The interest in minimising fuel consumption and greenhouse gas emissions among road specialists is increasing. Thus, methods for reducing asphalt concrete mixing and compaction temperatures by a few tens of degrees Celsius without compromising the long-term performance has become a topic of significant interest. This study is focused on the analysis of warm mix asphalt (WMA) prepared with locally available materials in order to determine the suitable technology applicable to the specific traffic and climatic conditions of Romania. WMA was prepared using different warm mix additives (organic additives, chemical additive, and synthetic zeolite) at different mixing and compaction temperatures, and bitumen blends with these additives were analysed by carrying out the dynamic shear rheometer test and evaluating the penetration index. In conclusion it was noted that most additives did not lead to a significant change of bitumen`s characteristics, but the organic additive had a big influence on the bitumen`s properties. The characteristics of WMA are very similar to those of HMA. The mixing and compaction temperatures could be reduced by approximately 40 °C when WMA was blended with the additives without compromising the performance of the asphalt mixture, compared to hot mix asphalt.

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Within the last decade, much attention has been focused on determining viable techniques for producing sustainable asphalt mixtures and minimizing fuel use and greenhouse gas emissions. Thus, warm mix asphalt (WMA) has become a topic of significant interest among road specialists as it offers a potential solution for reducing the environmental impact of the asphalt mixtures due to the decreased temperatures they require for mixing and compaction compared to hot mix asphalt (HMA). The present study is focused on the Life Cycle Assessment (LCA), according to a “Cradle-to-Gate” approach, of hot mix asphalt and warm mix asphalt prepared with locally available materials and different warm mix additives such as organic additives, chemical additive, and synthetic zeolite. For the analysis of the environmental impact of the warm mix asphalts was used a dedicated software for modeling and evaluating the LCA. The WMA prepared with chemical additive or organic additive led to a decrease of the environmental impact, in the production phase, compared to HMA. The study reveals that the raw materials extraction has the greatest impact on the environment in all studied cases, followed by the actual production phase of the asphalt mixture. For WMA produced with additives there was a decrease in the global impact on the environment compared to HMA.

The paper presents studies and laboratory tests concerning the influence of the way the natural quarry aggregates are processed upon the composition of an asphaltic concrete with a maximum grain size of 16 mm (BA 16). The research included the realization of grading curves on certain aggregates, curves lately compared to the maximum density line. This approach aims at classifying certain aspects concerning some of the physical-mechanical characteristics of the asphalt concretes determined through static and dynamic laboratory tests. The research resulted from the fact that in Romania, the elementary gradings on granular fractions from the same source, entering the composition of a certain asphalt mix, differ most of the times depending on the manipulation and the processing manner, respectively. This finding is based on the experience of the laboratory testing, where different values concerning the volume weight, apparent volume weight, voids and rigidity module were obtained on the same asphalt mix dosage prepared according to the prescription in two separate samples.Thus, in order to emphasize the impact of the processing manner (crushing) of the natural aggregates, the authors determined the percentage distribution on intermediate granular fractions of the gradings entering the composition of an asphalt concrete. Since the Romanian Standard for asphalt mixtures stipulates a large grading envelope between the standard sizes corresponding to each grading, the authors considered that there is no uniform distribution ratio depending on the size of the grains entering its composition. The study started from different research methods found in the specialized literature dealing with the calibration of the optimal grading curve. The results of the laboratory tests performed on the asphalt mixture confirm the importance of the particle size analysis in obtaining high quality physical-mechanical characteristics.

In recent years, due to the advent of several additives and innovations, asphalt mix design has become more complex. The mixes meeting the volumetric mix design requirements may still fail prematurely in the field. Thus, a transition from a simplistic volumetric-based mix design to a performance-based mix design is required, which was also envisioned in the Strategic Highway Research Program (SHRP) and Superpave mix design. In addition to performance verification, asphalt mix designs should also be evaluated for the life-cycle costs and environmental impact to encourage durable as well as sustainable and cost-effective alternatives. In this study, three asphalt mixtures with different reclaimed asphalt pavement (RAP) contents and additives were evaluated for cracking and rutting performance by using different performance thresholds for asphalt mixtures that are generally used in the construction of high-volume roads in Oregon. A balanced mix design process was followed to determine the required binder content for the three mixtures. Based on the life cycle cost and environmental impact analyses, the mixture with warm mix additive (WMA) was selected as the most economically and environmentally viable asphalt mixture to be used for construction in Oregon.