Recycled and waste materials from four different sources were investigated as alternatives for crushed rock aggregates in pavement constructions. Two of the materials were coarse fractions of the bottom ash from two incineration plants. The other two materials were crushed concrete from demolished constructions and reclaimed asphalt from road scalpings. Full-scale accelerated tests were conducted on test road-sections constructed with these materials, employing a heavy vehicle simulator (HVS). The materials were also tested in the laboratory e.g., by means of repeated load triaxial (RLT) tests. In both cases, results indicated that the crushed concrete performed the best, followed by the two bottom ash materials and then the reclaimed asphalt. The results from the RLT tests were used to evaluate the model parameters required for simulating the performances of the test-road sections in HVS tests, adopting a mechanistic-empirical pavement analysis tool ERAPave. With this method, good agreements between the measurements and simulations were obtained. Hence, this approach forms the basis for designing pavement sections using these alternative materials for different traffic loading and climatic conditions. With further testing and modelling, it will be possible to create guidelines and design tables for pavement constructions with alternative materials.

Particle size distribution (PSD) is a crucial factor influencing the mechanical behavior of unbound granular materials (UGMs). It also governs the drainage properties, as well as moisture and frost susceptibility, of UGMs. Therefore, optimizing the PSD is essential to achieve the desired properties for use in pavement structures. In this study, seven different PSDs of a crushed rock aggregate were evaluated for mechanical performance using repeated load triaxial (RLT) tests. Three of the PSDs were designed based on the widely used Fuller-Thompson equation, employing different shape factors. The other three were open-graded, drainable types intended for permeable pavements. The final PSD was generated using an optimization method originally developed for asphalt concrete mixtures. The RLT tests were conducted at the optimal moisture content and at 95% of the maximum dry density for each PSD, determined through the modified Proctor method. The analysis focused on the resilient modulus and resistance to permanent deformation for each PSD. The results demonstrated that the well-graded PSD with grading coefficient, n = 0.45 exhibited the highest resilient modulus and the greatest resistance to permanent deformation. The amount of fines influenced performance significantly: an excess of fines, as well as their removal to create drainable materials, negatively impacted mechanical behavior. Additionally, the maximum particle size also showed some effect. The optimization method applied in this study did not perform well, highlighting the need for further refinement of the approach for implementation in UGMs.

Klimatförändringar medför ökade nederbördsmängder, vilket ställer högre krav på dagvattenhantering i urbana miljöer. Traditionella dräneringssystem riskerar att överbelastas, särskilt i tätbebyggda områden med hårdgjorda ytor. Blå-Grön-Grå-konstruktioner (BGG) erbjuder en hållbar lösning genom att kombinera bärighet, dagvattenhantering och stöd för vegetation. Dessa konstruktioner har överbyggnad bestående av bergmaterial utan finmaterial med stort hålrum som tillfälligt kan lagra vatten och finns i två varianter: med dränerande ytbeläggning eller tät beläggning med infiltration via brunnar. I detta projekt har bärighet och infiltrationskapacitet undersökts på fyra platser i Sverige. Resultaten visar att BGG-konstruktioner uppnår likvärdig bärighet som traditionella lösningar och har mycket god infiltration även efter flera års drift. Projekteringsverktyget ERAPave (Elastic Response Analysis of Pavements – Performance Predictions) har använts för dimensionering, och rapporten innehåller även riktlinjer för materialval och upphandling. BGG-systemen visar stor potential för klimatanpassning av urbana ytor och kan med fördel användas på lågtrafikerade gator, gång- och cykelvägar samt torg.

Climate change is leading to increased precipitation, placing greater demands on stormwater management in urban areas. Traditional drainage systems are often insufficient, especially in densely built environments with impervious surfaces. Blue-Green-Grey (BGG) constructions offer a sustainable solution by combining structural load-bearing capacity, stormwater management, and support for vegetation. These systems feature a porous substructure of rock materials without fines that temporarily store water and are available in two types: with permeable surface layers or sealed surfaces with infiltration via inlets and drains. This project evaluated the load-bearing capacity and infiltration performance of BGG constructions at four locations in Sweden. Results show that BGG systems achieve comparable structural performance to conventional designs and maintain excellent infiltration capacity even after several years of use. The ERAPave (Elastic Response Analysis of PAVEments – Performance Prediction) design tool was used for planning, and the report includes guidelines for material selection and procurement. BGG systems show strong potential for climate adaptation in urban environments, particularly on low-traffic streets, pedestrian and bicycle paths, and public squares.

