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  • Author: A. Chomicz-Kowalska x
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A. Chomicz-Kowalska

Abstract

The paper presents the design process and test results of warm mix asphalt concrete produced with modified foamed bitumen and recycled synthetic fiber reinforcement. Recycling and low-temperature asphalt production techniques are now seen as the possibilities to increase the sustainability and energy effectiveness of road construction. Although low processing temperatures permit increased use of reclaimed and recycled materials in new asphalt mixes, they sometimes result in impaired service performance. The aim of this article was to present a possibility of producing a better performing asphalt concrete (in comparison to a control hot-mix) at lower temperatures. For this purpose two road paving bitumens modified with a surface active agent and a Fischer-Tropsch wax thoroughly tested for their basic, rheological characteristics and foaming performance. Selected binders were used for producing two control mixes (hot-mix and foamed warm mix with 35/50 bitumen) as well as the experimental mix with the modified 50/70 bitumen and an addition of synthetic fiber material from recycling of automotive tires. Basic properties of the mixes were tested (air void content, moisture susceptibility with one freeze-thaw cycle, wheel tracking) along with stiffness moduli and fatigue resistance. It was concluded that the control foamed warm-mix performed significantly worse than the hot-mix, while the experimental warm-mix with modified bitumen and fiber additive exhibited increased performance and resistance to fatigue and moisture.

Open access

M. Iwański and A. Chomicz-Kowalska

Abstract

This paper focuses on evaluation of two laboratory-based methods of compaction of foamed bitumen and bitumen emulsion mixes: impact compaction with a Marshall hammer and static compaction using a hydraulic press. The investigated compaction methods were assessed in terms of their impact on the physical and mechanical properties of produced laboratory specimens, including: air void content, indirect tensile strength before and after conditioning in water (ITSdry, ITSwet), tensile strength ratio (TSR), and indirect tensile stiffness modulus (ITSM) at 0°C, 10°C and 20°C. The statically compacted specimens attained higher levels of mechanical properties and resistance to moisture damage, which was associated with a lower content of air voids in the specimens formed using a hydraulic press. Authors present a calculation showing that a mechanistic design based on the laboratory static press compaction method leads to overestimation of fatigue cracking resistance of the road base.

Open access

M. Iwanski and A. Chomicz-Kowalska

Abstract

The technology of recycling with foamed bitumen is a new technology of road rehabilitation. Due to the climatic conditions in the Central European countries, road pavement structure should be moisture and frost resistant. Because of its specific production conditions, this is especially important for pavements rehabilitation with the cold recycling technology. Determining the physical and mechanical properties, as well as moisture and frost resistance, depends on binder and filler contents. They are the key elements before its use for road building. The tests presented here have been performed on mineral recycled base mixes with foamed bitumen. The material from the existing layers was used. The content of bitumen binder amounted to 2.0%, 2.5%, 3.0% and 3.5%, while that of cement to 1.0%, 1.5%, 2.0%, 2.5%. The results were subject to the optimization process. This allowed to state that with the use of 2.5% foamed bitumen and 2.0% of cement, the base had the required properties, as well as the moisture and frost resistance.