A review of preplaced-aggregate concrete using recycled aggregate and railway wasted ballast

Preplaced-aggregate concrete is used when normal concrete cannot be cast. In this method, coarse aggregate is put in a formwork, then non-shrink grout mortar is poured into it so the aggregate surrounds are filled with the material. An advantage of preplaced-aggregate concrete is that construction waste can be used as coarse aggregate. However, the durability of the concrete structure when using preplaced-aggregate has not been clarified. It is considered that the properties are different between normal concrete and preplaced-aggregate concrete because of the different method of casting. In this research paper, preplaced-aggregate concrete and ordinary concrete were cast using various aggregates and their properties were analyzed by comparison. For aggregate, it was used recycled aggregate, railway wasted ballast, and normal coarse aggregate. Compressive strength test and the air permeability test were conducted. In addition, the porosity was calculated by the Archimedes test. Preplaced-aggregate concrete did not show difference in strength even when the type of aggregate was changed, and there was no significant difference in pore ratio, concluding that it does not depend on aggregate.