The equipment is designed to remove concrete to a prescribed depth of solid concrete and complete removal of weakened, unsound concrete. In sound concrete, the high pressure water stream enters the concrete through pores and cracks. It starts breaking up any component in the concrete that has the least resistance to the water stream. The rebar is intact and descaled. The high pressure water-jet cleans the exposed embedded rebar, removing the surrounding concrete and corrosion scale.
Aggregate is intact and washed due to the removal of concrete mortar paste.
Exposed aggregate is ideal for bonding the new overlay. It should be apparent that resistance, or the lack of resistance in concrete, is the key to the success of hydrodemolition. But, not all concrete offers the same degree of resistance. Based on thousands of hours of hydrodemolition experience, a ratio of 3.5 p.s.i. water pressure for every 1 p.s.i. compressive strength of concrete is used to calculate optimal operation pressure. If a concrete core test indicated nominal compressive strength of the concrete to be 5,000 p.s.i., a minimum water pressure of 17,500 p.s.i. is indicated.