Concrete’s durability depends on the mixing process. Without compressive strength the slabs become weak. To increase concrete slabs strength, many factors need to be considered. First, have a look at some of the processes that take place when mixing to increase the strength of concrete slabs. Two processes sometimes bring about confusion during concrete slab mixing, these are;
1. Thickening the Mixture to Increase the Strength of the Concrete Slabs
Once the concrete has been set it needs to be stiffened. This may not be in fluid form but still, the slab is not yet dried and is very weak. The setting is done to increase the strength of concrete slab hence reducing the formation of ettringite and calcium silicate hydrate.
2. Fortifying the Mixture to Increase the Strength of the Concrete Slabs
This involves strength and growth which may vary by weeks or even months after the concrete slab has been mixed and placed.
At this stage where the formation of calcium silicate hydrate takes place. On the other hand, cement used undergoes hydration, that’s when hardening comes in.
Factors That Affect Increased Strength in Concrete Slabs
Many factors affect the strength of concrete slabs, some of them are as follows.
- Concrete porosity – When concrete is mixed and placed, voids are created which can be filled with air or water. These pores created, make the concrete very weak. The source of porosity in concrete slabs is attributed by the ratio of water to cement.
- Water to cement ratio -This mix is referred to as the mass of water divided by the mass of cement. It mixes when the water is greater than approximated, the cement ratio hydrates to form products. When the ratio is high some spaces are created and occupied by excess water which turns into pores as soon as the concrete dries.
When the water-cement ratio increases so will the porosity of cement paste in the concrete. This will lead to a decrease in concrete compressive strength.
- The soundness of aggregate -The aggregate used in preparing concrete should not be weak. Example of such aggregate is chalk which is unsuitable for concrete slabs.
- Aggregate-paste bond -In strengthening concrete slabs the integrity of bonding between paste and aggregate is crucial. The bond will determine the effectiveness present which will in turn get rid of voids.
- Parameters related to cement -The strength of concrete slabs can also be as a result of proportions of minerals in the cement. Some of the minerals include,
- Alite content
- Alite and belite reactivity
- Cement sulphate content.
The following are some of the methods used to increase strength in concrete slabs
These are substances that are added to concrete so that it can achieve its properties. To increase the strength of concrete slabs, admixtures are added to concrete, aggregate, water and cement just before or during the mixing process. Click here for more detail about admixture.
Admixtures are categorized into two, chemical admixtures and mineral admixtures. Chemical admixtures are the key to strengthening concrete slabs as they modify almost all the properties of hardened concrete.
The quality of concrete is improved during mixing, transportation and also during placement and curing.
Through pollozanic or hydraulic activity, the nature of hardened concrete is affected.
Increased strength of concrete slabs can also be affected positively and negatively. Cement can be an attributing factor to all these effects there, before, there should be a balance when mixing. If the right proportions are used and followed to every small detail then the strength of slabs will be achieved.