1. Individual pieces of large aggregate may pop out of the surface. This is often caused by chert or other absorbent aggregates that deteriorate under freeze-thaw conditions. Surface patching can be done temporarily with asphalt. For severe areas, a more permanent partial depth concrete patch may be necessary. The above is called: Pop-outs Scaling 2. Scaling is surface deterioration that causes loss of fine aggregate and mortar. More extensive scaling can result in loss of large aggregate. Often caused by using concrete which has not been air-entrained, the surface becomes susceptible to freeze-thaw damage. Scaling is also aggravated by the use of deicing chemicals. True False 3. Spalling is the loss of a piece of the concrete pavement from the surface or along the edges of cracks and joints. Cracking or freeze-thaw action may break the concrete loose, or spalling may be caused by poor quality _____________. Spalling may be limited to small pieces in isolated areas or be quite deep and extensive. Repair will depend on the cause. Small spalled areas are often patched. Spalling at joints may require full depth joint repair. Material Workmanship 4. If the steel reinforcing bar or mesh is placed too close to the concrete surface it will lead to concrete spalling. __________ of the steel creates forces that break and dislodge the concrete. Often you can see rust stains in the surface cracks before saplling occurs. Corrosion Temperature 5. Longitudinal paving joints are constructed to be narrow in width and usually well sealed. As pavements age and materials deteriorate, joints may open and further deteriorate. Cracks parallel to the initial joint may develop and accelerate into spalling or raveling of the longitudinal joint.
Settlement, instability, or pumping of the subgrade soil can cause longitudinal joints to fault. One common cause of cracks parallel to the longitudinal joints is waiting too long after the pour to saw the joint. Then, during initial cure the slab will crack roughly parallel (but not exactly) to the sawn joint.
True False 6. Transverse cracks may appear parallel to joints and can be caused by thermal stresses, poor subgrade support, or heavy loadings. They are sometimes related to slabs having joints spaced too widely. Joints spaced more than _____ apart commonly develop mid-slab transverse cracks. 15’ 30’ 45 7. Occasionally, severe deterioration may develop from ______________. So called D-cracking develops when the aggregate is able to absorb moisture. This causes the aggregate to break apart under freeze-thaw action which leads to deterioration. Usually, it starts at the bottom of the slab and moves upward. Poor quality aggregate Bad curing 8. Some pavement cracks appear to wander randomly. They may cross a slab diagonally or meander like a serpent. Meander cracks may be caused by settlement due to unstable subsoil or drainage problems, or by utility trench settlement. Frost heave and spring thaw can also cause them. They are often local in nature and may not indicate general pavement problems. True False 9. Concrete slabs may push up or be crushed at a transverse joint. This is caused by _________ of the concrete where incompressible materials (sand, etc.) have infiltrated into poorly sealed joints. As a result, there is no space to accommodate expansion. It is more common in older pavements with long joint spacing. Pressure relief joints can be installed and blowup areas must be patched or reconstructed. Expansion Extraction 10. Faulting creates a poor ride and may cause slab deterioration. Minor faulting can be corrected by _____________. Voids can be subsealed, or slabs mud jacked back to level position. Severe cases may need joint replacement. Surface grinding removing the subsoil 11. Unstable or poorly drained subgrade soils may cause pavements to settle after construction. Poorly compacted utility trenches may also settle. This may be a gentle swale or a fairly severe dip. True False 12. Replacement or repair of utilities will require cuts or utility openings. When repaired these pavement patches may show settlement, joint deterioration, or distress under continued traffic loading. Patches from previous repairs may perform like original pavement or experience joint deterioration or settlement. True False 13. The table in page 15, Rating 5 & 6 is for : New pavement or recent concrete rehabilitation. No maintenance required. First signs of corner cracks, faulting, and joint or crack spalling. Requires surface repairs, sealing or partial depth patching. Pavement failure requiring complete reconstruction. 14. According to rating system in page 16: A rating of 4 means: Severe polishing, scaling, map cracking, or spalling over 50% of the area. Joints and cracks show moderate to severe spalling. Pumping and faulting of joints (1⁄2”) with fair ride. Several slabs have multiple transverse or meander cracks with moderate spalling. Spalled area broken into several pieces. Corner cracks with missing pieces or patches. Pavement blowups. Moderate scaling in several locations. A few isolated surface spalls. Shallow reinforcement causing cracks. Several corner cracks, tight or well sealed. Open (1⁄4” wide) longitudinal or transverse joints and more frequent transverse cracks (some open 1⁄4”). Extensive slab cracking, severely spalled and patched. Joints failed. Patching in very poor condition. Severe and extensive settlements or frost heaves.