Mechanical, hydraulic, and particle breakage properties of recycled concrete aggregates blended with autoclaved aerated concrete (AAC) grains for unbound road base and subbase materials in Vietnam

With the increased use of autoclaved aerated concrete (AAC) in the construction sector, the generation of AAC scrap is increasing in plant manufacturing and construction demolition works, but its reuse and recycling is limited compared to other typical construction wastes such as concrete and asphalt. To examine the use of AAC scrap for roadbed materials, this study investigated mechanical properties such as compaction curves and bearing capacity [i.e., California bearing ratio (CBR)] as well as the particle breakage, and hydraulic properties of well– and poorly–graded recycled concrete aggregates (RCA) blended with AAC grains made from AAC grains in different proportions (f) on a mass basis.The results showed that the compaction curves were mainly affected by particle size distribution and f. The f ≤ 30% is recommended for use as unbound roadbed materials based on the CBR results. The breakage of RCA itself was reduced due to the cushioning effect with increasing of f and the easily breakable property of AAC grains controlled the mechanical and hydraulic properties. The sudden increase of overall particle breakage for the tested samples with f > 30% and in the unique hydraulic properties for the tested samples mixed with different sizes of AAC grains.