Giovanni Giacomello

Effect of Warm Mix Chemical Additives on the Binder-Aggregate Bond Strength and High-Service Temperature Performance of Asphalt Mixes Containing Electric Arc Furnace Steel Slag

Warm Mix Asphalt (WMA) is a modified asphalt concrete, obtained by using organic, chemical or foaming additives, which can be produced and compacted at lower temperatures (100–140 °C). The environmental sustainability of WMA can be enhanced with the inclusion of steel slag in substitution of natural aggregates. Given this background, this paper illustrates an experimental research aimed at characterizing WMA containing steel slag. Rheological tests were carried out on asphalt binders in order to investigate the effect of the WMA additive on high-service temperature properties. Then, the bond strength between asphalt binders and aggregates (limestone and steel slag) was investigated. Finally, compactability and permanent deformation resistance of the studied mixtures were also evaluated. Results mainly showed that, regardless the presence of steel slag, the studied additive allowed adequate mixing and compaction at lower temperatures, improving the bond strength between binder and aggregates without affecting permanent deformation resistance of asphalt mixes.

Experimental Analysis of Waterproofing Polymeric Pavements for Concrete Bridge Decks

ABSTRACT On concrete bridge and viaduct decks, traditional bituminous pavements are often subject to rapid degradation, particularly due to precipitation, traffic loadings and chemical attack. Pavement failure can also be due to underlying cracks related to steel reinforcement corrosion. For this reason waterproofing plays an important role in durability of the structure. Waterproofing can be done by means of polymeric binders and aggregates, mixed or applied together in the surface course. The paper summarizes the main results of a study aimed at mechanically characterizing resin-aggregate mixtures (premixed and multi-layers) for bridge waterproofing and paving: two types of resins and several types of natural and artificial/industrial aggregate (EAF slag, C&D aggregate, limestone and quartz sand) were used. Permanent deformation resistance and adhesion tests were conducted, as well as trials to define the surface characteristics of the product (skid resistance, permeability, macro-texture). The comparison demonstrates that polymeric slurries present better resistance than polymeric multi-layers and bituminous mixtures to permanent deformation at higher temperatures (40 to 60 °C), but show some deficiencies in adhesion properties. However, the surface characteristics of polymeric multi-layers are preferable to those of slurries and traditional bituminous mixtures.

A Rheological Study on Rejuvenated Binder Containing Very High Content of Aged Bitumen

Hot recycling of reclaimed asphalt pavement (RAP) coming from flexible pavement rehabilitation is a technique able to ensure real economic and environmental benefits related to the reduction of virgin bitumen and aggregate supply and to the reuse of a recycled aggregate. Otherwise, adequate performance of recycled materials with high amount of RAP must be guaranteed since the recycling involves the presence of old and stiffened aged binders within the mixture. In this perspective, the present experimental study was aimed at verifying in the laboratory the performance at mid and high-service temperatures of bituminous blends composed by 40% of virgin binder and 60% of old rejuvenated bitumen (simulating aged bitumen coming from RAP). Rheological properties of materials were studied through the dynamic shear rheometer, testing unaged, short-term aged and long-term aged samples. Viscosity, stiffness and permanent deformation resistance of recycled blends seemed to guarantee comparable behavior with those of original bitumens, regardless the aging condition of the materials. These findings seemed to demonstrate the effectiveness of the hot recycling procedure using rejuvenators to obtain suitable bituminous binder containing high amount of aged bitumen.

Life-cycle assessment of road pavements containing marginal materials: Comparative analysis based on a real case study

