Crack Control

Expansion Cuts (cracking control)

There are 2 things that can be guaranteed with concrete the first is that it will crack and the second is that it is theft proof.
As far as cracking is concerned the only thing to help overcoming this process is what is known as crack control. First and foremost is reinforcement, concrete by nature is a very strong compressed product but lacks in strength without steel reinforcement to hold it all together.

Steel reinforcement should be placed throughout the entire job leaving only 50mm around the perimeter of job. Another tip is using extra 12mm reinforcement bars on corners, as concrete is known to and will always crack in the weakest place first and corners are cracking points whether it is a corner of a house or a corner of a pit or drain that has been incorporated in the concrete for drainage. By placing 2 x 1.2m long bars on the angle in front of the corner and 50mm apart plays a bit part in strengthening a weak point thus reducing the chance of cracking.

Another preventative measure is adequate expansion joints all round the slabs perimeter wherever the concrete is up against brickwork or other concrete, tiles, pavers, etc. expansion joint must be placed in between the 2 because concrete does expand and contract, that is a certainly.  Let me give you an example, if you were to have your driveway concreted and the person you went ahead with to do the job failed to place expansion joints on the edge of your driveway where it was up against the house and the other side you also had brick work or even the neighbour’s driveway, whatever the case may be this is just an example, when the concrete moves due to temperature change it will give somewhere.

If you’re lucky it will be your driveway that cracks but equally likely so will the brickwork on your house in the form of a great big crack running up your wall.  Now I don’t want to alarm you, I merely want to you to be armed with the best knowledge possible when it comes time to spend your hard earned money.  Unfortunately there are trades out there that are either inexperienced or plainly just don’t care. Sub grade preparation is another key to crack control a solid foundation is key principle to build a house on so this mentality should be used in construction of your driveway, after all you will be driving over it.

Now the weather plays a big role in this industry, it is the uncontrollable factor that changes an experienced contractor’s train of thought on how they go about the day’s tasks.  Concrete laid in the proper manner keeping the weather temperature and forecasts in mind contributes to cracking control.  For example, if it’s a cold day the things I would consider are the path the sun takes through the day, as shade plays a big part in

curing times therefore I would start in the shade where possible whilst placing the concrete at a considerable slump. I would also consider the access around the job and the style of concrete being created, different techniques have a different process and therefore a different train of thought, I would consider using accelerant additives in the concrete and the percentage I would add would depend on the above circumstances.  You could also consider boosting the strength of concrete meaning more cement would be added when the concrete is batched thus increasing the curing time and the actual strength of the concrete itself.

Here are a list of sample questions you may want to consider

• How thick will the concrete be and what strength will be used?
• Do you or will you take care of all council requirements and inspections?
• How many coats of sealer do you apply?
• When will you and where will you put necessary expansion cuts?
• Will you put a protective film around the house for protection?
• Have you done many jobs in this area?
• How busy are you?
• Do you or can you give any kinds of guarantees?
• Who and how long did you work for to obtain your skills before starting your own business venture?
• How long have you been in your own business?
• Do you take care of all aspects of the job or do you outsource some elements like excavation and plumbing?
• Have you got relevant insurances i.e. public liability and workers cover
• Do you use employees or subcontractors for your team?

This is just a small list of questions I would be asking and they could be used in other trades also, for me you would have to tick all boxes to do the job.