One step towards reducing construction and industrial wastes (CIW) is to enhance their utilisation in road construction. Prior to their implementation, it is essential to evaluate their mechanical properties to ensure suitability and establish design guidelines. With this objective, four CIW materials were tested using repeated load triaxial (RLT) equipment to evaluate the materials’ functional properties, namely stiffness (Mr) and permanent deformation (PD) characteristics. In addition, full-scale accelerated pavement tests (APTs) were conducted where the four CIW materials were used as the subbase layer instead of traditional materials. Thereafter, a mechanistic–empirical (ME) pavement design and performance prediction method was used to predict their APT performances based on the RLT testing parameters. It was found that the ME performance method can adequately predict the CIW´s rutting development. The approach presented here, therefore, can facilitate the development of design guidelines and the increased utilisation of CIW-based materials in road construction projects.  

This study examines pavement responses under six tire types: two conventional duals, one conventional single, two first-generation widebase (FGWB) and one new-generation wide-base (NGWB) tire. Full-scale accelerated testing using a Heavy Vehicle Simulator measured stresses and strains in pavement layers under varying wheel loads, inflation pressures and lateral wander. Tire footprints were also recorded. Single tires caused higher strains in the asphalt concrete layer and greater stresses in unbound layers than dual tires, increasing the risk of fatigue cracking and permanent deformation. Among single tires, the NGWB 455/55R22.5 caused the least damage, while the FGWB 425/65R22.5 caused the most. Damage ratios showed that single tires were considerably more damaging than duals, depending on load and damage type. Increased load consistently raised stress and strain levels. However, inflation pressure effects varied: NGWB and dual tires showed decreased pavement responses with higher pressure, while other tires showed the opposite trend.

Waste materials and biproducts from various industries can be a good alternative source of pavement materials. This will reduce the demand for natural aggregates. Instead of dumping as landfill, using these materials in pavements will significantly contribute to obtaining climate neutrality and circular economy. However, based on the sources, the properties of these materials can vary widely. Knowledge and experience regarding the suitability and performance of these waste materials in pavements is not as extensive as conventional materials. Hence, prior to employing in pavement constructions, it is necessary to investigate the mechanical properties of these materials in a systematic manner and to create guidelines for their usage. 

In this study, recycled materials from four different sources were investigated as alternatives for pavement constructions. Two of the materials were coarse fractions of the bottom ash from two incineration plants. The other two materials were crushed concrete from demolished constructions and material from road scalpings. Both laboratory and full-scale accelerated tests were conducted. The objectives were to compare their relative performances and to obtain and calibrate the material properties for further design using a pavement design tool ERAPave.  

The laboratory investigations were based on repeated load triaxial (RLT) testing. From the RLT tests, the stiffness and permanent deformation properties as well as the model parameters used in ERAPave for each of these materials were evaluated.  

For the full-scale accelerated tests, four instrumented test structures were built where all the layers were identical except for the subbase layers which were composed of each of the alternative materials. These structures were then tested employing a heavy vehicle simulator (HVS). During the passages of the wheel of the HVS, development of the surface rutting as well as deformations and stresses in the different layers were registered.  

In both laboratory and full-scale tests, results indicated that the crushed concrete performed the best which is comparable to well-graded crushed rock aggregates. Material from road scalpings demonstrated the weakest performance followed by the two bottom ash materials.  

This paper presents the evaluation of the relative pavement damage caused by a high-capacity transport (HCT) 5 axle truck with respect to three other reference trucks consisting of 4, 3 and 2 axles. The analysis was conducted by simulating the responses of three pavement structures using the pavement analysis tool ERAPave. Two damage criteria of the pavement structures were evaluated: fatigue cracking of the asphalt concrete (AC) layer and permanent deformation of the subgrade. The relative damage caused by the different vehicles were estimated by calculating a damage factor (Dr) following the Asphalt Institute Method. Three loading scenarios of the trucks were analyzed: (a) one way trip with fully loaded trucks, (b) round trip where the return trip consisted of the empty vehicles with lifted axles and (c) round trip where the return trip consisted of the empty vehicles without lifting any axles. The damage factors were calculated for per ton of carried load and were normalized with respect to the 2-axle truck. Results indicate that the relative impacts of the vehicles depend on the structure type and seasons. Generally, the 4-axle truck appeared to be the least damaging one. The HCT 5-axle truck is more damaging than the 4-axle truck, but less damaging than the other two.

