Association

Reception and professional presentations:

  • -          Michael Cote - NAPA Chairman of the Board and Executive Vice President of building company LANE, The lane Construction Corporation
  • -          Mike Acott - President
  • -          Dr. Audrey Copeland - Vice President
  • -          Kent Hansen - Director of Engineering

AI, Asphalt Institute

Reception and professional presentations:

  • -          Linda Allin –  Director of Finance & Administration
  • -          Mike Anderson – Director of Research and Laboratory Services
  • -          Dr. Mark Buncher – Director of Engineering
  • -          Phil Blankenship – Senior Research Engineer

PAIKY, Plantmix Asphalt Industry of Kentucky

Reception and professional presentations:

  • -          Brian K. Wood - Executive Director
  • -          Nick Rodgers - Marketing Director
  • -          Grant Gabbard – Executive vice president of building company The ALLEN Co. INC


Basic data on the asphalt production in the United States:

  • -          350 million tons of asphalt produced.
  • -          In 2013, they used 73.5 million tons of recycled asphalt (RAP) and 1.7 million tons of shingles (RAS) in asphalt production, which allowed industry to save 2 billion USD.
  • -          NAPA covers about two thirds of the asphalt mixture producers in the States.
  • -          The greater part of the producers produce between 100,000 and 500,000 tons of asphalt mixture.
  • -          In the US there are 249 companies and 1,281 asphalt plants.
  • -          The country has 38 national asphalt associations connected by the NAPA.

NAPA with its 25 member team of mostly engineers puts a lot of work on technical issues, and succeeded with work in many expert committees: in collaboration with federal and local administration, expert meetings, working on expanding the use of social media, the internet and others. They are propagating pavement structure with long life (Perpetum Pavements).

If in the past, the knowledge was with the client, the last decade mainly transferred it on the contractor, who also takes the full responsibility for the successful completion of the work. For this reason, they focus a lot on education, learning and creating a positive image of asphalt and asphalt industry profession in the public. Re-use of asphalt in ever larger scale (up to about 40%) is the main target of the industry, whereby the production as a whole, the proportion of asphalt that contains asphalt milling residue is already about 30%.  

Exceptional results were achieved when using warm asphalt, which has already covered a one-third share of the total production in USA. They mainly use water for foaming (Foam asphalt), which allows them to additional installed device (value around $50,000) to the asphalt plant. As such, warm asphalts, to a lesser extent, lower energy consumption and allow much wider range of transport and installation. For even greater effects of warm asphalt, which has a very positive impact on the environment and safer job environment for workers using chemical additives.














NAPA President, Mike Acott











Mike Acott and Kent Hansen during Slovenian presentation




Dr. Audrey Copeland











Kent Hansen




Slovenko Henigman,  ZAS President has presented ZAS and asphalt paving in Slovenia 











Thanks to the host




Andrej Lavrenčič, Andrej Poglajen, Dejan Poglajen











Roman Bašelj, Zvonko Cotič, Mitja Čotar




















Asphalt institute

Asphalt Institute is an international economic association of bitumen producers, founded in 1919. They unite more than 90% of domestic bitumen producers and record growth of new members from international manufacturers. They provide 5 strategic areas of member support:

  • -          Integrating membership
  • -          Promotion of bitumen
  • -          Technical examples and guidance
  • -          Education
  • -          Environmental protection.

In their headquarters and laboratories in Lexington, Kentucky, they employ 25 highly skilled professionals, covering all the areas mentioned. They have one of the richest libraries on this topic.

Based on a large research project SHRP they determined 5 US federal regions, representing a rounded whole for designing asphalt mixtures and the use of different types of bitumen. In each of these regions and in Canada they have employed one of the top consulting engineers who supports their members and federal institutions.

Their tradition, approach, education, training in laboratories and publications, magazines and books have already carried the voice of their work to the world some years ago, so they also have international members, their experts are welcome as speakers at professional conferences and meetings.

























Greetings from Phil Blankenship




Mike Anderson











Brian K. Wood, Executive Director PAIKY




Dr. Mark Buncher











Getting ready for the presentation




Asphalt Institute laboratory






























Thanks to the Asphalt Institute 










ZAS delegation in front of Asphalt Institute






Plantmix Asphalt Industry of Kentucky unites 32 producers and 36 associative members posed by laboratories, engineering and suppliers. In a country with 120 asphalt plants, they organize annual meetings, exchanges, linking industry and represented the federal institutions and communicating with federal state authorities and administration.

