Investigating mechanism for mortar-porous aggregate interfacial bond improvement based on coupled XCT-DVC analysis

Abstract

Interfacial property enhancement through increased mortar flowability could be a feasible method to improve overall behavior of lightweight aggregate concrete (LWAC). However, the underlying mechanism improved LWAC mechanical properties through altering mortar-aggregate interaction was yet fully understood. To fill this gap, the underlying mechanism was investigated in the present study through quantifying ITZ bond behavior. The interfacial bond performance was characterized by an XCT-DVC-based analysis method on samples cast with varying superplasticizer dosages. The XCT test results showed that the mortar with a high flowability had a higher penetration depth inside the porous aggregate. Analysis of the DVC results showed that a better mortar penetration could improve the synergistic deformation capacity between matrix and aggregates, which in turn enhanced the overall mechanical strength. But not all penetrated areas could fully contribute to the bond strength. The penetration area of mortar can be further classified into well-bonded and poorly-bonded zones according to the matrix-aggregate interaction condition and the contribution of ITZ in load transfer.