Paths and paving – concrete cracks

Cause

Overloading of the path design/construction such as vehicles driving over footpaths or trucks using a driveway designed for car or pedestrian traffic only

Repair

  • brush or waterblast away soil, debris, weeds and loose concrete from the crack. If the crack opening is narrow but the crack is wider below the opening, chisel the edges to make the opening more accessible for repair compound. Remove all loose material. Trowel filler compound into the crack, following the manufacturer’s instructions. Proprietary filler compounds are readily available at hardware stores. Feather the edges to make them less visible then lightly broom for a slip-resistant finish. Leave to cure for the recommended time

  • repairs to cracks on paths and driveways usually remain visible. To hide these and refresh the appearance of concrete – assuming that future overloading of the concrete can be prevented – apply a proprietary modified cement coating. These typically come dry in 20kg bags and are mixed with water when used. The surface of the concrete must be clean of dirt and particles, oil and any sealers. Acid washing/grinding may be necessary (and should be done by an experienced contractor). Cracks and holes should be filled as in the first bullet point. A good bond requires a rough surface. Application is by a steel squeegee. Two coats are often applied. Finishing can be done by broom or trowel. Always follow the product manufacturer’s instructions

  • specialist companies also offer concrete resurfacing services. Products are available in a variety of colours and surface finishes

  • if overloading is likely to continue, the best solution is to replace the path/driveway with higher strength (20MPa) reinforced concrete

Cause

Poor quality concrete (low strength, no vibration)

Repair

  • as above, but consider first whether replacement of the path/driveway with higher strength (20MPa) reinforced concrete may be a better long-term option

Cause

Inadequate base preparation – concrete not thick enough

Repair

  • replacement of the path/driveway with good quality concrete may be the best long-term option. If temporary or short-term pairs are required, follow the first repair above

Cause

Unreinforced concrete

Repair

  • replacement of the path/driveway with higher strength (20MPa) reinforced concrete may be the best long-term option

Cause

Soil settlement

Repair

  • replacement of the path/driveway with higher strength (20MPa) reinforced concrete, after dealing with the settlement, may be the best long-term option. If temporary or short-term pairs are required, follow the first repair above

Cause

No expansion joints installed when the concrete was poured

Repair

  • as for the first repair

Cause

Tree roots

Repair

  • where area of damage is small, remove tree roots and damaged concrete and repair as above

  • where area of damage is larger, remove tree roots and damaged concrete and place new concrete on a compacted gravel base

  • if the problem is likely to recur, remove or replace the tree