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The widespread use of natural aggregates is one of the main causes of the depletion of natural resources, as aggregates are constituents of several construction materials. Alternatively, it is, today, proven to be feasible to use mining tailings, either natural or recycled materials, to produce artificial aggregates through specific processes. A possible way to produce artificial aggregate is through the alkali activation of the powdered material in a process called geopolymerization. This study proposes to use a basalt powder and two different metakaolins as precursors for the production of an alkali-activated artificial aggregate, with a specific shape and size achieved by using 3D-printed molds. The experimental aggregates were evaluated using traditional tests for natural aggregates, such as resistance to compression, specific density and resistance to abrasion and fragmentation. Furthermore, the material was chemically analyzed in order to evaluate the geopolymerization process promoted by the two adopted metakaolins. The physical tests showed that artificial aggregates do not perform well in terms of resistance to wear and fragmentation, which can be improved. However, they revealed promising results in terms of skid, polishing and micro-texture.

As cities grow in size, traffic also increases, thus making the population more exposed to road noise and traffic accidents. It is therefore important to study and understand which properties of the pavement influence its acoustic impact and skid resistance performance. The pavement texture plays a major role in generating noise and friction, and it can be engineered in order to control both of them at the same time. The phenomena regulating skid resistance are well understood today. The same applies for noise generation and propagation; the literature contains methods of designing the pavement surface layer to achieve consistent results. Several types of solutions can be found for asphalt mixtures, most of them derived from decades of studies and research. They use different approaches to be effective for noise and friction, but all have in common the control of the surface’s macro and microtexture. Finally, some considerations are made regarding novel paving solutions with artificial aggregates instead of natural ones to address noise and skid resistance.

Cold bitumen emulsions (CBE) are currently used worldwide for both non-structural (cold surface treatments) and structural (cold bituminous mixtures) paving applications. Among non-structural applications, bituminous slurry surfacings (BSS) allow to improve surface properties and extend the pavement’s life. However, selection of constituents, mix design, application and quality control procedures for BSS are mostly based on local experience and empirical tests. Thus, the use of BSS is associated to higher technical risks with respect to the use of traditional hot-mix technologies. In this context the RILEM Technical Committee 280-CBE TG2 “Multiphase characterisation of cold bitumen emulsion materials” aims to collect worldwide theoretical knowledge and experiences on BSS and to inspire new standards, specifications and guidelines encompassing the wide set of existing practices. This paper summarizes the first part of the literature review carried out as part of the TC workplan and focuses on the definition, the description and the application method for BSS. National standards, construction specifications and best practice documents from North America, South America, Europe and Australia are analysed and compared.

O transporte rodoviário causa grande impacto no meio ambiente, tanto pelo grande consumo de energia quanto pela infra-estrutura física necessária a sua operação. A emissão de gases e os ruídos causados pelo tráfego causam danos irreversíveis ao meio ambiente e têm sido alvo de inúmeros estudos e pesquisas. Sabe-se que o atrito pneu/pavimento e as propriedades acústicas dos revestimentos influenciam de sobremaneira a geração e a propagação do ruído. Essa pesquisa tem como objetivo avaliar o ruído causado pelo tráfego de veículos em quatro diferentes pavimentos implantados em diferentes rodovias através do SPBI (Statistical Pass-By Index). A metodologia adotada seguiu as prescrições da norma ISO 11819-1, a qual determina que um decibelímetro seja instalado na lateral da via para medir o ruído máximo causado pela passagem de um veículo. O revestimento em CBUQ foi o pavimento cujas maiores medidas foram observadas (86,84dBA) seguido do CCP (83,28dBA), do TSD (83,26dBA) do MICRO (81,14dBA) e da CPA (81,03dBA). Os resultados indicam que a escolha adequada do revestimento pode atenuar de maneira expressiva o ruído causado pelo tráfego rodoviário. Highway transportation causes immense environmental impacts, as much by the enormous use of energy as for the physical infrastructure necessary for its operation. The gas emission and traffic noise cause irreversible damages to the environment and this has been the objective of a lot of studies and researches. It is known that the contact between tire and pavement surface and the acoustic properties of the coverings influence the noise’s generation and propagation. This research aims to evaluate the noise caused by the traffic of vehicles in four different pavements through SPBI (Statistical Pass-By Index). The methodology followed the prescriptions of the norm ISO 11819-1; the decibelimeter is installed in the road side and it records the maximum noise caused by each vehicle. HMA presents higher noise measurement (86,84dBA) followed by PCC (83,28dBA), ST (83,26dBA) MICRO (81,14dBA) and PC (81,03dBA). The results indicate that correct pavement selection can reduce, in an expressive way, the noise caused by road traffic.

The use of waste materials in road construction is becoming widely spread due to economic and environmental needs. Construction and demolition waste materials and mining residues have been studied for a long time. However, the use of fine materials, mainly from mine tailing and mining residue, is still complex, as they can be used as inert materials into the mix or can become a reactive agent in geopolymer mixes. In the present paper, an experimental application of basalt powder is proposed in the geopolymerisation reaction to produce artificial aggregates. In order to understand the input and output variables’ interactions used in the mix design, a statistical method called Design of Experiments was applied. With this design approach, it was possible to optimize the mix design of the experimental geopolymer mortars. The study evaluated several mixes with respect to their workability, compressive strength, and success rate of aggregates production. Finally, a model for predicting compressive strength is proposed and evaluated.