Evaluation of INDOT Construction Smoothness Specifications

Currently, Indiana Department of Transportation (INDOT) is using the California Profilograph as the standard measuring device in its smoothness specifications. The output derived from the profilograph is called Profile Index (PI). PI represents the total accumulated deviations of the profilograph output traces beyond a tolerance zone (blanking band). At present, INDOT is using 0.2-inch blanking band to evaluate the profile traces, which has raised some concerns because some small unpleasant surface irregularities are covered by the blanking band. The major objective of this study was to develop a rational method for interpreting profilograph traces using 0.0-inch blanking band (zero tolerance) method and to establish corresponding pavement smoothness specifications. The secondary objective was to develop/adopt an automated system for the pavement profile analysis from printed profilograph traces. The study was divided into two parts. In the first part (synthesis study), a literature review was conducted to obtain information of smoothness specifications, smoothness measuring devices, and indices. Profilograph traces from several completed paving projects were analyzed using 0.2-inch and 0.0-inch blanking bands to develop manual reduction procedure for the 0.0-inch blanking band Profile Index. In the second part of the project, new PI0.0 construction smoothness specifications were developed by converting current PI0.2 smoothness specifications to the new PI0.0 specifications using developed conversion models. The converted PI0.0 specifications were then compared with the current Kansas DOT (KDOT) and other PI0.0 specifications. A partial verification of the converted PI0.0 specification was done by calculating pay factors for several recently completed paving projects measured using California profilograph. Measurement results were reduced manually and automatically by the Proscan system, which includes scanner and analysis program to reduce printed traces. It has been developed by Kansas State University and currently KDOT is using it in their construction QA procedures. The Proscan system showed excellent repeatability, and it saved considerable amount of time compared to the manual trace reduction. It is therefore recommended that INDOT uses Proscan system in their constitution QA operations. The converted PI0.0 specifications were also modified to comply with the Proscan reduction results

Composition of abraded dust from asphalt pavement produced using ferrochromium smelter slag (OKTO-aggregate)

This report describes an investigation that took place at Aalto University commissioned by the Finnish Transport Agency about asphalt dust containing OKTO-aggregate. In the fall of 2013, Finnish newspaper headlines began to raise the issue of the occurrence of damaged timing belts in the Oulu region. It seemed to only concern certain models and was found in the form of a dust. The press reasoned that this "mysterious" dust must have originated from the aggregates abraded from the local Oulu roads. More specifically, it was attributed to the OKTO-aggregate used in surface wearing course mixtures on high traffic volume roads. The OKTO-aggregate (OKTO-murske in Finnish) is a brand name for the man-made byproduct of the smelter slag from the Outokumpu Tornio ferrochromium plant. Natural rock aggregates are substituted by this material in high volume roads due to its excellent abrasion resistance against studded tire wear. The conclusion is that the possible contribution of OKTO-aggregate to the mechanical breakage or abrasion of car parts was considered insignificant compared with the other fragments, such as corundum, that were also detected in the car dust. Furthermore, OKTO-aggregate was found to be much less reactive with deicing salts than the rock aggregate used in the Oulu region. Therefore, the OKTO-aggregate does not significantly contribute to the chemical corrosion of car parts

Durability of Ring-Road II asphalt pavement - Phase I report on forensic analysis of Ring-Road II pavement distresses

This report presents findings from prematurely failed pavement of Ring-Road II (Kehä II) in Espoo, Finland. The road had excessive potholes, cracking, raveling and stripping only five years after construction. Core samples taken for this study revealed also that pavement layers were partially separated due to the lack of bonding. Research focus was to determine the causes of Stone Mastic Asphalt surface layer failure. Documentation of mix design, construction and material quality analysis, prior to and after construction, was compared to the samples collected from the road. Traditional quality assessment of the pavement by means of binder content and aggregate gradation analysis, air voids content, Indirect Tensile Strength and Stiffness, as well as binder tests including Penetration, Ring and Ball Softening Point and rheological characterization by Dynamic Shear Rheometer (DSR) were performed. Discrepancy was found in filler composition and additional analysis was made by applying standard analytical procedure of hydrochloric acid solubility. The findings were confirmed by means of Thermogravimetral Analysis (TGA), X-Ray Diffraction (XRD), and Scanning Electron Microscopy (SEM), supported by BET-adsorption surface area measurements. The investigation revealed presence of fly ash that was apparently used for extending limestone filler during construction. It can be concluded that the main reason for the pavement failure was due to this substitution and the consequent problems that followed in the construction and thereafter in the pavement performance

