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What’s Cracking the Concrete?

Concrete cracks can be caused by many different issues and are an inevitable result of the typical wear and tear of construction. Whether the cracks are a problem for your structure or just a cosmetic flaw, there are precautions which can be taken to avoid them.

Concrete cracks can be caused by many different issues and are an inevitable result of the typical wear and tear of construction. Whether the cracks are a problem for your structure or just a cosmetic flaw, there are precautions which can be taken to avoid them.

To ensure that you are preventing the concrete cracks, it is important to understand where they come from. Concrete in its non-solid state consists of water and cement - when the water evaporates, the concrete shrinks, causing it to solidify. Cracks can appear after too much shrinkage so to avoid this, stick to the 0.5 rule – this means that with every kilo of cement that you use, add half a kilo of water. Concrete tends to adapt and change depending on its surroundings. Because of this, it will expand in hot weather, pushing into surrounding objects. If those objects are unable to doge the pressure of the rising concrete, then cracks will appear in the surface.

Usually, ground movement around the concrete can have a damaging effect, for example; pathways, roads and driveways. As the concrete recovers from freezing temperatures or suffers a shift from a tree root, it will crack and break in a process called ‘heaving’. In addition to this, movement in the soil due to rotting tree roots or excessive water flow can cause damage to the foundations of the concrete which is known as ‘settling’. While seemingly evident, the overload of a slab is an issue that is often overlooked, and it is crucial to be aware of the consequences from applying too much pressure to the concrete otherwise, it will weaken and break over time.

Crazing and crusting can be seen when concrete has not had enough time to dry. Crazing applies to damage caused by a rapid loss of moisture in the mixture and crusting is the term for artificial imprints left on improperly dried concrete. Thicker slabs are more prone to surface crusting due to the dramatic difference in moisture levels and temperature between the bottom and the top of the slab. Another cause is the greater underlying soft belly which results in a wavier surface as finishers attempt to trowel the concrete .

Structural Defects Insurance

Along with avoiding the potential long-term damage, there are also precautionary measures to be taken when laying and setting the concrete for example, ensuring a regular ground temperature.  When laying concrete on thawed platforms, you are risking uneven settling as the layer of fresh mixture which is closest to the frozen ground is likely to set slower than the outer layer, making the bottom softer than the top. In addition to this, this rule applies to the tools and equipment needed for tools and machinery used in the laying of the mix. An extra step which could be taken to avoid any damage would be to take advantage of suitable time periods – working in the day does not only provide an abundance of light, but also the heat and warm weather can aid your concrete to set properly. It is strongly advised that, in cold weather, all work should be postponed until the air temperature is above 2* Celsius.

To avoid weather induced damage, it is important to consider the weather and local topography, planning ahead and acknowledging the forecasting services, either by stopping work or taking adequate precautions. As further guidance, there are multiple services available to ensure that the building process can under go in the appropriate environment, for example:

  • Pre-recorded weather forecasts on the WEATHERCALL telephone services
  • Weather forecasts specific to contractors’ needs
  • An assessment of time when suitable working conditions will prevail in a given area.

All of these services are provided by the Meteorological Office.

Concrete cracks are not usually a concerning issue unless the flaws are in close proximity to any supportive pillars, roads or sidewalks - A common fault is when water gets into a crack in freezing climates causing the damage to expand however, if you notice a crack in the concrete, there is little cause to worry as this problem can be fixed with a fill-in solution or replaced with a new slab.

 

Specialists in Construction Insurance

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