Frequently Asked Questions at Keohane Readmix, Cork

Readymix FAQ

How can I contact Keohane Readymix ?

Click here for details on how to contact us by telephone, post, fax or email.

What areas does Keohane Readymix deliver to ?

Click here to visit our plant locator to find out whether we can supply ready mixed concrete in your area.

What mix do I need ?

The type of concrete mix depends on the application you need it for. Different mix specifications are used for different purposes. Higher-grade or higher-strength mixes are used for flooring and external paving whereas lower grade mixes are used for foundations.

Please note that adding water to a mix will:

  • Reduce the compressive strength of the concrete.
  • Increase the potential for shrinkage and cracking.
  • Increase the possibility of segregation.
  • Increase the potential for future problems with the surface finish

Therefore, if you think that the mix is too stiff, ask before adding water.

If you feel that you require a mix which is easier to handle, or helps you produce a good all-round finish or cuts down on the labour required to lay the concrete, please let us know and we can suggest the correct mix from our existing mix selection or may even be able to design one for you. If you are still unsure of your requirements, please contact us and we will be happy to advise you.

How do I calculate how much concrete I need?

Concrete quantities are measured in cubic metres. To work out how much concrete you will need, use our concrete calculator on the left of the page.

How much does a cubic metre of concrete weigh?

One cubic metre of concrete weighs around 2.4 tonnes.

How much notice do I need to give when ordering concrete ?

Ideally a minimum of 24 hours notice is required for concrete orders, but the more notice you give, the greater the likelihood that we can agree the time of delivery with you. All orders will be confirmed with you by telephone as early as possible.

How can I pay for the material ?

Payment can be made by cheque or cash on the day of delivery, by Visa, Mastercard or Switch at the time of ordering, or for trade customers through a credit account, subject to status. Credit and / or bank references may be required.

Will the truckmixer be able to get to the job?

It is important that the truckmixer has safe and reasonable access to the job, as we cannot be held responsible for damage caused to footpaths, driveways, kerbs, lawns, drains, manholes, etc. Be aware that truckmixers when loaded could weigh in excess of 15 tonnes. Please remember that it is the responsibility of the customer to provide safe and reasonable access, and if the driver is not certain that this is the case when he arrives on the site, he may ask you to sign an indemnity form.

If the truck can be positioned at right angles to the job, the reach of the chute is up to 2.5 metres. If the truck can only draw up alongside the job, the maximum distance will be around 1.5 metres.

If you think this is insufficient for your project, we can use a concrete pump to place the concrete up to a distance of around 45m away from the truckmixer. An extra charge for this service will apply.

What are the dimensions of the Keohane Readymix trucks?

6 cubic metres

Overall width - excluding mirrors2542mm
Overall width - including mirrors 3101mm
Overall length8235mm
1st chute pivot to end of 2nd chute2440mm
1st chute pivot to end of 3rd chute1830mm

8 cubic metres

Overall width - excluding mirrors 2542mm
Overall width - including mirrors 3101mm
Overall length 9760mm
1st chute pivot to end of 2nd chute 1983mm
1st chute pivot to end of 3rd chute 2694mm

What preparation do I need to do ?

Before commencing any excavation an assessment of the site is always useful, including location of any services such as ...

  • Buried electricity cables or gas mains
  • Drainage systems
  • Overhead cables for electricity or telephone
  • Overhanging tree branches
  • Tree roots

All organic matter should be removed before setting out the site. Using a combination of pegs, string and spray line-marking paint, mark out the extent of the foundations. If you are laying a concrete base, floors or drives, dig out the area to twice the required depth of concrete (a minimum of 100mm of concrete is advised, so the area should be dug out to 200mm deep). You should also compact the soil. It is important to ensure that the foundation is level. Then place a sub-base layer of hardcore approximately 100mm deep and compact it to give the concrete a solid base and prevent sinking. Sprinkling a thin layer of sand on top of the hardcore will provide a smooth surface to work with. Laying a sheet of polythene damp proof membrane between the sub-base and concrete will help to stop the concrete from drying out too fast, and will also help to prevent rising damp on the finished project.

What tools do I need ?

It is likely that, if you are a gardener or diy-er, you will already have the tools required for the job, but it’s worth double-checking before the delivery arrives to make sure you have everything you need.

