Tuesday, 3 June 2014

Step 5 - Making the foundations - Designing and testing the quality of the concrete.



Testing the quality of the concrete.. 

Throughout the project, we will use huge amounts of concrete. Concrete is made up of a number of materials and these materials can be adjusted in quantities to give the concrete various properties. These properties could be in its eventual strength, in the way it flows, the speed it drys and even in its ability to resist water.

Getting this concrete mix right is essential - The ultimate strength of the building depends on it!

Like making a less than yummy cake?
The first stage of this journey is the design of the concrete mix, this is a theoretical design of the various components that might be used to make the concrete, sort of like making a huge, very unpleasant tasting cake!

This trial mix is then made and put through a number of test before being selected for the project.




Throughout the project , whenever concrete is delivered to site the same tests are done to ensure that the concrete delivered is the same as the concrete trial mix that was done at the start of the project...

A sample of the concrete delivered  to site and used in any construction is stored and labelled in these steel boxes 15cm x 15cm for later testing




After a few weeks it is then sent to a special outside lab for testing on its composition and also its compressive strength.......














Here is an example of the concrete test certificate, this one is from the grade 40 concrete for the raft, around 2 days from casting, you can see it is nearing 70% of its strength as it progressively dries.



The concrete also goes through a slump test before it is allowed on the site. This very simple test is designed to quickly check that the concrete does not have a too high water content as this would ultimately affect the ability of the concrete to chemically react and harden properly...





UPDATE: Here are some example of the tests of the concrete from the foundations