Do you know how concrete is tested?

I went to structure laboratory this morning to monitor some concrete samples to be tested, concrete testing today was carried out to obtain concrete strength data on the construction work that is being done in the field/location, testing is better known as "concrete compressive strength test".

Concrete samples that we test are cuboid with dimensions of 15 x 15 centimeters and samples taken to the laboratory structure usually amount to 6 pieces or more depending on needs, A material test equipment that we use is a production test equipment from Indotest which has a National Accreditation Committee certificate. Samples concrete to be tested should be dry and have reached a concrete age of about 28 days or can be less than 28 days under certain conditions.

Why does concrete have to be tested?
Actually, every construction planning is done accurately because if it is done carelessly, it can be sure that there will be a planning failure and an impact on the condition of the structure of a building, if the calculation of a structure by a planner is correct then all work carried out on-site will be full responsibility of the contractor.

To anticipate the failure of a structure, a contractor will work in earnest according to the work reference procedures and to support the truth that has been carried out according to the initial design plan, the contractor requires an independent party appointed by the work owner, in this case, the structural laboratory functions as an independent team that issues recommendations related to the construction work.

In certain cases, the structural laboratory is also requested by an inspection team (an authority party) to ascertain whether a structure building that has been done is in accordance with initial planning, this condition usually occurs due to indications of corruption or other things that are considered detrimental to a country.

Imagine that if an initial design concrete was supposed to have K-300 strength but what was done was concrete with K-175 strength? Keep in mind that concrete serves to hold loads vertically and if the concrete is not able to withstand a load then it can be sure the building can not be used, for example, columns that are not able to withstand the load, abutment of the bridge that is not able to withstand a load above it makes the bridge unusable, and many examples fail other structures that can harm others.

How can these conditions occur?
Many things cause the strength of the concrete is not in accordance with an initial design, for example, workers who are not experienced when making concrete aggregates, the concrete composition should be 1: 2: 3 (1 cement: 2 gravel: 3 sand) but implemented 1: 3: 5 (1 cement : 3 gravel: 5 Sand) so that a strength of concrete is certainly different or even not achieved as initial design, the contractor who deliberately reduces a composition of concrete to get more profit (corruption) or unavailability of appropriate construction materials in an area and so forth.

So, how to prevent structural failure?
First thing I recommend is, you should still make concrete in accordance with an initial design, but if you are in doubt then every structural work such as foundations, columns, beams, and concrete slabs should be taken samples and test them in the structure laboratory but if results are concrete that you have made it not in accordance with an initial design, then, my suggestion, please discuss it with structural expert and you may need a new design that supports the strength of concrete that you have been worked or there is also a possibility of concrete that has been installed should be dismantled.

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What is the concrete compressive strength testing process?
1> The concrete cubes to be tested are put in the test equipment, making sure the test equipment is in a zero-pressure condition

^{Officers insert concrete cubes into compressive test equipment, Image source @kharrazi smartphone}

2> After ascertaining the exact position of the concret compressive test equipment is turned on with a certain compressive strength per second.

^{Indicator of concrete compressive strength test value, Image source @kharrazi smartphone}

3> The test concrete sample will be pressed until a pressure value that is acceptable to a test concrete is obtained.

^{Concrete test that has been tested compressive strength, Image source @kharrazi smartphone}
4> The structure laboratory staff records a results of the concrete test and makes a report.

^{Some test concrete samples that have been tested, Image source @kharrazi smartphone}

^{Concrete strength test was completed, Image source @kharrazi smartphone}

Reports issued by the structure laboratory will later help the owner of a work/project to issue recommendations.

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Conclusion
Testing strength of concrete against a compressive strength is very necessary to avoid the construction of structural failure and will be fatal in the future if no testing is carried out, our test aims to determine a type of concrete being worked on-site, whether according to the initial design or not.

Actually, there are still several ways to test concrete and depending on needs such as concrete resistance to pressure, twisting and so forth

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This is all that I can write, thank you for stopping by and staying healthy, see you around.