Repeated Load Triaxial Testing of Recycled Excavation Materials Blended with Recycled Phyllite Materials.

Solomon Adomako,Rein Terje Thorstensen,Diego Maria Barbieri,Christian John Engelsen

doi:10.3390/ma15020621

Solomon Adomako, Rein Terje Thorstensen + Show 2 more

Open Access

https://doi.org/10.3390/ma15020621

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Abstract

Recycled Excavation Materials (REM) are becoming viable alternative construction resources due to their economic benefits. However, REM may be composed of weak rocks, e.g., phyllites, limiting the use in a base layer. The present paper attempts to further the knowledge of the mechanical performance of REM by performing Repeated Load Triaxial Tests (RLTT). REM are mixed with Recycled Phyllite Materials (RPM) in systematic blends of 0%, 25%, 50%, and 100%. The batches’ resilient modulus (MR) and permanent deformation (PD) characteristics were assessed to establish the maximum RPM allowed into REM while maintaining the required performance. Hicks and Monismith’s and Uzan’s models were used to characterize the stiffness behavior. A wide variation in the stiffness between the two materials was observed. Batches comprised of 0% RPM–100% REM and 25% RPM–75% REM showed high stiffness performance. The Coulomb model assessed the PD behavior, and the results showed a similar response for all batches. Unlike the stiffness, blended mixtures did not show sensitivity to increased RPM content in the PD. This study may help end-users to understand the performance of REM given the documented threshold on the allowable quantity of RPM in REM.

Highlights

Construction and demolition waste (CDW) is by far the heaviest and voluminous waste stream, accounting for 35% of total waste produced globally [1]
recycled masonry aggregates (RMA) is sourced from crushed rubble, recycled concrete aggregates (RCA) is obtained from demolished concrete structures, whereas mixed recycled aggregates (MRA) consists of mixtures of RMA, ceramic tile, bricks and RCA
The results showed that up to 30% recycled glass is regarded as optimum to be added to crushed rock (CR), considering that stiffness and permanent deformation (PD) behavior showed sufficient response just like natural aggregates

Summary

Introduction

Construction and demolition waste (CDW) is by far the heaviest and voluminous waste stream, accounting for 35% of total waste produced globally [1]. Given the reported studies and previous research on RA, the almost non-existent research and knowledge of the stiffness and deformation behavior of REM and RPM mixes under repeated loads limit the use of REM composed of occasional amount of weak rocks. This makes REM complete waste materials suffering the fate of landfill, which is not suitable from an environmental point of view. The findings may promote the use of REM as road construction materials

Materials and Methods

Findings

50 RPM–50 REM