A civil engineer must know how to select the type of concrete.
Choosing a suitable quality of concrete can also be called choosing the right quality characteristic strength of concrete is a demanding task. Furthermore, it is also necessary to select the correct concrete thickness for economical planning.
As we know, the strength of concrete, reinforced steel and transverse dimensions, etc. are the main factors that affect the load capacity of the element. Therefore, we need to select the correct/suitable concrete thickness.
Let's discuss how to choose the quality of concrete. This discussion is based on British Standards .
Firstly, the BS 8110 standard is used for the construction of concrete structures, the selection process can be described as follows.
- Adequacy of deformation to the limit state (SLS and ULS)
- Shelf life requirements (as specified in BS 5328-1:1997 and BS 5328-2:1997)
- Other special requirements.
BS 8110 and BS 5328 take durability requirements into account when determining the concrete required for the structure and select the cement content and water-cement ratio accordingly.
However, later developments of standards (Eurocode 2, BS EN 206, etc.) take into account more detailed durability requirements when specific to concrete.
The choice of concrete thickness depends on the loading conditions of the structure.
The evolution of British Standards provides a more precise answer to the question “How do I choose the quality of concrete?” Let's look at what standards are available for specifying concrete.
- For durability and resistance to limit state requirements, reference is made to the basic Eurocode 2 standard.
- BS EN 206:2013 – Concrete – Specification, performance, manufacture and compliance.
- BS 8500-1:2015+A1:2016 is a British standard complementary to BS EN 206.
Let's look at the new British Standard guidelines (BS 8500-1:2015+A1:2016) for concrete specification.
- First, determine the exposure conditions to which the structure will be exposed. Accordingly, determine the exposure class from Table A.1 of BS 8500-1:2015+A1:2016.
- Additionally, see Table A.2 for aggressive chemical environment exposure classes for concrete (ACEC). ACEC grade is selected based on sulfate content, magnesium content, and pH when these chemicals are observed in groundwater.
- The concrete quality, water-cement ratio and cement content for a service life of 50 and 100 years are presented in Table A.4 and Table A.5, respectively. These tables only apply to concrete with a maximum aggregate size of 20 mm.
- The selection of concrete depends on the exposure class and the nominal performance of the reinforcement.
- In this procedure, Table A.6 – Types of cement and combinations, Table A.7 – Minimum cement content and combinations with maximum aggregate sizes other than 20 mm,
To better explain the process of selecting the type of concrete, cement content, water-cement ratio, cement/cement combination and minimum cement content in accordance with BS 8500-1:2015+A1:2016, the table can be consulted Following.
