Analytical Methodology to Determine the Composition of Filler Used in Hot-Mix Asphalt

Abstract

For more understanding about asphalt pavement deterioration in Finland, a premature failure of major arterial Ring Road II surface layers was investigated. Documentation of mix design (MD), construction, and material quality analysis, before and after construction, was reviewed and compared with samples collected from the road. The traditional quality assessment of the pavement by means of binder content and aggregate gradation analysis, air void content, and indirect tensile stiffness and strength, as well as binder tests (penetration, ring and ball softening point, and dynamic shear rheometer), did not provide information on the possible reasons for failure. A discrepancy was then found in the filler composition; the discovery was made by applying the standard analytical procedure of hydrochloric acid solubility, coupled with material composition simulations. This finding (and forensic technique) was positively verified by means of thermogravimetral analysis and X-ray diffraction. Scanning electron microscopy, supported by the BET-adsorption (Brunauer–Emmet–Teller) surface area measurements, suggested that, between the stage of MD and construction, the limestone filler was substituted with a mixture of limestone and fly ash. The filler blends were reconstructed on the basis of the MD report and established forensic laboratory findings. The comparative analysis of reconstructed fillers, by means of Fourier transform infrared spectrom-etry, verified that an almost ideal match was obtained with the latter. Alteration of construction material is suggested as the main reason for discrepancies between the MD and actual properties of the analyzed performance of the wearing course.

Etchable iron content (FETCH) proposed as the missing parameter for the better prediction of asphalt mastic stiffening

“…This was done to provide sufficient reference for the fines and mastic replicated based on the Ring Road II mixture forensic analysis [6,7], discussed further.…”

“…The change of the latter was measured using Increase in the Ring and Ball Softening test, also known as delta Ring and Ball Softening Point test (DR&B) [5]. This study has been commissioned by the Finnish Transport Agency as a part of the forensic study of the failed Ring Road II pavement in the metropolitan area of Helsinki [6,7]. We previously reported the discovery of the raw material substitution between the stages of mix design and construction of the surface wearing course as the culprit.…”

The oxidation of bitumen witnessed in-situ by infrared spectroscopy

“…Interestingly, reports on multiply recycled asphalt pavements (RAP) in cold regions describe cases of excessive premature pavement failures [15]. The general fraction analysis of bitumens extracted from some of the field collected samples indicated almost 95% of cumulative content of asphaltenes and resins-the value indicating excessive aging, which was surprising and similar only to the values recorded for natural asphalts [16].…”

Development of Specifications and Guidelines for Hot in-Place Recycling in Finland—Outline and Framework

“…The fines passing 0.125 mm sieve were analysed additionally with FT-IR in order to provide qualitative analysis. The surface area (SA) of fines passing 0.125 mm sieve in samples prior to REM'13 was measured according to the procedure described elsewhere (Makowska et al 2014).…”

“…Various hot in-place recycling (HIP-RC) techniques started to emerge and slowly spread around the world. The benefits of HIP-RC type maintenance are plentiful (Hesham et al 2012) and the interest in the techniques as an alternative to milling and hauling is quite high, especially in countries where high quality aggregates are required due to studded tire wear, and the road network maintenance budget is limited (Makowska et al 2014;Li et al 2014;Hesham et al 2012).…”