Infrastrukturprojekt använder stora mängder resurser i samhället. För att minska klimatpåverkan är alternativa konstruktionsmaterial en väg framåt. Dock saknas ofta viktiga materialspecifika parametrar för dimensionering av konstruktioner med sådana material. Detta blir ofta ett hinder i upphandling och utformning för att möta behoven (tex trafikklass, hållbarhet och framtida underhållsbehov). Detta projekt är inriktat på att möta dessa problem. Det övergripande syftet är att få till en väl fungerande återvinning och cirkulär hantering av sekundära ballastråvaror och skapa förtroende för materialen i syfte att möjliggöra en ökad användning. Projektet vill också förenkla användning av slaggrus. Till skillnad från de projekt som genomfördes under 1990-talet och början av 2000-talet ingår här en systemanalys och genomlysning av affärsmodeller. Ett problem som identifierades var att materialmängden ofta är för liten för stora vägprojekt. Projektet har därför inriktat sig på användning i urban miljö där mindre volymer krävs och transportsträckorna är kortare. Syftet med detta delprojekt är att undersöka möjligheten att ta fram underlag och materialparametrar för dimensionering av konstruktioner med slaggrus (och andra restmaterial).

Det dimensioneringsprogram som används är ERAPave som är framtaget på VTI för Trafikverkets räkning och kommer ersätta nuvarande dimensioneringssystem. Genom att slaggrus kommer finnas med i materialdatabasen kommer det förenkla användningen och dimensionering framöver. För att ta fram styvhetsdata och nödvändiga materialparametrar för slaggruset har laboratorieförsök och Triaxialförsök gjorts på två material. För att verifiera materialparametrar och dimensioneringsmodellen har fullskaleförsök med Heavy Vehicle Simulator (HVS) utförts. Försöken innebär en accelererad provning av konstruktioner där slagg används. HVS utrustningen simulerar realistisk trafikbelastning genom att ett hjul belastar konstruktionen upprepade gånger vilket efterliknar riktig lastbilstrafik. Konstruktionen utsätts för stor trafikbelastning på kort tid. Påverkan på konstruktionen kan följas med sensorer och effekter som exempelvis spårbildning och påkänningar studeras.

Infrastructure projects use large amounts of resources in society. To reduce the climate impact, alternative construction materials are a way forward. However, important material-specific parameters for dimensioning constructions with such materials are often missing. This often becomes an obstacle in procurement and design to meet the needs (eg traffic class, sustainability and future maintenance needs). This project is aimed at addressing these issues. The overall aim is to bring about a well-functioning recycling and circular handling of secondary aggregate raw materials and create confidence in the materials in order to enable increased use. Unlike the projects that were carried out in the 1990s and early 2000s, this includes a system analysis and clarification of business models. A problem that was identified was that the amount of material was often too small for large road projects. The project has therefore focused on use in urban environments where smaller volumes are required and transport distances are shorter. The purpose of this sub-project is to investigate the possibility of producing a basis for the dimensioning of constructions with crushed stone (and other residual materials).

The dimensioning software used is ERAPave, which was developed at VTI on behalf of the Swedish Transport Administration. In order to obtain stiffness data and material parameters for the crushed stone, laboratory tests and triaxial tests have been carried out. To verify material parameters and the dimensioning model, full-scale tests with the Heavy Vehicle Simulator (HVS) have been performed. The trials involve accelerated testing of constructions where slag is used. The HVS equipment simulates realistic traffic loads by repeatedly loading a wheel on the structure, which simulates real truck traffic. The construction is exposed to heavy traffic in a short time. The impact on the construction can be monitored with sensors and effects such as rut formation and stresses are studied.

Permanent deformation is one of the failure modes considered in the analysis and design of flexible pavements. ERAPave performance prediction (PP) which is a mechanistic empirical (ME) pavement design tool utilises two distinct models for the prediction of permanent deformation in the bound and unbound granular layers including subgrade. This paper aims to calibrate these models using pavement response and performance data from accelerated pavement testing (APT) structures. Material properties such as layer modulus were established through an optimisation that involves both falling weight deflectometer (FWD) and pavement response measurements. Based on the predicted performance results, a separate set of calibration was performed for permanent deformation development in moist and wet moisture conditions. The calibrated models have resulted in predictions that are in good agreement with observed performances. Furthermore, the model parameters successfully captured the initial densification behaviour and the associated sensitivity with axle load level.

An existing permanent deformation (PD) model for the unbound granular materials (UGMs) in pavements, developed based on multistage (MS) repeated load triaxial (RLT) tests, was modified to better suit to field conditions and software applications. The model was calibrated for a few UGMs with a series of moisture contents (w) using MS (to include the stress-history effect) RLT tests and was validated by predicting the PD under different sets of stress levels and w's. Generally, it exhibited improved predictions over the Mechanistic-Empirical Pavement Design Guide (MEPDG) model. The model was further applied for field conditions and was implemented in a pavement design software entitled ERAPave PP, using data from accelerated testing of three structures employing a heavy vehicle simulator (HVS). Based on additional MS RLT tests, a guideline for the ranges of the material parameters for different types of UGMs was presented.