UFC 3-270-04
15 March 2001
CHAPTER 7
SUBSEALING JOINTED CONCRETE PAVEMENTS
7.1. Purpose of Subsealing. The purpose of subsealing is to stabilize the pavement slab by the
pressurized injection of a cement grout through holes drilled in the slab. The cement grout will,
without raising the slab, fill the voids under it, displace water from the voids, and reduce the
damaging pumping action caused by excessive pavement deflections. To ensure that the slab is
not raised, straightedges with gauges attached should be placed over the slab to measure any
upward movement of the slab. At the first indication of movement, the grout injecting procedure
should be stopped.
7.2. Void Detection. A thorough survey should determine the void locations beneath the
concrete pavement. Void detection measurements should be taken during the preliminary
evaluation and during the repair process. Void detection can be a complicated process as natural
wetting and drying cycles and thermal variations can cause slab curling. Several suggested
methods follow, but interpretation of field conditions by experienced personnel is always
desirable.
Several methods of void detection are in use. Perhaps the simplest is a visual inspection of the
pavement to locate areas of distress. The presence of ejected subgrade or base material,
staining of pavement surfaces adjacent to joints, vertical movement at joints or cracks, and
faulting of joints are evidence of possible voids under the slab. The most common method of
determining the presence of voids is called "proof rolling." This is the procedure of slowly driving
a heavily loaded vehicle (minimum 18,000-pound (80-kilonewton) axle load) over a transverse
joint while observing deflection of the slabs. If deflection can be visually observed, the joint
should be undersealed. Deflection can also be measured by devices equipped with sensitive dial
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