Common Types of Pavement Cracks in Houston

Pavement may crack even when installation and environmental conditions are ideal. However, incidental cracking tends to be minor and will not threaten the pavement’s stability, although common types of cracking do merit a deeper inspection by a reputable paving contractor. Those cracks include:

• Shrinkage cracks – Shrinkage cracking (sometimes termed plastic cracking) affects newly poured concrete, in most instances. Shrinkage cracks emerge soon after curing and only affect the pavement’s surface. As such, they will not threaten the pavement’s structural integrity, but they may affect the concrete’s appearance. The best way to address shrinkage cracking is to prevent them in the first place. Proper curing techniques, adequate curing time and using quality concrete mixes (perhaps with anti-shrinkage additives mixed in) can protect against shrinkage cracks.
  
  
• Settlement cracking – Settlement cracks also appear soon after the concrete is poured and cured. They are the result of “voids” or gaps opening under the concrete before it has a chance to fully cure. In most cases, these voids are the result of poor soil compaction, which causes the base to shift and open gaps under the concrete that is still somewhat pliable.
  
  

  Another common cause of settlement cracks in Houston is voids opening around steel reinforcement or rebar. As water evaporates out of the fresh concrete, the resulting downward movement may stress the pavement and cause cracks to form over the reinforced spots. Again, proper curing techniques and ample curing time are essential to prevent this type of cracking.

• Expansion cracks – Expansion cracks tend to emerge in straight, sharp lines and are usually caused by excessive thermal loads or loss of moisture. As such, they are also termed thermal cracks, and as elevated temperatures are the norm for Houston, expansion cracks are common. Expansion cracks can be repaired with a flexible crack sealer, but prevention is always preferred. Quality concrete mixes and proper expansion joint placement are essential for protecting against expansion cracking.
  
  
• Heaving cracks – When concrete heaves, it shifts noticeably from its original spot. This will result in severe cracks or fractures that necessitate full slab replacement. Heaving is normally the result of freezing temperatures causing the pavement’s base to expand and exert upward pressure on the concrete. Freezing temperatures are not a normal problem in Houston, but wet conditions are, and these can also cause the concrete’s base to shift and subside, resulting in heaving cracking.
  
  
• Fatigue cracking – Fatigue cracks are also known as alligator cracking for its scaly appearance and is a common type of asphalt cracking in Houston. This type of pavement cracking is characterized by an area of crisscrossing small cracks that may be due to many factors. The factors include poor base compaction, water intrusion and excessive loading. If the pavement’s base is still in good condition, fatigue cracking may be addressed with an asphalt overlay. However, if the base is compromised, the failed asphalt will need to be removed and the base issues addressed before new asphalt can be installed.
  
  
• Edge cracking – Edge cracks emerge near the asphalt’s perimeter and are most common on Houston roads and parking lots. Edge cracks are typically the result of poor edge reinforcement or overgrown vegetation along the asphalt’s edges. These are correctable issues and edge cracks can often be repaired by filling in the cracks with an asphalt emulsion. The underlying factors will need to be fixed to prevent edge cracks from re-emerging. This may include reinforcing the asphalt’s perimeter, removing tree and shrub roots and improving drainage through the property.
  
  
• Slippage cracks – Slippage cracks are crescent-shaped and tend to form around areas where the asphalt has warped. Slippage cracking is usually caused by a poor-quality asphalt mix or is the result of contaminants (water, dirt) entering the mix during installation. This will result in poor adhesion between asphalt layers, which will cause those layers to separate and crack once traffic-related loading forces are applied. The standard way to address slippage cracks is to remove the asphalt’s surface layers until a layer with good adhesion is identified. The pavement is then patched above this stable layer.
  
  
• Reflective cracks – Reflective cracking is more common in asphalt and indicates that deeper pavement layers are under stress. If you have recently repaired your asphalt, only for cracks to quickly reappear, you are likely dealing with reflective cracks. They are so named because any problems with the base or subsurface layers reflect on the pavement’s surface. The only way to fix reflective cracks is to remove the asphalt’s surface and repair any base issues before patching or overlaying.
  
  
• Transverse and longitudinal cracks – Transverse cracks run perpendicular to the pavement’s surface, while longitudinal cracks run parallel. They can affect both concrete and asphalt. Shrinkage is a primary cause of transverse and longitudinal cracking, along with poor joint placement. Thermal and traffic loads can accelerate both types of cracks. Longitudinal and transverse cracks may be addressed with crack sealers or by installing an overlay.