Abstract
The paper investigates the influence of redispersible polymer powder (RPP) on the physical and mechanical properties of a cold-recycled mixture with foamed bitumen (CRM-FB). Four types of RPP with a varied chemical base were used: VA-VeoVA, VA-VeoVa-Ac, EVA and VA/VV/E/Ac. The polymer powder-modified cold recycled mixture with foamed bitumen, (P)CRM-FB, was composed of 45.8% reclaimed asphalt pavement (RAP), 45.8% natural aggregate (VA), 3.0% Portland cement CEM I 42,5R, 3.0% foamed bitumen 50/70 and 3.0% RPP, all dosed by weight. The reference mixture, (R)CRM-FB, served as a reference point for comparison. It was found that RPP improved the workability of the CRM-FB mixture. This results in a reduced number of compaction cycles and lower energy needed to obtain the air void content as in the reference mixture. In addition, the RPP modifier markedly increased the CRM-FB mixture cohesion (ITSDRY) and strength, by approximately 40–70%, depending on the RPP used. These findings are particularly important for CRM-FB mixtures designed for road bases. The present investigations confirmed the improvement of the CRM-FB mixture parameters after the modification with RPP, regardless of the powder type used.
Highlights
Cold deep in place recycling is an established road rehabilitation solution used in Poland [1,2]and worldwide [3,4]
The skid resistance [6] is responsible for the safety of users, and the fatigue life of pavement layers depends on the type of binders [7,8,9], additives [10] and mineral components used, that is, aggregate [11] and reclaimed asphalt pavement (RAP) [12]
The main aims of the article are to explain how the CRM properties are modified by the addition of redispersible polymer powders (RPPs) and to confirm that the transfer of polymer properties to the CRM properties in terms of increased cohesion, increased elasticity of the mixture and increased ductility will reduce the risk of shrinkage cracks in road bases containing hydraulic binder
Summary
Cold deep in place recycling is an established road rehabilitation solution used in Poland [1,2]and worldwide [3,4]. Cold deep in place recycling is an established road rehabilitation solution used in Poland [1,2]. The durability and fatigue life of cold, half-warm [5] and hot mixture asphalt pavements depend on multiple factors. Common additives in cold deep recycled mixtures with foamed bitumen and bitumen emulsion include: cement, lime, ash (waste from cement production) [13] and hydraulic binders, which generally increase cohesion, durability, and in some cases improve the resistance to weather (moisture, interaction of moisture and frost). As demonstrated by the authors of [14], incorrectly designed cold-recycled mixtures may become excessively stiff, which leads to the formation of shrinkage cracks in the base course. Finding a solution to improve fatigue life without increasing the stiffness modulus of the cold-recycled mixture with foamed bitumen and cement seems critical
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