Coal tar was used in Sweden for the production of asphalt and for the drenching of stabilization gravel until 1973. The tar has high concentrations of polycyclic aromatic hydrocarbons (PAH), some of which may be strongly carcinogenic. Approximately 20 million tonnes of tar-containing asphalt is present in the public roads in Sweden. Used asphalt from rebuilding can be classified as hazardous waste according to the Swedish Waste Act. The cost of treating the material removed as hazardous waste can be very high due to the large amount that has to be treated, and the total environmental benefit is unclear. The transport of used asphalt to landfill or combustion will affect other environmental targets. The present project, based on three case studies of road projects in Sweden, evaluates the consequences of four scenarios for handling the material: reuse, landfill, biological treatment, and incineration. The results show that reuse of the coal tar-containing materials in new road construction is the most favorable alternative in terms of cost, material use, land use, energy consumption, and air emissions.
In Sweden, use of industrial by-products is still hindered by concern for their long-term properties. This report describes a three-year research project aiming to identify the key processes of ageing related to the usefulness of by-products in roads; investigate the consequences of these processes for technical and environmental properties of the by-products, and propose a method for accelerated ageing to predict long-term properties. The project has compared naturally aged samples of two by-products used as sub-bases in existing asphalt paved roads with samples of fresh by-products from producers' piles. Steel slag of electric arc furnace type and municipal solid waste incinerator (MSWI) bottom ash were chosen. The samples were thoroughly characterized in order to identify which ageing processes had been crucial. The working hypothesis was that ageing processes lead to changes in pH, effective particle size and mineralogy, which in turn determine leaching, stiffness and stability of the material. One of the conclusions from the project is that the test results confirmed that the pavement edge material is ageing faster than the road centre material is.
Test comparisons have been carried out between road material laboratories in Sweden for particle density and water absorption according to SS-EN 1097-6:2013 in 2020. The comparison was made with four materials, two with the grading 11/16 mm and two with the grading 0/4 mm. Each participant performed double tests of each material. There were 49 laboratories participating.
Generally, are there small variations for particle density between the participants. The coefficient of variation1 is less than 1%. For the water absorption, the variations between the participating laboratories are relatively large. However, this can partly be explained with that the results consists of low values and the "natural" variation is almost as great as the results, about 0.3%. Water absorption has just under 30% in variation coefficient1for the coarser materials in grading 11/16 mm and about 60–70% for the finer ones in grading 0/4 mm.
Clearly anomalous participants for particle density for the finer materials is laboratory number 20 with very low results, where even laboratory No. 6 is located low. For water absorption, is it mainly laboratories 33, 12 and 50 that most clearly stand out in a negative way. In general, are the repeatability and the reproducibility, in this comparing analysis better or equal with SS-EN 1097-6:2013.
To study the correlation between the degradation of unbound base layer and mechanical properties (primarily Los Angeles test but also micro Deval test) a number of materials has been exposed by wheel load of VTI’s Heavy Vehicle Simulator (HVS). The first round was performed during the winter 2010–2011 and the second round during the following winter. In each round there were five materials tested. In the second round there were four new materials and one “old” as reference material. In this report results from round II will be presented, as well as some common results from both of the rounds, I and II. The results from round 1 are presented in VTI notat 4-2011. (Håkan Arvidsson: Comparison between the Los Angeles value and degradation from traffic load).The degradation has been defined as the difference in grain size distribution before and after HVS test. The degradation can be described in several ways. One way is as the difference in the area under the grain size distribution curve, another way is to sum the difference in percentage passing for all sieves or a few, e.g. the increase of fines by using results from the sieves 0.063–0.125 mm. The rutting has been measured by laser. The rutting is inversed proportional to the increase of fines. The increase of fines probably increases the stability in this quite coarse base layer grading. The materials with less increasing of fines have most of the hard minerals (quarts and plagioclase). The conclusion of these two tests on unbound base layer materials is that you partly can explain the degradation (change of grain size distribution) with mechanical properties (like Los Angeles and micro Deval). The correlations confirm this explanation and depend partly on an extreme material. Hellman et al (2013) show that degradation and crushing of the aggregates during compaction have a correlation with mechanical properties by studying microstructure and degree of crushing in microscope. Therefor the conclusion is that there is a degradation and crushing of aggregates in unbound base layer materials exposed by compaction and heavy traffic load.
