Robust layer interface in cement additive manufacturing via silicate penetration and precipitation

Abstract

Weak layer interface is a non-negligible issue in the domain of cement additive manufacturing, which results in lacking integrity, mechanical inferiority and deteriorated durability. In order to overcome these disadvantages, a silicate-based interface strengthening agent (ISA) is herein designed to penetrate into layer interface and generate a dense precipitation phase (hydrated calcium silicate gel) from the reaction with portlandite, a weak phase with lower mechanical properties. Through this enhancing strategy, both horizontal and vertical layer interface exhibit remarkable bonding strength higher than that of matrix material, turning the intrinsic weak interface to a “robust interface”. The strengthening mechanism is attributed to the modification of interfacial hydration products and the densification of multi-scaled pore structure at interface region, which is demonstrated via synthetical characterizations along with molecular dynamics simulations. This interface strengthening method based on silicate penetration and precipitation provides a convenient and effective approach to preparing robust layer interface stronger than its cement matrix.