A field and laboratory study was carried out to study the effect of pressure and temperature on the compaction of asphalt pavements. Density, temperature, number of passes, and type of roller were recorded in the field at four different paving projects in Wisconsin, with binder and mixture samples obtained from each project. Compaction in the field occurred at temperatures that ranged from 125 to 60°C . Densification was achieved only for temperatures above the 70–80°C range. Roller contact pressures were estimated between 300 and 700 kPa during the compaction process. Laboratory compaction was performed with Superpave gyratory compactor using the field compaction temperatures and contact pressures. The lab compaction results confirmed that below a certain temperature limit densification decreased significantly. Binder testing was performed to determine the binder viscosities in the full range of field compaction temperatures observed. The upper limit of viscosity for significant reduction in densificatio...

The present work deals with the influence of the nonlinear creep response of asphalt binders on asphalt mixture permanent deformation. Asphalt binders were tested using a Dynamic Shear Rheometer with cone and plate geometry. The mixtures were tested in unconfined compression using cylindrical samples. The resulting responses of binders and mixtures were fitted successfully using nonlinear power law models. Comparison of the fitted responses of the binders and mixtures indicated there is a strong correlation between the binder nonlinearity and the mixture nonlinearity. The degree of mixture nonlinearity is found to be highly defined by the binder nonlinearity, but it was also influenced by the aggregate gradation. The results highlight the importance of non-linear characterization of binders in studying permanent deformation of mixtures.

One of the relevant effects of anthropogenic climate change has been an anomalous increase in temperature near the earth’s surface. In the context of pavement engineering, materials that are thermally susceptible could be affected by these changes. For this reason, the possible effects of global warming in binder selection for asphalt pavements in Chile were studied. Two global warming scenario results obtained with MICRO5 model plus local downscaling with WRF model were used. The estimated temperature changes were calculated for the period 2030–2059 for the 94 weather stations previously used for the Chilean Superpave zonings. Three pavement temperatures models were used together with these new air temperature databases: SHRP, LTPP 2.1 and LTPP 3.1. The results were compared with the original Superpave zonings obtained with the same models. A significant number of stations underwent a change in PG grade for the period considered. Most of the predicted changes were increased in the high-temperature PG grade. The areas of use for the softer binder PG52-34 gradually decreased, while the areas for the stiffer PG64-22 increased. A new even stiffer binder PG70-16 had to be introduced into the new Superpave zonings.

This study aimed to determine an optimal dosage of sunflower oil (i.e., Virgin Cooking Oil, VCO) as a rejuvenator for asphalt self-healing purposes, evaluating its effect on the chemical (carbonyl, and sulfoxide functional groups), physical (penetration, softening point, and viscosity), and rheological (dynamic shear modulus, and phase angle) properties of long-term aged (LTA) bitumen. Five concentrations of sunflower oil (VCO) were used: 1%, 2%, 3%, 4%, and 5% vol. of LTA bitumen. VCO was encapsulated in alginate biopolymer under vibrating jet technology using three biopolymer:oil (B:O) mass ratios: 1:1, 1:5, and 1:9. The physical, thermal, and mechanical properties of the capsules were studied, as well as their effect on the physical properties of dense asphalt mixtures. The main results showed that an optimal VCO content of 4% vol. restored the chemical, physical, and rheological properties of LTA bitumen to a short-term ageing (STA) level. VCO capsules with B:O ratios of 1:5 presented good thermal and mechanical stability, with high encapsulation efficiency. Depending on the B:O ratio, the VCO capsule dosage to rejuvenate LTA bitumen and asphalt mixtures varied between 5.03–15.3% wt. and 0.24–0.74% wt., respectively. Finally, the capsule morphology significantly influenced the bulk density of the asphalt mixtures.

Three test sections of concrete pavements with short slabs were constructed between 2004 and 2006.The slab sizes ranged from 0.88 to 3.5 m. The thicknesses varied between 8 and 20 cm. The general performance of thinner slabs (8–10 cm) was poor. The thicker slabs (14 cm and above) showed promising results. The main distress observed in most cases was longitudinal cracking, followed by transverse and corner cracking. The test sections were used for calibrating a new mechanistic empirical pavement design method. The three cracking distresses observed in the field were included in the design method. Design examples are presented. The calculated slab thicknesses are compared with the thicknesses obtained for conventional rigid pavements. Important reductions in thicknesses are achieved as a result of using the shorter slabs.