Concrete is one major construction material throughout the world. In fact only less than 10% of construction projects do not involve concrete. It has gained its wide acceptance due to the ease of forming it into desired shapes, sizes and strength -including other physical properties like density and water repulsion. Concrete is only good in compression, hence the use of steel reinforcement (making it reinforced concrete) to cater for tensile forces (including moment and torsion) acting on the structural member.
Reinforced concrete is mostly graded in terms of strength. During design of structural members, the grade of the concrete is factored in. The sizing of these members are dependent on this grade (and some other variables). It is safe to say that the lower the grade of the concrete, the larger the elements will be and the larger the ones that will carry them (and the larger the ones that will carry them and you can put that on repeat).
Picture this; the larger the slabs, the weightier they become, therefore requiring larger sections of beams to transfer their loads to the columns which must also be large enough to not buckle as the loads are transferred to the foundations…and so on….this results into a very bulky building.
Now can’t we save ourselves the stress, save our earth the load and be more energy conservative? Yes we can, and here’s a simple (but of great significance) way -increase the grade of your concrete. By doubling the grade of your concrete and keeping all other things the same, you can comfortably reduce the size (volume) of your beam, and thereby its weight by a whooping 36.1% (actually even more).
Now who doesn’t want a slimmer design? Slimmer designs look more elegant, less bulky, affording more space and, yes, lighter. By reducing 35% of your building weight you don’t need to be told that you’re exerting less load on the tectonic plates. You’re also reducing the amount of energy expended in the construction as the energy required is almost the same for different grades of concrete (now that volume is reduced, energy is also reduced drastically). Time is also better managed. On cost, I would simulate the cost implication of doubling the concrete grade (for this I did on weight, I increased the grade from 30 N/mm2 to 60 N/mm2).
Advantages of using high grade concrete is not limited to reducing weight, it also;
- Ensures more homogeneous members thereby improving their stiffness.
- Resists unexpected impact (perhaps in case of a natural disaster).
- Provides better guarantee of quality and safety.
- The water absorption rate is also reduced.
Now it’s up to you. As I work on the cost implications of improving concrete grade (I’m sure it would cost more and I’m guessing it would be worth it), let me know which one it is for you. Greater strength or weight?