  • Tape measure - to measure your site and calculate how much concrete is required.
  • String and pegs - for marking out the area you need to fill with concrete.
  • Timber - to make pegs and formwork, and to use as a tamping beam.
  • Wheelbarrow - handy for moving the concrete around the site.
  • Shovel - to help move the concrete
  • Rake - to help move the concrete
  • Spirit level - to ensure the job is level and maintain accuracy.
  • Float or trowel - for surface finishing.
  • Brush - to help you clean up after the job.

What protective clothing is required ?

It is important to be aware that concrete is both abrasive and alkaline, it can cause skin irritation and burns and therefore you will need protective clothing. When placing concrete, full length shirts and trousers should be worn, along with rubber boots and gloves. Eye protection should be worn in case of splashes.

What should I expect when the concrete is delivered ?

The first thing the driver will do when he arrives on the site will be to assess the required delivery location, and establish the most suitable means of discharging the concrete into place. If the driver cannot get the truckmixer close enough, and you have discussed this likelihood with us at the time of ordering, off-loading directly into wheelbarrows will be possible.

How long will the truckmixer wait on site before a waiting charge is made ?

If the truckmixer is required on site for more than 30 minutes, a small additional charge may be applied.

What’s the best way to handle and move the concrete ?

You should minimise the manual handling of concrete by ensuring that the truckmixer is as close as possible to its final location. The less you move it, the better. Start pouring the concrete in a corner and work away from it. Ensure that you use the correct tools, such as a square-nosed shovel or concrete rake. Using the wrong tools can cause segregation.

How long do I get before the concrete sets ?

Once the concrete arrives on site, you will normally only have between 1 and 2 hours to place, level and compact the concrete and to finish the surface.

Why is compaction so important ?

Compaction ensures the optimum density of the mix is achieved, increasing compressive strength. Where reinforcing is used, the bond between concrete and redistribution bar is improved. Permeability of the concrete decreases, decreasing cold joints, honeycombing entrapped air and segregation.

Do I need to introduce controlled contraction joints ?

Movement of the concrete slab caused by changes in temperature and drying shrinkage can be minimised by the introduction of controlled contraction joints. Contraction joints create weakened sections in the slab to help control crack locations. Joints are neater in appearance and can be sealed and require less maintenance than uncontrolled cracks. Jointing should be planned with large floor slabs divided into smaller rectangular sections. Avoid sharp angles and be aware of changes in thickness of the slab. Concrete which is 100mm thick should be jointed every 3 to 4 metres. Joints should be cut to a minimum of a quarter of the slab thickness.

What curing techniques could I use?

Curing concrete enables it to reach its designed compressive strength, making the material more durable. To cure correctly, concrete requires sufficient moisture content, a favourable temperature between 10 to 20 degrees centigrade, and time to reach its specified strength (a minimum of 7 days to reach 70%).

Methods of curing:

  • Sprinkling or fog spraying, keeping the surface continuously damp (alternate wetting and drying can cause cracking)
  • Covering the concrete with wet hessian, straw, sawdust or sand (avoid materials that may cause discolour in the concrete)
  • Covering the concrete with plastic sheeting (white in hot weather, black in cold weather)
  • Use curing compounds (avoid using if the surface is to be painted or ant other surface cover)

How can weather conditions affect the concrete ?

If the weather is particularly hot or windy, slump loss will increase making the concrete difficult to handle. In addition, the concrete set will accelerate, decreasing the handling time. If water is added to the mix to offset slump reduction, a reduction in strength may occur and shrinking and cracking may occur. To counteract this, we may be able to add a water replacement or retarding agent, so contact us if you are concerned about your delivery. You can also shade the concrete from direct sunlight and protect it with wind breakers. Finally, you could apply curing techniques immediately after finishing.

If the weather is particularly cold, this will increase the setting time of the concrete and retards the concrete stiffening. In addition it will slow down the concrete strength gain. Freeze-that can damage the concrete. By increasing cement contents, using a different cement or adding an accelerating admixture, we may be able to help prevent some of these symptoms. If possible, keep the concrete at a temperature above 10 degrees centigrade by insulating or heating, and protect the concrete with windbreakers. Finally, as a final note of advice, try to avoid laying concrete in temperatures below 5 degrees centigrade.

I have a question which is not answered on this web site - what do I need to do ?

Click here for details on how to contact us.

 

Every effort is made to ensure the accuracy of all textual and pictorial content on this web site. No charge is levied for the advice contained within this web site and accordingly the company, its employees and authorised agents can accept no liability whatsoever, either directly or indirectly arising from the use of its products in connection with any information or advice contained in this web site.

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