Piergiorgio Tataranni

Effects on Bonding of Anti-reflective Cracking Solutions at the Top Bituminous Interface of a Small Airport Pavement: A Laboratory and Modeling Study

The maintenance of bituminous airport pavements is of high concern when the limited available time for interventions and the performance effectiveness of the adopted materials are considered. In many cases, due to their former military vocation, small airport pavements have robust, sound and durable foundations that seldom require deep interventions of maintenance. Thus, it is more often needed to rehabilitate the pavement bituminous surface layers to restore the functional characteristics of the runaway and to protect the bottom layers from water leaching through the surface damages (e.g. cracks). This paper shows an example of airport pavement maintenance that was designed to rehabilitate the wearing course of a cracked bituminous structure that was proven to have sufficient bearing capacity. In order to prevent the reflection of cracks on the new layer, the effects of using both a geosynthetic net and a Stress Absorbing Membrane Interlayer (SAMI) were investigated at the old-new materials interface. The effects of debonding and the potential risk of slippage or delamination of the new wearing course were assessed by means of laboratory direct shear tests and multilayer elastic pavement system modeling.

Preliminary Research on the Physical and Mechanical Properties of Alternative Lightweight Aggregates Produced by Alkali-Activation of Waste Powders

There is growing interest in construction field issues related to environmental protection, energy saving and raw materials. Therefore, the interest in recycling waste materials to produce new construction ones is constantly increasing. This study proposes a new methodology to produce lightweight aggregates (LWAs) by alkali-activation of two different waste powders: a digested spent bentonite clay and a basalt powder. Metakaolin, as secondary precursor, was added to the mixtures according to mix-design proportions, to improve the mechanical properties of the final materials, while a specific activators mix of Sodium Silicate and Sodium Hydroxide enabled the alkali-activation. The expansion process, on the other hand, was obtained using Peroxide within the liquid mix. The experimental LWAs were analyzed and tested in compliance with the EN 13055-1 standard. A more in-depth analysis on LWAs’ air voids content and porosity was also carried out by the means of Mercury Intrusion Porosimetry and Nuclear Magnetic Resonance. The results were compared with those obtained from commercial Lightweight Expanded Clay Aggregate, which represents one of the most common LWAs in the construction field. According to the presented preliminary results, the use of alkali-activated waste powders seems to be a suitable solution for the production of eco-friendly LWAs by allowing the recycling of waste materials and energy saving for their production.

Mechanical and Thermal Performance of Macro-Encapsulated Phase Change Materials for Pavement Application

Macro-encapsulated phase change material (PCM) lightweight aggregates (ME-LWA) were produced and evaluated for their mechanical and thermal properties in road engineering applications. The ME-LWAs were first characterised in terms of their physical and geometrical properties. Then, the ME-LWAs were investigated in detail by applying the European Standards of testing for the Bulk Crushing Test and the Polished Stone Value (PSV) coefficient as well as Micro-Deval and laboratory profilometry. In addition, the thermal performance for possible construction of smart pavements with the inclusion of ME-LWAs for anti-ice purposes was determined. The crushing resistance of the ME-LWAs was improved, while their resistance to polishing was reduced. Thermal analysis of the encapsulated PCM determined it to possess excellent thermal stability and a heat storage capacity of 30.43 J/g. Based on the research findings, the inclusion of ME-LWAs in surface pavement layers could be considered a viable solution for the control of surface temperatures in cold climates. Road safety and maintenance could benefit in terms of reduced ice periods and reduced treatments with salts and other anti-ice solutions.

Reuse of mining waste into innovative alkali-activated-based materials for road pavement applications

Based on the initial results obtained in the research program REMINE (H2020 RISE-Marie Curie Action) in progress, authors discuss the potential use of Panasqueira mine waste aggregates and fillers in the production of construction materials for transportation infrastructures. An estimate of the economic and social impact that this form of recycling could have on the local communities and on the perspective of other mining activities in Portugal and Europe is given. The main goals of the project are to explore materials design methods of alkali-activated composites from mining/quarrying wastes based on the demanding requirement of rheology to fit for various processing techniques and applications. The development of artificial aggregates through alkali-activation of mining waste presents itself as a viable technical solution to compete with other commonly adopted materials and may lead to the manufacturing of less porous and harder aggregates for the production of most of the road paving materials. 1 SOCIAL, ECONOMIC AND ENVIRONMENTAL IMPACT OF MINING ACTIVITIES 1.1 Panasqueira mine and its ores Panasqueira is one of the oldest underground mines in Portugal. The mine has been active for over 125 years. Panasqueira contains one of the largest economic viable tungsten vein deposits in the world. The tungsten is the main product of exploitation of Panasqueira. The mine is today operated by Sojitz Beralt Tin & Wolfram (Portugal) SA. The ore deposits consist of a series of stacked, sub-horizontal, hydrothermal quartz veins that lead into mineralized wolfram-bearing schists and shales (Cavey & Gunning, 2006). The mineralized zone has dimensions of approximately 2,500 m in length, varying in width from 400 m to 2,200 m, and continues to at least 500 m in depth. Wolframite, cassiterite and chalcopyrite are the extracted minerals obtained. Such minerals are treated to make concentrates of tungsten, tin and copper, respectively. The current extraction methodology is a mechanized room-and-pillar method, based on an analysis of geological and geomechanical characteristics of the rock mass. The ore treatment process begins with heavy media separation for the coarse fractions of material. It enables removing about 80% of the ore that has no tungsten content. Afterwards, this pre-concentrated material is subjected to a conventional gravity concentration method, followed by sulphide removal using flotation and final dry magnetic separation (Franco et al., 2014). Until 1996, the pre-concentrates were transported to the Rio plant, but today, the final separation procedures are carried out exclusively in the Barroca Grande plant. A huge tailings