Rapportsammanställning av föredrag vid forskardagarna i Linköping 1999-01-13--14 beträffande:
Under många år har hyttsten och hyttsand använts som fullgoda alternativa byggnadsmaterial i vägar som bär- och förstärkningslager, eller som lättfyllning i underbyggnad. Egenskaperna för de här materialen har tidigare undersökts i laboratorier och i begränsad omfattning i fält och då uppvisat goda resultat. Syftet med det här projektet är i första hand att genom provbelastning med FWD på ett flertal vägobjekt i Sörmland, som har uppbyggnader med lager som består av hyttsten eller hyttsand, undersöka materialens egenskaper och funktion i vägen. Detta kan sedan ligga till grund för dimensioneringen av vägar med lager av hyttsten och hyttsand. För undersökningen valdes fem vägavsnitt ut samt ett avsnitt på en gång- och cykelbana, samtliga belägna i Sörmland. De utvalda avsnitten har hyttsten eller hyttsand i konstruktionen. I notatet redovisas även resultat från tidigare undersökningar som gjorts på Rv 52:01 Katrineholm och som är väldokumenterade. För att jämföra de olika sträckorna är det önskvärt att kunna beräkna de olika lagrens styvhet (E-modul). Då uppgifter om lagertjocklekar saknades på flertalet av sträckorna är det inte möjligt att beräkna styvheten, varför andra beräknade mått får användas. De beräknade bärighetsmått som används i jämförelsen är "Uppskattad undergrundsmodul" och "Uppskattad beläggningstöjning" enligt Vägverkets metodbeskrivning 114:2000.
This report describes laboratory testing of specimens taken from four new instrumented test road sections that have been built on E45 close to the Svappavaara municipality in Norrbotten County in Northern Sweden. The structures are located about 100 km north of the Arctic Circle in a climate that is characterized by long cold winters and short mild summers. The four test sections were built in a conventional manner. Each structure is about 200–250-metre-long with a central 100-metre-long part defined as the actual test section. All structures are in total 60 centimetres in thickness resting on top of a 70-centimetre-thick old existing road. The bitumen bound part of all the four structures consists of four layers; a thin surface course layer, two binder layers and a road base layer. All structures have the same wearing course, TSK 16 with a standard 160/220 penetration grade bitumen. The main difference between the structures lies in the binder as well as the two road base layers. As a part of the monitoring programme drilled asphalt specimens were taken in 2013 from the road structure and tested at VTI's material testing laboratory in Linköping. Furthermore, samples were taken from the unbound base course and tested. This report presents the test results for asphalt bound layers as well as for the unbound base course. For the bound layers the testing procedure included volumetric properties, stiffness modulus and fatigue tests for the different types of conventional and polymer modified asphalt mixtures. The tests were conducted in accordance with the Swedish or the equivalent European standards. For the unbound base course fundamental properties were estimated as well as stiffness and permanent deformation properties for different moisture contents.
Mobile reflectometers for measurement of road marking retroreflectivity have been commercially available since the late 1990s. It has been speculated that measurement errors are larger for these mobile instruments than for the traditional hand-held reflectometers. In order to get basic data for a new standard, CEN/TC 226/WG2 asked the Expert Panel to investigate measurement accuracy of mobile reflectometers. This investigation was carried out in a round robin test, in which the three most commonly used instruments in Europe participated: Ecodyn 30, LTL-M and Zehntner ZDR 6020. Two instruments of type Ecodyn were tested and one of each of the other two instruments; thus four reflectometers participated in the test. These instruments were denoted No. 14.
A test route of 19 edge lines and 2 lane lines was defined. All edge lines were continuous, plane or profiled, while the lane lines were plane, 3 metres long with a gap of 9 metres. At each test site a section of 200 metres was measured, twice with each instrument. As reference, a hand-held reflectometer of type LTL-2000 was used. At each test site, a number of 3238 readings were taken with this instrument.
The aim of the conference is to meet and discuss and get more knowledge of the challenges of road infrastructure asset management. The effects of increasing traffic, climate change and need of safety as well as the need of well-being has to be met by even more effective road management. A holistic approach covering a lifetime view of road keeping (e.g. LCA) and preserving the assets is essential. The challenge Europe is facing is to use environmental friendly materials and technologies providing a sustainable and safe road infrastructure system. The conference covers all aspects of the road infrastructure including assets such as pavements, engineering structures and road equipment.
