How do I know what type of concrete to use?
Concrete is one of the oldest building materials known to man. It is made of aggregates (stone and sand), cement (binder or glue) and water. When mixed in the correct proportions, it can be used for many different purposes.
To know the use or function of the concrete is important, the mix-design of concrete that is used for footings would be different to that of a house slab, a driveway or even pre-cast panels.
How much concrete do I need for my job?
Every job is different, however if you follow some basic rules it is easy to get an idea of how much concrete you will need.
Concrete is purchased by the cubic meter (m3) and is placed by the square meter (m2). For normal household concrete the depth or thickness of the concrete is 10cm or 100mm. That is for every m3 of concrete 10m2 is placed.
If you measure the area of concrete required in m2, divide that number by 10, that is how much concrete is required.
How do I know I have a good quality tradesman?
It is easy to know you have a good quality tradesman, first of all the quote will be professional and itemised. Normally the business will come recommended, have good reputation and a long trading history.
The business should offer referees and inspections of similar jobs to your own. If you want a good job, with less risk, expect to pay a little more.
Always remember, you get what you pay for, if your concrete crew has one less man, there will be less finishing work done and more chance that your job could go wrong.
Outwest only recommends tradesman that are experienced, professional and knowledgeable about concrete.
How do find a good tradesman?
Finding a concreter is an important aspect of undertaking concreting projects. There are many factors to consider, experience, reputation and your confidence in their abilities.When making the decision to hire a professional concreter, it is important to consider each of the following points:
- DON’T PAY FOR THE JOB UP FRONT, it is normal to pay a deposit at commencement, with the balance being paid on completion. If you concreter asks you to pay in full up front or cheaper for cash GET RID OF THEM. If you pay in full they may never turn up to do the job. If you pay cash/no receipt and there is a problem with the job in the future, you will have no documentation/proof.
- Always sign a quote with your concreter. Make sure that the quote includes all details of the work to be completed. This ensures that the costs and terms of the project are agreed upon before the commencement of the project and thus cannot be changed without the agreement of both parties.
- Ensure that your chosen concreter has the correct insurance and is properly licensed. Licenses and insurance will protect you should anything go wrong with your concreting job. Ask to see their insurance certificates and ensure that they remain current for the duration of the project.
- Reputation is an important thing to consider when hiring a concreter. Ask for references and try to speak to referees yourself where possible. Your concreter should also have a good working relationship with your local council.
- “Shop around”. Take the time to obtain more than one quote. Speak to your concreter so you are able to familiarise yourself with them, and also find out if they are capable of giving you the results that you want with your home improvements. It’s important that your concreter is able to follow your design brief and that you are confident in their abilities. The Cheapest quote is NOT usually the best quote, as everything in life, you get what you pay for!
What steps are involved in concreting?
There are essentially 4 steps in concreting:
Firstly you need to plan what you are doing and decide on the type of your concrete you require (use this website Applications/Finishes). Excavation works then are normally carried out and boxing constructed where the concrete is to be placed.
The concrete is then delivered and generally arrives on site in large mixing trucks (called agitators), these can deliver 7m3 or 70m2 of concrete area.
These trucks are then discharged through a pump (wheel barrows are slow and costly due to being labour intensive) and placed in the form work, bull floated and screeded. When the concrete is almost hard it is finished.
Concrete can go hard slowly (cold weather) or quickly (hot weather). The mix-design can be changed to suit these conditions; however the process of placing and finishing concrete needs to be adjusted for all the differing weather conditions.
Wind and Sun will also effect the finish of concrete and steps need to be taken to protect it when placing and finishing the concrete. The concrete should also be cured after it is finished.
Concrete generally is poured early in the morning and finished early afternoon, if the concrete is to be exposed it is then washed either late at night or early the next morning. Concrete is stamped at the end of the finishing stage. Concrete cuts should be done the next day, while decorative cuts can be done at any time after the concreting has been completed.
When the concrete is suitably cured and dry it is then sealed to protect it and make it easier to clean. There are a variety of sealers available, from surface sealers which have a "wet look" appearance to "natural look" penetrating sealers.
For more information on sealers for concrete, please visit: http://www.concretecoloursystems.com.au/
Is concreting a DIY project?
Concreting is generally a specialised field. Although looking easy, trowelling and finishing techniques are needed, it is hard back breaking work and a little more complex than it looks. A qualified concreter is a must on any project.
What happens if I add too much water in on site:
Whilst adding water in on site will make it easier to place the concrete, the bad side of this includes pretty much all of the following.
- Lower compressive strenghts
- Segregation of the concrete. (segregation is when the course , fines and cement paste become seperated)
- Cracking, with too much water, there will be lower tensile strengths, and a tendency towards shrinkage cracking.
- Dusting- bleeding of excess water brings too many fines to the surface which will end up in a dry and dusty surface when concrete is dryed/hard.
- Costley losses- costly repairs, or in extreme situations, ripping out the job and re pouring at the contractors cost.
For more information on all this and anything else to do with concrete have a look at the