Effect of Pre-Soaked Expanded Perlite Aggregate on the Dimensional Stability and Mechanical Properties of ECC

This study investigates the use of expanded perlite aggregate as saturated lightweight aggregate (LWA), on the mechanical and dimensional stability properties of Engineered Cemetitious Composites (ECC). Expanded perlite aggregate was soaked in water for 24 hours before its use in ECC, and replaced 10, 20 and 30 % of the aggregate used in ECC production. The mixture proportion of a standard ECC mixture with properties extensively reported in the literature is used as a reference. The properties of specimens are compared in terms of compressive strength, flexural strength, mid-span beam deflection capacity, matrix fracture toughness, drying shrinkage, autogenous shrinkage and restrained shrinkage. Test results reveal that compressive strength and flexural strength of the specimens are adversely affected with pre-soaked LWA replacement. Mid-span beam deflection capacities are partially improved while matrix fracture toughness values are all decreased by the pre-soaked LWA replacement, which is beneficial for multiple cracking behavior of ECC. Pre-soaked LWA replacement is shown to slightly increase the drying shrinkage with respect to reference mixture. However, test results reveal that the use of pre-soaked expanded perlite aggregate in ECC production increase the age of restrained shrinkage cracking, and decrease the autogenous shrinkage capacity significantly. Therefore, together with the comparable/enhanced composite mechanical, ductility and dimensional properties with the standard ECC mixture, the use of pre-soaked LWA in ECC production is expected to improve the durability and extends the service life of structures under environmental exposures.