In 2013, Finland introduced legislation increasing gross vehicle weights (GVW) on a number of trucks. Since the actual impact on road damage is nearly impossible to quantify in advance, the present analysis of road surface measurements is intended to provide knowledge regarding the impact on road damage. Rutting is influenced by many conflated phenomena. To indicate and capture the effect on road damage due to the new maximum GVW for certain truck- and trailer combinations, the analysis follows two different but mutually supporting lines of reasoning, empirical and theoretical, respectively. Analysis of measured rut depth is supported by theoretical calculations. Theoretical findings clearly indicate that the relative increase in road damage induced by higher GVW is larger than the increase in relative payload capacity. There was a rapid fleet shift towards heavier trucks after 2013, and statistical (empirical) analysis of road surface measurements shows an increase in rutting after this introduction.

Aggregate gradation is fundamental concerning asphalt pavement response to loading, especially regarding resistance to permanent deformation. This study assess, in an empirical way, the capability of a gradation-based framework to evaluate the susceptibility to permanent deformation of asphalt mixtures with varying aggregate gradation. The laboratory study was planned to isolate the effect of aggregate gradation by keeping the source of both the aggregates and the binder constant. The work consisted of testing six different asphalt mixtures with varying aggregate gradations using two different methods: wheel tracking and cyclic compression test. Results show that the testing method influences the asphalt mixtures response to loading. The combined normalised result shows a non-significant relationship between the gradation-based framework parameters and resistance to permanent deformation. Additionally, it was observed that the total amount of coarse material have an influence on mixture resistance to permanent deformation.

Rutting is a major distress and is commonly targeted in design-build contracts as a key requirement, but at the same time, contemporary design methods usually provide scarce information on evolution in absolute terms. The objective of this paper is to investigate and analyse rutting results from a large full-scale road test. The analyses concerned magnitudes and the causes of rutting with a main focus on flexible and semi-rigid structures: one Reference, one high-performance asphalt (HPA) and one asphalt on a lean concrete (LC) base. Field measurements and sampling for the current study comprised acquiring transversal profiles and coring pavement samples. The results suggest that for the HPA and the LC base pavements, rutting is mainly caused by studded tyre wear and densification of the asphalt layers. For the conventional reference pavement additional rutting, most likely in the lower layers, was noted.

The effect of stress level on the resilient modulus for binary mixtures of elastic spheres under triaxial loading is investigated using the discrete element method. The secant modulus during the first cycle of unloading is used as an estimate of the modulus after several load cycles due to computational time restrains. Later in the paper, its adequacy as an accurate and efficient estimator is shown. Numerical results are statistically compared with existing relations characterizing the stress dependency of the resilient modulus for real granular materials. It is concluded that the modulus prediction is significantly improved considering the effect of the deviator stress in addition to the confinement stress, obtaining a good correlation between the modulus and the confinement to deviator stress ratio for the numerical mixtures. The stress dependency of a recently proposed soil fabric classification system, based on force transmission considerations at particulate level, is also studied and its correlation with performance investigated. It is found that the relative load-bearing role of coarse and fine components is governed by the deviator to confinement stress ratio. However, the implemented fabric classification is fairly insensitive to changes in this ratio. Regarding resilient performance, interactive fabrics show the stiffest response whereas underfilled fabrics should be avoided due to a potential for instability.

Soft bitumen asphalt concrete is a common paving material in Scandinavia. The purpose of this investigation was to indicate the possibility to compensate for the stiff binder of reclaimed asphalt pavement (RAP) by using softer binders compared to the mix design. Characterization of binder mixing and diffusion were carried out using viscosity measurements and tests on asphalt concrete comprised stiffness modulus and cyclic compression testing. Acquired results suggest that virgin and reclaimed binders mix and the viscosity can be predicted using simple mixing models. In the case of asphalt made from mixing virgin and recycled material, the mechanical properties indicates fully mixed binders and mixing occurs during sample manufacturing. In general, this study suggests that soft asphalt mixtures can be produced using RAP and that nominal binder viscosity of the final product can be obtained by compensating the stiff binder of the RAP by virgin bitumen of a softer grade.

Permanent deformation accumulation of unbound granular layers under traffic plays a critical role in the performance and need for maintenance of pavements and railway structures. In this paper, the ...

Trafikverket vill kunna beskriva friktionen for hela det statliga vagnatet. En rikstackande friktionsmatning ar praktiskt svar att hantera och mycket kostsam medan vi redan idag mater vagytans makr ...