The Life-Cycle Assessment (LCA) is a standardized procedure generally used, in Italy, in industrial engineering to evaluate the economic-environmental efficiency of production processes. LCA is aimed at optimizing the design, with special emphasis on environmental sustainability. Also in the construction sector, LCA has recently gained a fundamental role as a quantitative measurement tool able to take into account correctly the environmental and economic benefits achievable adopting different alternatives (most of them uncommon) based on the entire service life, maintenance and end-of-life procedures included. As far as pavement engineering is concerned, the use of marginal materials (such as, for example, reclaimed asphalt pavement, crumb rubber, slags, etc.) is becoming of strategic importance due to the decreasing availability of virgin natural resources and the consequent increasing public consciousness addressed to environmental protection and preservation. In this regard, the LCA applied to road pavements constructed using marginal aggregates probably represents the only effective tool able to evidence the crucial aspects on which the design choices should be based, taking also into account longterm parameters. Given this background, the present research illustrates one real case study of LCA analysis applied to asphalt pavements of a motorway. The use of industrial by-products (i.e. steel slags) instead of natural mineral aggregates is considered. Comparative evaluation of different scenarios has been carried out using specifically developed spreadsheets. The research study demonstrates that LCA is able to highlight potentialities and issues related to the different analyzed scenarios, representing a valid tool for designers and decision-makers. Moreover, the obtained results contribute to enlarge the worldwide database about the implementation of LCA for pavements. 1.2 The standards for LCA methodology Life Cycle Assessment is defined and described in ISO 14040 and ISO 14044 (ISO 2006a, b) standards. LCA framework (Fig. 1) can be divided in the following steps: 1) goal and scope definitions; 2) inventory collection and analysis; 3) environmental impact assessment; 4) obtained results interpretation. ISO standards describe in detail principles, framework, requirements and guidelines for the LCA, including: a) the goal and scope definition of the LCA; b) the life cycle inventory analysis (LCI) phase; c) the life cycle impact assessment (LCIA) phase; d) the life cycle interpretation phase; e) reporting and critical review of the LCA; f) limitations of the LCA; g) relationship between the LCA phases; h) conditions for use of value choices and optional elements. However, these standards do not state specific prescriptions to perform a LCA or defined methodologies for the specific LCA phase. Further, LCI phase can be performed separately from a specific LCA study, because LCI inputs/outputs introduction and quantification are not closely linked with the specific product or service evaluated with the LCA. Figure 1. Life Cycle Assessment framework (from the ISO 14040 (ISO 2006b)). 1.3 LCA in road engineering The attention addressed to the minimization of impacts related to the construction inclusion in the environment defines a general trend concerning the study of ecological characteristics throughout the different infrastructure project hypothesis (from design to maintenance, from use to end-oflife). LCA can be applied to several civil engineering sectors, such as the transport infrastructure one. In this sense, many researchers already ventured in LCA implementation to evaluate the environmental impacts connected to transport infrastructures, facing the most important problems related to the material type and its transport, that strongly represent onerous items in road construction and maintenance (Jullien et al. 2009, Santero et al. 2011, Azarijafari et al. 2016). The increasing expensiveness of road design (in terms of energy request and environmental impacts) involves the need to reduce work emissions and costs during its lifetime. In this sense, even more researchers, management and construction companies develop sustainable project and utilize LCA in decision procedures which affect several environmental aspects (such as impacts of different pavement types and materials). Also the decision-makers, with an accurate life cycle cost analysis, can use LCA to evaluate the project or policy impacts (Santero et al. 2011). Many studies evaluate the environmental issues and the effects on road construction, management/maintenance and rehabilitation. Amini et al. (2012) compared conventional and perpetual pavement (i.e. not requesting structural maintenance) and their different effects on environment and costs. Others researchers suggested to take into account the effect on the environment and infrastructure caused by road traffic (Zaabar & Chatti 2010, Santos et al. 2015a). For example, Bryce et al. (2014) evaluated through LCA the possibility to reduce the road maintenance activities considering the pavement damage and the related tire vehicles consumption (the surface type affects the vehicles pollution). Yang et al. (2015) assessed the use of Reclaimed Asphalt Pavement – RAP and Recycled Asphalt Shingle – RAS in partial substitution of virgin aggregates to check the different environmental impacts, considering also the vehicles fuel consumes as a function of the IRI index. Others authors studied LCA applied to road infrastructure materials. DeDene & Marasteanu (2012) examined the possibility to reduce production costs and harmful emissions of asphalt pavement with 15% of RAP. Butt et al. (2014) applied LCA to bituminous mixtures assessing the energy consumption and the environmental sustainability. In this case, the analysis of significant 1 Goal and scope definition 2 Life Cycle Inventory analysis (LCI) 3 Life Cycle Impact Assessment