Assessment of air void content of asphalt using dielectric constant measurements by GPR and with VNA

For several years, Ground Penetrating Radar (GPR) has been used in Finland to evaluate the air void content of asphalt pavements. Air void content is an important quality measure of pavement condition for both old and new asphalt pavements. The objective is to investigate if the existing GPR technique and application employed in Finland is sufficiently accurate to be used as a quality control tool in assessing the compaction of newly laid asphalt pavements. The work comprised field and laboratory experiments and a review of the existing PANK calibration method for the GPR measurements. Field experiments were conducted in the summer of 2013 on highways Vt3 and Vt12, near the City of Tampere. The test roads were paved with SMA16 using an approx. 40 mm thick layer of new asphalt. Roads were measured with GPR several times during the fall of 2013. A total of 36 cores and 2 slabs were obtained from the roads and tested in the laboratory with a Vector Network Analyzer. Measurements were done with a 7 to 17 GHz transmission configuration to measure the reference dielectric constant of the asphalt mixture. A major finding is that the PANK calibration method for the GPR inadvertently reduces observed density variations and may introduce a systematic bias. This makes pavements appear to be more homogenous and dense than they actually are according to conventional measurements.Maatutkaa (Ground Penetrating Radar, GPR) on käytetty Suomessa pitkään asfalttipäällysteiden tyhjätilan määrittämiseen. Tyhjätila on tärkeä kriteeri sekä uusien että vanhojen asfalttipäällysteiden laadun selvittämisessä. Tavoitteena on tutkia, onko Suomessa tällä hetkellä käytössä oleva GPR-tekniikka ja sen soveltaminen tarpeeksi tarkkaa uusien asfalttipäällysteiden tiiveyden mittaamiseen. Työ koostui kenttä- ja laboratoriotutkimuksista sekä GPR-mittausten kalibrointiin käytetyn PANK-kalibraatiomallin arvioinnista. Kenttäkokeet suoritettiin kesällä 2013 Tampereen lähellä valtateillä 3 ja 12. Teiden päällyste oli tyyppiä SMA16, ja uuden asfalttikerroksen paksuus oli 40 mm. Tiet mitattiin 1 GHz maatutkalla useita kertoja syksyn 2013 aikana. Teiltä otettiin 36 poranäytettä ja 2 laattanäytettä, jotka testattiin laboratoriossa vektoripiirianalysaattorilla. Asfalttiseoksen dielektrisyysvakio mitattiin 7-17 GHz läpimittauskonfiguraatiolla vertailuarvojen saamiseksi. Tärkein havainto oli se, että PANK-kalibraatiomallin käyttö maatutkamittauksissa vähentää havaittuja tiheyden vaihteluita ja saattaa lisätä systemaattisen virheen mittauksiin. Tämä saa päällysteet näyttämään tasalaatuisemmilta ja tiiviimmiltä kuin mitä ne oikeasti ovat

Assessment of air void content of asphalt using dielectric constant measurements by GPR and with microwave radar

In this report, we have presented microwave radar and GPR measurements as well as laboratory tests conducted in 2014-2016. The microwave radar was tested in three different construction sites. In addition, GPR measurements were obtained for comparison. Laboratory tests included traditional density measurements and 7-17 GHz VNA scanning of drill cores obtained from the test sites. A new laboratory measurement method using cavity resonator principle was introduced with promising results. Testing of this new method will be continued. The results indicate no clear correlation between air void content and GRP permittivity measurements. Permittivity is sensitive to the changes in the relative permittivity of aggregates and volume portions of aggregates and bitumen. The relative permittivity of the aggregates determines the base level for permittivity measured with radar or VNA. In the course of this research, it has become apparent that a new calibration procedure for the GPR measurements is needed. The aim in further research is to extract core samples from pavement areas with different densities to obtain a local calibration model