Investigation of one-dimensional compression and stress-strain-strength relations of synthetic lightweight aggregates composed of coal fly ash and thermo plastics

This study examines the consolidation and triaxial characteristics of innovative manufactured synthetic lightweight aggregates (SLAs) consisting of high carbon flyash (80% by weight) co-extruded under a thermal process with various plastics (20% by weight). Plastics used include high-density polyethylene (HDPE), low-density polyethylene (LDPE), polystyrene (PS), and a mixed plastics (MP) blend that includes five different types of polymer resins. Natural lightweight aggregate, that is expanded clay/shale, and a natural sand obtained from Cape Cod, MA were also investigated for comparison. An equivalent grain size distribution was produced for all the aggregates. A new technique for testing granular soils, termed volume control, was introduced. This new technique controls and accommodates the relative density and its effects on the behavior of granular soils in consolidation and triaxial tests.; The obtained results showed the SLAs to have specific gravity of 1.6. The results of consolidation tests showed that, unlike sand, SLAs exhibited ductile (creep) behavior, which continues for an appreciable period of time. The results of triaxial tests confirmed that the shear strength and internal friction angle of the SLAs are comparable to that of normal sand and natural lightweight aggregates. Accordingly, SLAs aggregates could be used as a load (or non load)-bearing material such as embankment fill or fill behind retaining walls, fill around basement walls and highway underdrain systems.