Publicação
The importance of microsurfacing asphalt mix design in improving the performance of this cold surface treatment
| Resumo: | Cold asphalt mixtures are essential for surface treatments of road pavements and may be used as sustainable construction alternatives. Its popularity has been increasing due to its low impact on the environment and its consequent improved sustainability compared to hot paving technologies. In this context, the cold asphalt microsurfacing technique should be highlighted. It is a preventive maintenance technology that involves the application at room temperature of a modified emulsion, aggregates with an appropriate grading, filler (usually cement), water, and possible additives. Although it is a widely used technology, further studies on the mix-design procedures are necessary to ensure an adequate composition of the final mixture. This study proposed a new procedure for a microsurfacing mix design based on tests developed according to a set of European Standards for slurry surfacing. In the first step, two preliminary tests, developed by the RILEM TC-CBE-TG2, are carried out to determine the initial amount of cement and added water: the pizza test and the ball test. Subsequently, the consistency test (EN 12274-3) is performed to confirm the amount of added water in the mixture. Finally, the cohesion test (EN 12274-4) is performed to find the ideal relationship between the amount of added water, cement, and emulsion. In the end, the shaking abrasion test (EN 12274-7) was performed to determine the durability of the studied mixtures. The study used basalt aggregates, cement (filler), water, and two asphalt emulsions from Italy. Thus, for each test, two mixtures were produced: one with a C65BP4 emulsion and one with a C60BP4 emulsion. Also, in each test, the microsurfacing mixtures were always produced using the same aggregate and type of cement, varying the amounts of emulsion, added water, and cement. A sequence for adding each material was proposed to standardize the procedure of mixture production since there are no European standards for that. Thus, several trial mixtures with different compositions were prepared to study the ideal mix design, constantly repeating the tests and changing the amount of each material under study to reach the expected results. The design of these microsurfacing mixtures was influenced by the emulsion type, with an ideal ratio between the amount of asphalt emulsion, water, and cement. Therefore, the design of microsurfacing mixtures is a complex task within a system with chemical interactions strongly influenced by the composition of the materials used in the mixtures. It was concluded that the sequence and tests proposed for designing the microsurfacing mixture are essential to achieve the ideal amounts of asphalt emulsion, additional water, and cement. However, more research is needed to understand the relationship between these materials and improve the performance of microsurfacing mixtures. |
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| Autores principais: | Moura, Caroline Fernandes Nunes |
| Outros Autores: | Palha, Carlos Alberto Oliveira Fernandes; Oliveira, Joel R. M.; Silva, Hugo M. R. D. |
| Assunto: | Microsurfacing mix design Cold surface performance Engenharia e Tecnologia::Engenharia Civil Indústria, inovação e infraestruturas |
| Ano: | 2023 |
| País: | Portugal |
| Tipo de documento: | outro |
| Tipo de acesso: | acesso restrito |
| Instituição associada: | Universidade do Minho |
| Idioma: | inglês |
| Origem: | RepositóriUM - Universidade do Minho |
| Resumo: | Cold asphalt mixtures are essential for surface treatments of road pavements and may be used as sustainable construction alternatives. Its popularity has been increasing due to its low impact on the environment and its consequent improved sustainability compared to hot paving technologies. In this context, the cold asphalt microsurfacing technique should be highlighted. It is a preventive maintenance technology that involves the application at room temperature of a modified emulsion, aggregates with an appropriate grading, filler (usually cement), water, and possible additives. Although it is a widely used technology, further studies on the mix-design procedures are necessary to ensure an adequate composition of the final mixture. This study proposed a new procedure for a microsurfacing mix design based on tests developed according to a set of European Standards for slurry surfacing. In the first step, two preliminary tests, developed by the RILEM TC-CBE-TG2, are carried out to determine the initial amount of cement and added water: the pizza test and the ball test. Subsequently, the consistency test (EN 12274-3) is performed to confirm the amount of added water in the mixture. Finally, the cohesion test (EN 12274-4) is performed to find the ideal relationship between the amount of added water, cement, and emulsion. In the end, the shaking abrasion test (EN 12274-7) was performed to determine the durability of the studied mixtures. The study used basalt aggregates, cement (filler), water, and two asphalt emulsions from Italy. Thus, for each test, two mixtures were produced: one with a C65BP4 emulsion and one with a C60BP4 emulsion. Also, in each test, the microsurfacing mixtures were always produced using the same aggregate and type of cement, varying the amounts of emulsion, added water, and cement. A sequence for adding each material was proposed to standardize the procedure of mixture production since there are no European standards for that. Thus, several trial mixtures with different compositions were prepared to study the ideal mix design, constantly repeating the tests and changing the amount of each material under study to reach the expected results. The design of these microsurfacing mixtures was influenced by the emulsion type, with an ideal ratio between the amount of asphalt emulsion, water, and cement. Therefore, the design of microsurfacing mixtures is a complex task within a system with chemical interactions strongly influenced by the composition of the materials used in the mixtures. It was concluded that the sequence and tests proposed for designing the microsurfacing mixture are essential to achieve the ideal amounts of asphalt emulsion, additional water, and cement. However, more research is needed to understand the relationship between these materials and improve the performance of microsurfacing mixtures. |
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