Assessment of the influence of the binder type on the stiffness modulus of mineral-cement-emulsion mixture (BE-RCM): Fid-Bau Portal

Assessment of the influence of the binder type on the stiffness modulus of mineral-cement-emulsion mixture (BE-RCM)

Krasowski, Jakub / Buczyński, Przemysław / Iwański, Marek

The subject of the research is to evaluate the influence of the composition and quantity of the hydraulic binder on the stiffness modulus of the recycled subbase, made of a mineral-cement-emulsion mixture (BE-RCM). Road subbases made in the technology of deep cold recycling are a proven method for the construction of the construction layer of the road surface. Among the many advantages, it is necessary to indicate the reuse of materials obtained during the demolition of a degraded pavement. There is also a real possibility of reducing the costs and time of reconstructing the road infrastructure. It is extremely important to choose the right hydraulic binder for the recycled mixture. The subbase must be a durable and load-bearing layer. It should be noted that the use of too much binder, in the form of Portland cement, may lead to the stiffening of the layer and the appearance of uncontrolled reflected cracks. Cracks of this type are initiated precisely in the hydraulically bound base layer. Currently, attempts are being made to modify the binder composition to avoid the occurrence of undesirable effects. The paper presents the results of research on the stiffness modulus of the recycled BE-RCM subbase depending on the measurement temperature and the composition of the hydraulic binder. Portland cement I class and a modifier in the form of a redispersible polymer powder with a polymer base (polyethylene-co-vinyl acetate) EVA were used as a binder. The impact analysis was performed using the assumptions of the Box-Behnken experiment plan in which three variables are controlled. The variables in the experiment were the content of: polymer, cement and asphalt emulsion in the mixture. The mentioned ingredients were dosed with a step of 1.5% of the percentage share in the mixture composition. EVA redispersible polymer powder and Portland cement were dosed from 0.5% to 3.5%. In contrast, the pure asphalt that came from the asphalt emulsion added to the mix was 0.0%, 1.5% and 3.0%, respectively. The obtained test results may be an impulse to optimize the binder composition of recycled cold mixes with asphalt emulsion. There is a chance to reduce the Portland cement content in BE-RCM mixes thanks to the use of a polymer modifier. The subbase made in this way has the appropriate parameters and values of the stiffness modules. The introduced polymer allows to reduce the occurrence of uncontrolled cracks in the foundation.