Rigid Pavement Distress
An introduction to common forms of distress in rigid pavements.
Alkali-aggregate reaction is the expansive reaction that takes place in PCC between alkali (contained in the cement paste) and elements within an aggregate. The most common is an alkali-silica reaction. This reaction, which occurs to some extent in most PCC, can result in map or pattern cracking (see Figure 1), surface popouts and spalling if … Read more
Description Pattern or map cracking (crazing) on the PCC slab surface caused by reactive aggregates. Reactive aggregates are those that either expand or develop expansive by products when introduced to certain chemical compounds. Problem Roughness, an indication of poor aggregate – will eventually lead to PCC slab disintegration. Possible Causes This type of distress is … Read more
Description Small pieces of PCC that break loose from the surface leaving small divots or pock marks. Popouts range from 25 – 100 mm (1 – 4 inches) in diameter and from 25 – 50 mm (1 – 2 inches) deep. Problem Roughness, usually an indicator of poor material Possible Causes Popouts usually occur as … Read more
Description A localized upward slab movement and shattering at a joint or crack. Usually occurs in spring or summer and is the result of insufficient room for slab expansion during hot weather. Problem Roughness, moisture infiltration, in extreme cases (as in the second photo) can pose a safety hazard Possible Causes During cold periods (e.g., … Read more