Note that air entrainment refers only to the microscopic air bubbles created by the admixture, and not the visible voids often seen in cast-in-place concrete after the forms are removed. Large-sized or numerous voids are a result of poor consolidation during placement, and result in reduced strength and durability of the concrete.
Ready mixed concrete is supplied only after exhaustive laboratory & plant trials. To ensure consistent quality, incoming raw materials are regularly tested. Sampling & testing of ready mixed concrete is done everyday as codal stipulations. At RMC Readymix (India), buyers are invited to visit our laboratories to witness the process.
These defects are, generally, a result of improper finishing of the concrete. The prime factor affecting concrete strength is water / cement ratio. If excess water is added to the surface of the concrete during placement & finishing, the water / cement ratio on the surface may be drastically increased. This condition greatly reduces the strength of the concrete on the surface. Unfortunately this is where the wear takes place.