Concrete patio – cracking

Determine the cause of the cracking as this affects the type of repair 

Causes

Shrinkage cracking

Thermal expansion/contraction and a lack of movement control joints

Frost (on fresh concrete or where water is expanding within cracks during frosts)

Building or land settlement

Earthquake - the concrete was not reinforced

Common

Listed under: Exterior, concrete and cement, earthquakes, patios

Cause

Shrinkage cracking

Repair

  • Drying shrinkage - too much water was used when the concrete was mixed 
  • Plastic shrinkage - crazed cracking that occurs if the surface is allowed to dry out before the concrete has gained sufficient strength
  • If the cracking is not severe (if it is hairline or crazed cracking) it may be left or be resurfaced using a proprietary modified polymer concrete coating. 
  • Slightly larger cracking may be filled with a proprietary epoxy grout or modified polymer concrete coating: waterblast to clean the concrete surface before filling cracks, then grind the surface smooth after the fill material has cured if necessary 
  • If the cracking appears severe, monitor the width of a crack for a month; if it increases in size, obtain specialist advice from a chartered professional engineer

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Cause

Thermal expansion/contraction and a lack of movement control joints

Repair

  • If the cracking is not severe (if it is hairline or crazed cracking) it may be left or be resurfaced using a proprietary modified polymer concrete coating. 
  • Slightly larger cracking may be filled with a proprietary epoxy grout or modified polymer concrete coating: waterblast to clean the concrete surface before filling cracks, then grind the surface smooth after the fill material has cured if necessary 
  • If the cracking appears severe, monitor the width of a crack for a month; if it increases in size, obtain specialist advice from a chartered professional engineer

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Cause

Frost (on fresh concrete or where water is expanding within cracks during frosts)

Repair

  • If the cracking is not severe (if it is hairline or crazed cracking) it may be left or be resurfaced using a proprietary modified polymer concrete coating. 
  • Slightly larger cracking may be filled with a proprietary epoxy grout or modified polymer concrete coating: waterblast to clean the concrete surface before filling cracks, then grind the surface smooth after the fill material has cured if necessary 
  • If the cracking appears severe, monitor the width of a crack for a month; if it increases in size, obtain specialist advice from a chartered professional engineer

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Cause

Building or land settlement

Repair

  • If the cracking is not severe (if it is hairline or crazed cracking) it may be left or be resurfaced using a proprietary modified polymer concrete coating. 
  • Slightly larger cracking may be filled with a proprietary epoxy grout or modified polymer concrete coating: waterblast to clean the concrete surface before filling cracks, then grind the surface smooth after the fill material has cured if necessary 
  • If the cracking appears severe, monitor the width of a crack for a month; if it increases in size, obtain specialist advice from a chartered professional engineer

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Cause

Earthquake - the concrete was not reinforced

Repair

  • If the cracking is not severe (if it is hairline or crazed cracking) it may be left or be resurfaced using a proprietary modified polymer concrete coating. 
  • Slightly larger cracking may be filled with a proprietary epoxy grout or modified polymer concrete coating: waterblast to clean the concrete surface before filling cracks, then grind the surface smooth after the fill material has cured if necessary 
  • If the cracking appears severe, monitor the width of a crack for a month; if it increases in size, obtain specialist advice from a chartered professional engineer

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