Mostly all their plants have a continuous production capacity of about 500 tons per hour. In urban areas where there is sufficient asphalt milling residue, they use it in a range between 25 and 30%. 

They do not have so much international exchanges, but were impressed by a visit to Japan in 2014 and there is also a possibility to visit Slovenia this year. In particular, they are interested in our industry and work.











PAINKY and ZAS Presidents


-          Quarry

We looked at the unique quarry of THE ALLEN CO. INC company, where by the way of underground mining, limestone is obtained. The quarry was opened in the 1950s. The annual capacity of extraction of limestone is in range of 1.5 to 2 million tons, the procedure provides for quarrying and transport via conveyor belt to the surface. Until now they have come to the third floor underground (approximately 70 m), between the excavated floors there is similar thickness of the floors, which are not excavated. The mine is accessible by a large dumpers, ceilings are installed in increments of 1.6 m, with anchor length of about 3 m.














Entrance to the quarry











70 m under the ground




Limestone trasport with conveyor belt
















-          Asphalt plants

We looked at two continuous asphalt plants and one batch. Essential characteristics of these plants are as follows:

  • -          Continuous production of large capacities, up to 700 t/h.
  • -          Work without sieves on plant, material goes through dosing equipment to a hot drum and mixer.
  • -          The middle of a hot drum is designed to supply asphalt recycling - RAP, already heated in the previously hot stone aggregate.
  • -          The quantities are large, the range of different types of mixtures of bitumen and additives is smaller at drum plants than at batch plants.
  • -          Asphalt plants usually have in their own composition laboratories, the owner of the plant is normally only one constructor.
  • -          The greater part of the asphalt plants have equipment for the production of warm asphalt, but unfortunately we were not able to see this production.














Virginia Paving Company asphalt plant 






























The Allen Inc. asphalt plant

















-           Asphalt paving

We visited two construction sites, renovation of local road in the commuter town and work on the highway. On the local road, the existing asphalts were replaced with new ones. Despite the inadequate baring capacity of the sub grade, they built a bearing asphalt layer, wherein the non-load bearing surfaces are going to be removed again, to improve bearing capacity, and replaced.

On the highway, there was replacing of the wearing course on the section length of 14 miles. We visited laying of asphalt mixtures on the emergency lane. The work was done with the traffic on 6-lane motorway, there were two closed lanes in one way and two were open for traffic.

Main characteristics of incorporation were as follows:

  • -          Extremely fast laying (more than 20 m per minute)
  • -          Extremely high efficiency of laying, less compaction of the finisher
  • -          Rolling with two rollers, but a very heavy
  • -          An essential feature that monitors is density of the layer (void content). 










Hosts with NAPA President Michaelom Cotejem(first from right)




ZAS and Virginia Paving Company











Asphalt laying







The visit of Slovenian delegation was without a doubt extremely successful. We were given some additional views and consolidated some of our beliefs. The most important can be summarized as follows:

  • - In the US, production without the use of an increased amount of asphalt recycling (RAP) in asphalt mixtures is unthinkable. Certainly, in Slovenia we have a lot of options and a duties for a progress, in this area.
  • - Warm asphalts are a fact, offering many, though sometimes difficult to measure, positive impacts. There are energy savings, increased possibility of time-span for the transportation and laying, better working conditions for workers and a positive impact on the environment. US has in this area strongly outpaced Europe.
  • - Thickness of projected asphalt layers: based on the extreme thickness in the past (15 or more inches, which is more than 36 cm), they have decided that the thickness should be slightly reduced, leading to lower production volumes. In Slovenia, we are faced with the inverse situation, as we always had the border thickness where it is necessary to design it carefully because the damage on planned under dimensioned carriageway construction is irreparable.
  • - The use of dynamic tests on bitumen and asphalt, which has established itself in the US and also in Slovenia, is the right answer for increasing traffic load and climatic changes.   
  • - The need for timely implementation of measures is a problem both in Europe and in the USA. The approach of continuous clarifying and argumentative pressure is correct and should be just as successfully carried out in the United States, other European countries, and also in Slovenia. This is the only way we can hope for appropriate and timely measures.














Final dinner










Andrej Lavrenčič and Borut Willenpart




Primož Petrič and Andrej Poglajen











Tadej Lamut, Dean Donko and Primož Petrič




Thanks from ZAS President Slovenko Henigman to the Asphalt Institute; Linda Allin and Phil Blankenship, first from right Tadej Lamut


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