Geotechnical Properties of Blends of Recycled Clay Masonry and Recycled Concrete Aggregates in Unbound Pavement Construction

Abstract

This paper presents the engineering characteristics of blends of recycled clay masonry (RCM) with recycled concrete aggregate (RCA) from two material producers from South Australia. The proportion by dry mass of RCM was 20% of the total mass. Results are reported of standard engineering classification tests and static and repeated loading triaxial tests (RLTT). Specimens were tested between 60 and 100% of optimum moisture content (OMC) and at a constant dry density ratio. Matric suctions were measured by the filter paper method to study the influence of suction on strength and to establish soil water characteristic curves (SWCC). Triaxial testing indicated that cohesion varied between 9 and 89 kPa and was dependent on molding moisture content, matric suction, and the material source. Resilient modulus and permanent strain were also influenced by suction. Permanent deformation was able to be modeled successfully using a relationship developed between number of load repetitions and initial matric suction. Based on the laboratory testing program, the recycled clay masonry blends appeared to be suitable for application as subbase.