Water affects asphalt pavements in a detrimental way and it is common knowledge that certain combinations of binder and aggregate can trigger premature failures. Asphalt manufacturing relies mainly on experience and continuous empirical testing. To reduce water sensitivity, adhesion promoters are frequently used. In this investigation, focus was on using portland cement and a by-product from cement manufacturing, cement kiln dust (CKD). The hypothesis was that water susceptibility is influenced by the grading of the hydraulically active fillers: a finer grading will give a stronger improvement. The experimental plan comprised, besides a reference material, 3 different cements and 2 CKDs. Water susceptibility was assessed with the tumbler abrasion test using mastic specimens. Potentially negative effects: decreased workability and degraded low temperature properties were investigated by measuring viscosity of filler/bitumen mixes and low temperature cracking properties, respectively. Admixing of hydraulic filler was made by partly replacing the base material filler with hydraulic filler, thus keeping the overall filler content unchanged. Results show that resistance to moisture damage is improved by adding hydraulically active fillers. However, the hypothesis of finer gradings giving stronger response was not supported; all three portland cements gave very similar results. Furthermore, it seems that fractions of added hydraulic filler above 1–1.5 % (mass of total aggregate) do not further increase abrasion resistance. Essentially, no potential drawbacks, decreased workability or increased low temperature cracking, were noted.

ABSTRACT Due to oxidation, breakdown, and leaching, dust suppressants will be lost from the gravel road surface. Methods for residual dust suppressant concentration supervision are a valuable tool for estimating life-length and optimal application rates, and, hence, efficiency of different products. The objective of this study was to identify methods for quantitative analyses of lignosulphonate and chloride, develop and adapt the methods for application on a gravel matrix, and validate the methods using samples collected in-situ. Results strongly suggest that the reliability and repeatability of the developed methods (23% for lignosulphonate and 30% for chloride, respectively) are acceptable for determination of relative variations in residual concentrations of dust suppressed gravel wearing courses.

Elevated fractions of free mica particles in unbound granular materials, used in road constructions, are believed to reduce bearing capacity and influence the hydraulic behavior of the road structure. The objective of this investigation was to study the influence of mica content on the soil water characteristic curve and the dielectric response measured by time domain reflectometry, for coarse granular (maximum particle size 63 mm) materials. Increased fraction of mica was achieved by partly replacing the base crushed rock material smaller than 4 mm, by pure muscovite mica of similar grading, thereby keeping the overall particle size distribution unchanged. Acquired results indicated that, given equal matric suction, the water retention capacity increased with increased amount of mica. Concerning the time domain reflectometry measurements, no influence of mica content could be detected. Determined water contents required adjustment because of the nonlinear distribution of water in the sample.

This paper presents the results of a Round-Robin test to estimate the precision of European method EN-12697-41 "Test methods for hot mix asphalt-Resistance to de-icing fluids". The purpose of the project was to determine precision data according to ISO 5725, ASTM E691 and ASTM C802. The examined test method is intended for use in requirements specifications for airfield de-icing chemicals and/or as a tool for development of such products. Precision statistics, repeatability and reproducibility standard deviations, are based on observed values from six laboratories and six levels, each level comprising four samples. From a general statistical analysis, which was conducted in addition to precision determination, it could be concluded that the most damaging de-icing agents (treatments) were identified by all participating laboratories both in terms of absolute values and by ranks.

Granular material is, perhaps the most common construction material used in civil engineering, being an important constituent in road constructions, railways, embankments, foundations, buildings etc. This paper presents results from triaxial testing, at various water contents using constant confining pressure, of two different continuously graded granular materials with maximum particle size 90 mm and 63 mm, respectively. Furthermore, water retention properties of the unbound materials are presented and examples of water distributions in a common construction are shown. From the results presented, it can be concluded that increased water contents cause a reduction in resilient modulus and an increase in strain ratio. The distribution of water content in the vertical direction is highly nonlinear and the degree of saturation in the unbound layers of a road construction depends to a large degree on the level of the water table.

Consistent material modeling is a prerequisite for a mechanistic approach to pavement design. The scope of this investigation was to statistically evaluate the efficiency of various resilient models commonly encountered in highway engineering. These models were categorized as describing either resilient modulus or shear and volumetric strains. Triaxial tests using constant and cyclic confining pressure were performed on coarse granular materials of various gradings (maximum particle size 90 mm). Two statistical methods, the extra sum of squares F-test and the Akaike information criterion, were used for model comparison. Concerning resilient modulus, the Uzan model provided, in general, a statistically significant improvement compared to the k–θ model. However, this improvement is lost if a constant Poisson ratio is used to predict shear and volumetric strains. In case of the shear–volumetric approach, no single model was most likely to be the best model for all gradings studied.

Coarse granular materials are used extensively in road construction. Bearing capacity can be affected by the water content in the layers of these materials. The ability to estimate water content and to infer water movements is therefore important. The purpose of the work described herein was to determine soil-water characteristic curves and the relationship between relative apparent permittivity and volumetric water content for coarse (maximum particle size 90 mm) granular materials having various gradations. The relative apparent permittivity was measured with the aid of time-domain reflectometry (TDR), and the concurrent matric suction was measured with a tensiometer. Samples were prepared in a steel box and were heavily compacted, and TDR probes and a tensiometer cup were buried within the matrix. The variation in volumetric water content with apparent relative permittivity was found to deviate from the Topp et al. relationship. Soil-water characteristic curves were described using the Brooks–Corey and van Genuchten models. A pronounced hysteresis between wetting and drying paths was observed. For the low water retention coarse materials, measurements of water content might, in general, require correction because of the nonlinear distribution of water in the sample.Key words: pavement, time-domain reflectometry, soil-water characteristic curve, granular material.