Abstract:
The internal curing is provided, usually, by the use of some proprietary fine aggregates which
provide sufficient water from within to promote the ongoing hydration of cement and hence result
in a relatively high performance concrete. Two concretes, one total lightweight concrete (TLWC)
and the second sand lightweight concrete (SLWC) of 28 day cube strength of approximately 40 MPa
(5800 psi) were designed. A total of six mixes were cast out of these two concretes, 4 – TLWC's and
2 – SLWC's. The variation in the mixes was due to moisture condition of the aggregates and the
use of seawater in mixing and curing of the concretes. The effect of these variations on the cube
compressive strength, water permeability, sulphate and chloride content, depth of carbonation and
shrinkage of these six concretes was studied. The presaturation of the lightweight aggregates (LWA's)
used do not seem to have improved the compressive strength, and water permeability of these
concretes. The drying shrinkage strains of the concrete using presaturated aggregates decreased
considerably. The application of seawater in making and curing these LWC's increased the compressive
strength by about 15%.