91 days from the soaking tank and tested to measure the depth of
chloride penetration. The cubes were split into two halves from the
middle and the freshly split pieces were sprayed with 0.1 N Silver
Nitrate (AgNO3) solution. The AgNO3 reacts with the free chloride
on the concrete surface and form a white precipitate of silver
chloride (AgCl). In the places where the free chlorides are absent,
AgNO3 reacts with hydroxide to form a brown precipitate of silver
oxide (AgO). Thus, the boundary of colour change indicates the
depth of chloride permeability