Minimum and maximum void ratios in tyre-derived and recycled concrete aggregate mixtures

Publication Title
Minimum and maximum void ratios in tyre-derived and recycled concrete aggregate mixtures

Abstract

Scrap tyre rubber is considered an appropriate material for use in geotechnical seismic isolation systems due to its beneficial dynamic properties, low unit weight, and sustainability. Rubber particles are commonly mixed with sand or gravel to reduce compressibility and increase shear strength. Such mixtures are typically prepared to a prescribed relative density, which necessitates the reliable determination of the minimum and maximum void ratios (e_min and e_max). This paper presents the e_min and e_max values obtained for mixtures of well-graded rubber granulate and well-graded recycled concrete aggregate, with the rubber content by weight X_M = 0, 11, 23, 55, or 100%. The investigation showed that vibration, recommended in standard procedures to determine e_min, was effective for RCA and RCA-TDA mixtures, but gave overestimated values for TDA. The method using a measuring cylinder proved to be the most effective for determining e_max. The relationships between X_M and e_min or e_max showed trends similar to those for typical mixtures of natural gravel and rubber of the same median sizes, i.e. no specific rubber content at which the limiting void ratios would reach a minimum. The obtained e_max values were higher than those observed in most sand-rubber and gravel-rubber mixtures, which results probably from both the higher e_max of the alternative aggregates used in this study and the different testing methodology.

Authors
Magdalena Kowalska; Bartosz Bdzionek; Katarzyna Gabrys; Iwo Zatorski

Published In

11th International Conference on Physical Modelling in Geotechnics (ICPMG2026)

Theme

Special Session 7: Geotechnical seismic isolation based on sustainable geomaterials