Autogenous shrinkage effects on high strength concrete with mechanically treated and internally cured aggregates

Abstract

The growing urgency to preserve natural resources has spurred the adoption of recycled concrete aggregates (RCA) in the production of conventional concrete. However, a significant drawback of recycled aggregate concrete (RAC) lies in the presence of hardened paste surrounding the aggregates resulting in an overall decrease in the material properties. To address this concern, various techniques for treating RCA have been employed to remove the adhered mortar partially or fully from the RCA's surface, aiming to enhance mechanical and durability properties. Additionally, internal curing of RCA has been investigated to enhance mechanical and durability properties. This study employs ASTM C1581 and EN 12390-16 standards to evaluate shrinkage, specifically autogenous and drying shrinkage, and investigates the correlation between these tests. Furthermore, this study explores the impact of RCA on mechanical and durability experimental tests such as compressive strength, porosity, sorptivity etc. The findings demonstrate that internal curing of treated RCA effectively reduces drying and autogenous shrinkage, reducing the risk of cracks. This positive outcome is mainly attributed to the internal hydration of cement from the saturated surface dry condition of the aggregates, also enhancing overall properties of RAC, Finally, an innovative testing apparatus for large-scale autogenous shrinkage testing is proposed based on ASTM C1698. This new approach offers a promising pathway for accessing concrete’s autogenous shrinkage and advancing our comprehension of RAC’s performance.