Abstrakt

The article presents Polish experience with cold recycling of asphalt pavements with theusage of bituminous emulsion and cement. In the 1990s numerous roads in Polandrequired immediate reinforcement due to their significant degradation. Implementation ofthe cold recycling technology was one of the solutions to this problem. Cold recycledmixtures containebeside the recycled asphalt pavement and aggregateetwo differenttypes of binding agents: bituminous emulsion and Portland cement. First Polish re-quirements were developed in the 1990s and were based on the Marshall test. After severalyears of application of these requirements, numerous transverse cracks appeared on thepavements. Field investigation showed that the frequency of transverse cracking was notuniform on all evaluated sections and that the growth rate of the number of cracks wasdecreasing. The main reason of extensive cracking was the overly high amount of thePortland cement and insufficient amount of the bituminous emulsion. This led to pro-duction of very stiff mixtures, with dominance of hydraulic bonds, which behaved simi-larly to cement-treated mixtures. The idea of flexible cold recycled base course was notutilized. This experience motivated the Polish Road Administration to develop new re-quirements. Second part of the article presents the new requirements for cold recycling.New test methods as well as requirements concerning resistance to frost and water actionwere introduced in 2013. Implementing of the new requirements resulted in significantreduction in stiffness of the MCE mixtures. Values of stiffness modulus are even threetimes lower, which should significantly decrease the amount of potential reflective crackson the pavement surface. Presently two types of technology of cold recycling are used in Poland, in-place and in-plant.

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