Johan Colin

Experimental investigation of the homogeneity of the blended binder of a high rate recycled asphalt

Nowadays, with the increasing material costs and the environmental needs to reduce energy consumption and greenhouse gases emission, the technique of asphalt recycling becomes more and more used in the road industry. To ensure the performance of recycled asphalt, a quality control of the bituminous mixture is required. In this context, this work was carried out within the framework of a partnership between the IRC/ESTP and the company Eurovia. In this paper, we present an experimental approach to characterise the level of blending of the binder from reclaimed asphalt pavement (RAP) in hot recycled bituminous mixture. First, a series of laboratory tests are performed on asphaltic concrete including 70% of RAP to extract the bituminous binder mixture using an appropriate solvent. This leads to define an appropriate progressive extraction procedure that allows a regularly stripping of the recycled concrete (three solutions containing about 30% of the bituminous binder). Then, both conventional tests and infrared spectroscopy analysis are performed in order to quantify the evolution of the RAP and virgin binders mass proportions during the stripping process. The experimental results show a “bad” remobilisation of the virgin bitumen in the blended binder of the hot recycled bituminous mixture. This finding correlates with the hypothesis of the “heterogeneous asphalt” considered during the manufacture process.

Prediction of the rutting potential of bituminous binders using a stochastic approach

This work deals with the experimental characterization of the mechanical behavior of bituminous binders used in road pavement. First, conventional tests are used to determine the grade of four bituminous products with a Polymer modified one. Then, rheological experiments were performed to compare the viscoelastic properties of the different binders. Tests were carried out at least three times so that one can take advantage of the statistical collected data to define the available information used in the stochastic modeling. The parametric probabilistic model highlights the necessity to include experiments uncertainties into modeling for a safe and accurate prediction of bitumens ultimate properties.

Probabilistic parametric approach for rutting evaluation: application to hot and warm asphalt

This paper deals with a stochastic approach to evaluate the rut depth of hot and warm bituminous mixtures. First, the rutting performance of both mixtures using the French rutting tester device was evaluated. Given the random uncertainties derived from the numerous experimental measurements of the rut depth, statistical information was collected. Accordingly, the entropy maximum principle was used here to define adequate probability density function of the rut. Confidence regions with a high probability of 99% were determined for the estimation of the rut depth. In addition, comparison of mechanical and rheological results is performed with aged bitumen recovered from reclaimed asphalt and virgin bitumen to analyse the effect of ageing on bitumen viscoelastic properties. The experimental characterisation of the different binders based on rheological and conventional tests showed stiffening and hardening effects due to bitumen ageing.

Analysis by Differential Scanning Calorimetry of concrete modified with microencapsulated phase change materials

In this work, a thermal experimental investigation by Differential Scanning Calorimetry (DSC) of a Portland cement concrete modified with microencapsulated phase change materials labeled “PCM-concrete” is presented. First, the DSC technique was used for the thermal characterization of the micro-PCMs considered in this study. Accordingly, several thermal properties were determined such as the melting and freezing temperatures, the specific heat capacity and the change phase enthalpies. After, concrete mixtures with different PCM amounts were manufactured in laboratory and then the compressive strength was measured. Then, the PCM-concrete thermal performance was studied by DSC. Also, artificial accelerated ageing was performed on the PCM concrete mixtures in order to investigate the PCM stability in the concrete. Next, the thermal properties of the artificial aged PCM-concrete were determined by DSC and compared with the non-aged PCM concrete properties. Finally, the microstructure of the PCM concrete mixtures was analyzed by Scanning Electronic Microscopy (SEM) to check the PCMs state after their incorporation in the concrete. The results highlighted an improvement of the specific heat capacity of the PCM-concrete with the addition of PCMs. A slight loss of the mechanical strength was noted. Also, the thermal storage of PCM-concrete mixtures after the artificial ageing was enhanced with comparison with the reference non-aged one.