Recent advances in immobilization of radioactive cesium and strontium-bearing wastes in alkali activated materials - A review.

This review discusses recent advances in the use of alkali-activated materials (AAMs) to host high heat and radiation-emitting cesium (Cs) and strontium (Sr) wastes. It examines the evolution of geopolymerization, mechanical properties, mineralogy, microstructure, and leaching behavior of Cs-and/or Sr-bearing AAMs, considering their chemical interaction with Cs and Sr nuclides and exposure to temperature and gamma radiation induced by Cs and Sr. The literature indicates that Cs and Sr slightly degrade the mechanical properties of AAMs, with Sr having a more pronounced effect.

The Time-Dependent Interfacial Adhesion between Artificial Rock and Fresh Mortar Modified by Nanoclay.

The time-dependent interfacial adhesion between rock and fresh mortar is key for printing concrete linings in mountain tunnels. However, a scientific deficit exists in the time-dependent evolution of the interfacial adhesion, which can cause adhesion failure when printing tunnel lining. Nanoclay has the potential to increase the interfacial adhesion and eliminate the adhesion failure.

The Effect of Curing Conditions on the Service Life of 3D Printed Concrete Formwork.

Complex concrete elements are typically produced with lost formwork made out of timber or plastic. After usage, these timber or plastic panels are disposed of. This makes complex lost formwork a polluting and high-cost-inducing aspect of concrete construction.

Geometric Conformability of 3D Concrete Printing Mixtures from a Rheological Perspective.

The effectiveness of 3D concrete printing (3DCP) relies on understanding the rheological properties of cementitious materials and their time-dependent evolution. These materials exhibit shear-thinning viscosity, an elastic region, and both static and dynamic yield stress, which are challenging to balance in 3DCP. Layer deformation can be caused by factors such as self-weight, the weight of subsequently deposited layers, and the stress induced by the nozzle pressing.

Fresh and hardened properties of alkali-activated slag concrete: The effect of fly ash as a supplementary precursor.

The present study explores the possibility of replacing blast furnace slag (BFS) with coal fly ash (FA) to produce alkali-activated material (AAM) concrete with hybrid precursors. With an increased FA replacement ratio, the reaction kinetics, fresh and hardened properties of AAM mixtures have been investigated. The retardation effect on the reaction kinetics with an increased FA content has been observed, which not only extended the induction period along with the heat flow evolution but also reduced the cumulative heat release up to 24 h.