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Effects of zeolites and hydrated lime on volumetrics and moisture resistance of foamed warm mix asphalt concrete

Chomicz-Kowalska Anna, Maciejewski Krzysztof, Iwański Mateusz Marek, Janus Karolina

Bulletin of the Polish Academy of Sciences. Technical Sciences

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2021

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Vol. 69, nr 2

art. no. e136731

EN

The paper concerns the utilization of hydrated lime and zeolites as additives in warm mix asphalt produced with foamed bitumen. The mentioned additives were added to the mixtures in exchange for specific quantities of mineral filler, which amounted to 0.4% and 1.2% of hydrated lime or 0.4% of water-modified and 1.0% of air-dry zeolites in mineral mix. The study investigated warm-produced mixtures with 4.5% and 4.8% binder content and production and compaction temperatures set at 120⁰C and 100⁰C respectively. Additionally, reference hot and warm mixtures were evaluated. The testing included: air void content, indirect tensile strength in dry state and after one freeze-thaw cycle as well as the resulting resistance to moisture and frost damage index. The mixtures incorporating hydrated lime and lower bitumen content of 4.5% exhibited increased air voids and mostly unchanged mechanical performance when compared to the reference warm mix. Increased bitumen content has resulted in significantly improved performance in moisture resistance and compactability which could be compared to that of the reference hot-produced mixture. On the other hand, the incorporation of zeolites in the foamed bitumen mixtures resulted in all cases in increased air void content in the samples. This has apparently led to decreased indirect tensile strength, in both the dry state and after the freeze-thaw cycle. Based on the results it was concluded that the production temperature of the zeolite-bearing mixtures was too low for the zeolite water to significantly improve the mix’ workability and therefore positively affect its mechanical parameters.

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Laboratory testing of low temperature asphalt concrete produced in foamed bitumen technology with fiber reinforcement

Chomicz-Kowalska A.

Bulletin of the Polish Academy of Sciences. Technical Sciences

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2017

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Vol. 65, nr 6

779--790

EN

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.

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Moisture and frost resistance of the recycled base rehabilitated with the foamed bitumen technology

Iwański M., Chomicz-Kowalska A.

Archives of Civil Engineering

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2012

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Vol. 58, nr 2

185-198

EN

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.

PL

Ze względu na warunki klimatyczne wystepujące w krajach Europy Centralnej podbudowa powinna charakteryzować się wysokimi parametrami mechanicznymi oraz odpornością na działanie wody i mrozu. Przedmiotem badań była ocena właściwości recyklowanych mieszanek mineralnych z asfaltem spienionym w zależności od ilości zastosowanych materiałów wiążących (lepiszcza i spoiwa). Badania wykonano na mieszankach, w których wykorzystano materiał istniejących warstw konstrukcji nawierzchni drogowej. Zawartość lepiszcza asfaltowego wynosiła 2,0%, 2,5%, 3,0% i 3,5%, natomiast cementu 1,0%, 1,5%, 2,0%, 2,5%. Otrzymane wyniki badań poddane procesowi optymalizacji pozwoliły stwierdzić, że przy zastosowaniu 2,5% asfaltu spienionego oraz 2,0% cementu materiał podbudowy charakteryzuje się odpowiednimi właściwościami fizykomechanicznymi oraz wymaganą wodo- i mrozoodpornością wg. zastosowanych kryteriów.