Concrete Transition Zone and Its Porosity

The concrete transition zone is the thin region where aggregate meets cement paste. It has more pores than the surrounding material, so it is usually weaker at first. The bond around the aggregate comes mainly from Van der Waals forces, which are weak attraction forces between particles.

When con...

The transition zone, found where the aggregate meets the cement paste, is more porous and, as a result, weaker than hydrated paste beyond the transition zone.

First, when concrete is freshly compacted, films of water surround the larger aggregate particles, which can result in a greater water-cement ratio near these aggregates compared to...