Search

This paper presents the results of a research study whose main objective was to analyze the environmental benefits derived from a cleaner production technology for manufacturing asphalt mixes. This study measured polluting emissions during the construction of two consecutive stretches of highway on which a hot mix and a half-warm mix were spread. Combustion gases (CO, NO x , O 2 , CO 2 ), total organic carbon (TOC), particles, volatile organic compounds (VOCs), and polycyclic aromatic hydrocarbons (PAHs), were measured during the manufacturing of hot and half-warm asphalt in plant and also during the spreading and compaction processes. The results obtained in this research project show that for the same manufacturing and spreading conditions, the half-warm mix asphalt (manufactured at less than 100 °C) is a cleaner production technology and can be considered more environmentally friendly since it considerably reduced polluting emissions.

The cold in-place recycling (CIR) of asphalt pavements is a technique for pavement rehabilitation that uses 100% of the milled or reclaimed asphalt pavement (RAP) from a deteriorated road surface at ambient temperature, and which does not heat any of the mix components. Consequently, CIR has the advantage of reducing gas emissions into the atmosphere. It also cuts fuel consumption since there is no need to transport RAP to an asphalt plant or to convey the mix from the plant to the paving site for spreading and compaction. Nevertheless, one of the weaknesses of this technique is the design of the job mix formula since the densities of laboratory test specimens are generally higher than the densities of the samples obtained at the worksite. As a solution for this problem, we designed an in-laboratory compaction procedure capable of manufacturing test specimens, whose density closely approximated the density of the material at the worksite. For the purposes of our research, we selected three CIR roadwork projects carried out in 2009 in southern Spain. These sites provided the RAP and the emulsion for the laboratory work in our study. It was thus possible to validate the compaction method designed in our research by comparing the dynamic modulus values of pavement cores extracted at the worksite with the values of cores taken from the laboratory specimens. The results obtained validate the new compaction procedure designed in this study.

The concept of sustainability has become crucial in today’s world. In fact, one of the major environmental priorities in scientific research is to discover innovative ways to recycle waste matter for its use in activities that benefit society. In the construction engineering sector, this trend has led to new techniques for recovering waste from industrial processes, and using it as a replacement for raw materials. The Construction Engineering Laboratory at the University of Granada carried out a research project to study the viability of using waste from the decorative quartz industry (sludge and chips from stone sheets) in the manufacture of bituminous mixes for road surfacing. This research study was performed in two phases. The first phase analyzed scraps and chips from stone sheets to see if they could be used to replace natural aggregate. The second phase focused on evaluating Silestone® sludge to see if it could be used as a substitute for the filler fraction in hot bituminous mixes. This paper presents the results obtained in this second phase in which different job-mix formulas were evaluated by varying their sludge content (0%, 60% and 100%). The properties of the various mixes were analyzed by subjecting them to a battery of mechanical tests that determined their susceptibility to moisture and resistance to rutting. The results obtained are eloquent proof of the viability of reusing Silestone® sludge as a replacement for conventional filler. This study showed that when performance of such mixes was tested, they amply fulfilled the standard technical requirements for roads in Spain. Furthermore, it was found that the job mixes with sludge had a significantly better performance than the standard F10 mix that did not contain it.

One of the most common road pavement pathologies is caused by water action. The presence of moisture causes a reduction in aggregate-binder adhesion in the mix as well as in the internal cohesion of the bitumen. This leads to problems such as pot holes, aggregate peeling, stripping, etc., which eventually lead to the structural failure of the pavement. Currently, there are numerous laboratory tests that analyze the susceptibility of bituminous mixes to moisture, providing a qualitative or quantitative evaluation. This study analyzes the performance of bituminous mixes in different experimental conditions. For this purpose, a comparative study of two laboratory tests was carried out. The tests differed in mix compaction method, the conditioning of the test specimens, and the type of load applied. The results obtained showed that in these tests the conditioning temperature had a greater impact on mix performance than the temporal duration of the conditioning process. Furthermore, the application of tensile stress was found to be more suitable for studying moisture susceptibility since mixes were found to be more sensitive to this type of load.