Masonry Pavement
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Masonry pavement is either constructed of brick or concrete pavers.
A masonry paver system is constructed on a foundation of sand, a base course, and properly compacted soil. Fine sand is deposited in between the individual paving units using a vibratory plate compactor tamper to further stabilize the block layer.
(a) The surface is composed of a layer of concrete pavers.
(b) Pavers are assembled on compacted sand.
(c) Base course provides additional support, allows for drainage, and provides resistance to freezing.
(d) Subgrade is compacted soil and provides the foundation of the pavement structure. It can become harder and more stable over time.
Common Failures of Masonry Pavement
Masonry pavement experiences the effects of climate along with wear and tear and can be considered a maintenance-incentive surface. Construction defects related to masonry pavers can be due to deficient engineering design, methods, or materials.
Failures of masonry pavers present in the form of surface distortion, settlement, heaving, and separation.
SURFACE SLOPE
Due to the surface characteristics, masonry pavement should be installed at slopes between 2% (1/4-inch per foot) and 4% (1/2-inch per foot). Masonry pavers placed at less than 2% do not adequately shed drainage.
Bird baths (shallow standing water on pavement) are caused by inadequate pavement slope, preventing the surface from properly draining. Low points holding water of only a depth more than the thickness of a coin are hazardous and can lead to slippery or icy conditions. It is often difficult for pedestrians to notice or gauge how deep a shallow depth of standing water is and take the proper precautions when traveling on such a surface.
DRAINAGE
Water is the greatest enemy of sand and soil which supports the masonry pavement.
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Typically, water enters the subgrade through separations between individual pavers and edges from adjacent areas. Infiltration of water into supporting materials weakens the bearing capacity of the soil and can result in failure.
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More information about maintaining proper drainage around pavement >>
SURFACE DISTORTIONS
Surface distortions are caused by loading and/or a weakened subgrade. Masonry pavement can be weakened by wetting of the sand and soil below the pavers.
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Deposits of sediment on the surface are indicative of standing water from rain.
SETTLEMENT, HEAVE, AND HORIZONTAL DISPLACEMENT
A typical cause of the settlement of masonry pavers is inadequate compaction of the subgrade material, which may be related to water infiltrating into the subgrade. Upward vertical movement can be caused by expansion of the soil below the masonry units or frost heave (freezing of soil). Horizontal displacement of the masonry units is caused by lateral forces on the weakened pavement.
SEEPAGE
Seepage is caused by drainage water infiltrating in or flowing out of the soil and sand below the paver layer.
DESIGN STANDARDS FOR MASONRY PAVEMENT
Engineers design masonry pavement per applicable criteria of a specific Jurisdiction or Agency. These criteria dictate the thickness of the sand layer, and the depth of the supporting subgrade depends on weight loading and the amount of traffic.
It is important to note that masonry pavement requires regular maintenance and repair to achieve its full design life.
