BEHAVIOR OF RECYCLED CONCRETE AGGREGATE IMPROVED WITH LIME ADDITION DURING CYCLIC LOADING

Abstract

In this paper, study on the use of reclaimed waste in Recycled Concrete Aggregate (RCA) was
conducted. Reclaimed concrete problem has increased over the past decade, due to the replacement of the old
concrete parts, such as rail substructures or pavement curb. The main idea of this article was the introduction of
recycled materials to pavement engineering, which in Poland were usually deposited on waste landfills.
Geotechnical study was undertaken to obtain physical and mechanical properties of RCA. For better
understanding of its exceptional behavior under repeated loading, cyclic triaxial test was conducted in various
stages of loading. For the purpose of bearing capacity analysis, uniaxial tests were made. Moreover, RCA
improvement of mechanical properties was proposed. Chemical stabilization with lime and gypsum was
undertaken in order to ameliorate mechanical characteristics. While the mechanical stabilization is a cause of
aggregates crushing, created fine fraction could be a stabilizing medium. Stabilization process in this study
demonstrates existence of free pozzolanic compound in crushed concrete. Determination of resilient modulus Mr
from repeated loading test for non-stabilized and stabilized material was also presented for non-stabilized and
stabilized RCA Mr value was 543.2MPa and 816.5MPa respectively. In this article, plastic strains occurrence
was also analyzed. As a brittle material, RCA can response to cyclic loading by crushing. Repeated excitations
can cause another mechanism of plastic strains development, not present in natural aggregates, where main
causes of plastic strains are frictional forces occurring during contact between particles.