António Correia Diogo

Chemical and Thermal Characterization of Road Bitumen Ageing

Bitumen ageing stands for a number of physico-chemical modifications that occur in bitumen as a response to environmental conditions. Several tests have been proposed to simulate bitumen ageing. Two of the most common ones are: a) the Rolling Thin Film Oven Test (RTFOT), which simulates short term ageing; b) the Pressure Ageing Vessel (PAV) test, which accounts for long-term ageing and it is usually performed on the RTFOT residue. A study of the physico-chemical modifications of a 50/70 pavement grade bitumen caused by ageing is presented. Both RTFOT and PAV tests were used. A follow-up of bitumen modifications due to ageing was done by several methods. In particular: 1) Fourier transform infrared spectroscopy (FTIR), to follow bitumen oxidation by the increase of oxygenated functional groups, which were quantified by taking appropriate structural indices; 2) Iatroscan thin layer chromatography (TLC), to follow bitumen composition expressed by the generic SARA fractions (saturates, aromatics, resins and asphaltenes); 3) Gel permeation chromatography (GPC), under “ultra-fast” conditions, to follow the colloidal structure of bitumen; and 4) Differential scanning calorimetry (DSC), to evaluate the changes of the crystallized fractions (%FC) and the glass relaxation temperature (Tg). The results show that the PAV test causes more severe changes in bitumen than the RTFOT test. In particular, the evolution of the oxidation processes could be quantified by taking carbonyl and sulfoxide structural indices. Ageing also modified the SARA profile, namely, the relative contribution of aromatics, resins and asphaltenes fractions. On the other hand, DSC data remained almost unaffected after ageing tests, which may be indicative of the survival of most of the phases of the bitumen after these tests. Finally, a comparative analysis of the sensitivity and performance of all these methods is presented.

Comparison of Young’s Moduli of Engineered Stones Using Different Test Methods

This work reports the results of Young’s modulus of elasticity obtained for 3 types of engineered stones. Using parallelepiped specimens with dimensions 150  30  20 mm3, Young’s modulus is determined by different methods: static and dynamic. Via quasi-static deformation tests: - uniaxial tension, - uniaxial compression, and, - pure bending (i.e. symmetrical four-point bending), determination of Young’s modulus was carried out by means of the conventional electric-resistance extensometry with strain-gauge strips glued to the specimens. The results obtained from these quasi-static deformation tests are compared with the results of dynamic Young’s modulus obtained with RFDA equipment (Resonant Frequency & Damping Analyser) using the parallelepiped specimens in a flexural vibration mode. Dynamic Young’s modulus was also evaluated through measurements of ultrasonic pulses velocity. Composition and microstructures of the materials under investigation are also presented and discussed.

Bituminous Binders and Mixtures

The subject of this chapter is to present materials for construction and civil engineering that incorporate bitumen and bituminous binders in its composition to be used in waterproofing systems and pavements of transport infrastructures, e.g. roads and airfields. General properties of bitumen, bitumen binders and bitumen emulsions are described. Waterproofing systems and bituminous mixtures are the main materials regarding the use of bitumen and bituminous binders for main civil engineering purposes. In the case of bituminous mixtures, the composition, properties and main products and applications are presented in the perspective of their use in pavement layers. Surface treatments and other special products and applications are also included. The main technical requirements are related to the materials, techniques and equipments involved during the design, construction, maintenance, rehabilitation and recycling of these bituminous materials.

Bitumen Morphology as Observed by Phase-Detection Atomic Force Microscopy

An analysis of the microstructure of several modified bitumen shown by phase detection Atomic Force Microscopy (AFM) is presented here. The phase detection and topographic AFM images, displayed three different types of microstructure: the so-called catana phase domains (beelike structures) dispersed in the peri-phase are present in most of the cases; para-phase domains are also observed in the neighbourhood of both catana and peri-phases. These results are consistent with the picture of bitumen as a heterogeneous mixture, as one should expect. The proportions of all these phases display a rather strong dependence on the nature of the modified bitumen considered, on the concentration of the modifier, as well as on the amount of aging of the mix.

Characterisation of the Filter Elements of End-of-Life Biological and Chemical Protection Masks Used by the Army

The main purpose of the present study is to assess the usefulness of filter cartridges from end-of-life biological and chemical protection masks, for other applications (with increased added value) instead of landfill deposition. Filters with different ages up to fifty years, were dismantled and divided in their components. Physico-chemical characterisation of each filter cartridge component was performed using different techniques such as: optical microscopy, Fourier transform infrared spectroscopy, pyrolysis, particle size distribution by laser diffraction, surface area determination from the nitrogen adsorption isotherms at 77K, determination of open porosity by helium pycnometry, and dynamic mechanical thermal analysis in the temperature range from -100°C to 200°C. It is shown that the loss of resilience of the rubber sealant is the main factor that controls the shelf life of filter cartridges. On the other hand, most of the charcoal in the activated carbon cloth remains active and can be useful for other less severe applications such as the removal of dissolved components from freshwater and/or marine systems.