Natural sand deposits and waste screenings from gravel pits and quarries are abundant in parts of Sweden. Investigations have been made to stabilize such materials with binders based on waste materials. Both laboratory work and test roads have been performed. In the latter case, mainly secondary roads have been strengthened with a plant-mixed bases. Good results have been achieved with a binder made of milled granulated blast furnace slag, activated with lime or especially with both lime and waste gypsum. Sand and screenings from gravel often contain organic material, deleterous with the binders studied. In such cases, the gypsum addition also seems to counteract the negative effect of the organic material. Fly ash has recently been available in Sweden. Tests made with fly ash-lime, as often used for stabilization abroad,have shown too slow binding for a rather cold climate. Addition of waste gypsum, calcium chloride, alkali-salts or use of an alkali-rich cement kiln dust instead of commercial lime can improve the binding properties. Different fly ashes, however, react in different ways. It is often more suitable to use fly ash-cement as a binder, especially with poorly graded aggregates. The fly ash, added in an optimum amount, work as a filler and high immediate stabilities can be achieved at a correct water content. The puzzolanic properties of the fly ash, at the same time, makes it possible to reduce the cement content considerably in comparison with the case when only portland cement is used as a binder. Promising laboratory work has also been done with binders consisting of condensed silica fume or ash from fluidized bed coal combustion, both in combination with lime.
Försöket inriktades på att undersöka om polymermodifierade bindemedel (PmB) kunde förbättra egenskaperna hos slitlager av tät asfaltbetong (ABT16) och skelettasfalt (stenrik asfaltbetong, ABS16). VTI:s uppgift var att dokumentera utförandet av provvägen, att följa upp vägen långsiktigt och att utvärdera försöket. Uppföljningarna omfattade perioden 1989 fram till sommaren 1999 då vägen lades över på grund av motorvägsarbeten. Uppföljningen har bland annat omfattat dubbslitage, spårbildning, jämnhet, textur, friktion samt undersökningar av beläggningsprov (massa och borrkärnor) och bindemedel.
A round robin was carried out by seven different laboratories in Sweden for four different types of bituminous binders, two harder bitumen and two soft bitumen. The purpose of the round robin test was to compare the viscosity methods using capillaries against the new variant with a rotating spindle viscometer. Apart from these methods the aging characteristics was also tested but later not evaluated. Much data were collected from different variations on these analyzes and the focus has been on evaluating data from EN 13302, EN 12595 and EN 12596, which was the main purpose of the round robin. The evaluation has focused on the reproducibility for the various methods compared with the precision in the different standards. The variation in the result for the method SS-EN 13302 was generally lower in this round robin test compared to the precision in the standard while the variation for the SS-EN 12595 and SS-EN 12596 generally was higher.
Cold recycling of asphalt is a resource-saving technology because the materials do not need to be warmed up. Moreover, by using this technique, up to 100 per cent reclaimed asphalt concrete (RA) could be recycled. However, in order to achieve good results, the old RA should be processed in a proper manner. The report presents results of tests carried out on road N-714, part Vessigebro–Ätrafors and road N 530, part Såghuset–Skönhult in Halland in addition to road D-976, Strängnäs and road D-957, Vansö in Södermanland. Moreover, this report presents results of tests performed on road X-583, part Ljusne–Sandarne in Gävleborg. The mechanical properties have been investigated by indirect tensile strength and stiffness modulus for RA mixtures and drill cores. The tests results showed that part of the damage that may be encountered when using cold recycled asphalt coatings can be in the form of loss of surface materials, mechanical damage due to relatively soft road surfaces and unevenness of the road surface.
It is well known that the determination of fundamental engineering properties of materials is the key to their inclusion within quality control assessments and pavement design. Although using of maximum dry density and optimum moisture content has been widely accepted in quality control assessments, it may not provide the mechanistic properties of the compacted material, namely, strength or stiffness. On the other hand, the static plate loading test used for quality control of roads is relatively expensive as compared with lighter equipment used nowadays to control the bearing capacity of compacted unbound materials. In this context, it has become necessary to find a simple and quick test that can be used in assessing the bearing capacity of Swedish base course material. For this purpose, several unbound granular California bearing ratio (CBR) samples were prepared and compacted using modified Proctor compaction for a wide range of molding water contents. Then, the CBR samples have been tested by a dynamic California bearing ratio device. This research provides a data base for future adopting of the dynamic CBR test as a light equipment used for quality assurance during roads construction. Regression equations have been developed to predict the laboratory dynamic CBR (CBRLD) from the molding water contents and the dry densities with relatively high correlation coefficients. These equations can be used in predicting the CBRLD values for unbound granular materials compacted and tested at similar conditions as in that developed for.