What is Water Cement Ratio And How To Calculate Water Cement Ratio
What is Water Cement Ratio?
The water cement ratio compares how much water vs cement is used in a concrete mix. A low water-cement ratio leads to stronger concrete but is more difficult workability.
Water Cement Ratio means the ratio between water weight to the weight of cement used in the concrete mix. Usually, the water-cement ratio falls under 0.4 to 0.6 as per IS Code 10262 (2009) for nominal mix (M10, M15 …. M25)
Water cement ratio of 0.40 to 0.60 are more commonly used. For higher-strength concrete, lower ratios are used, along with a plasticizer to increase flowability. Too much water will result in the segregation of the sand and aggregate components from the cement paste.
Importance of Water Cement Ratio
The water-to-cement ratio is important because it controls the mechanical properties and durability of hardened concrete. When problems occur and/or non-compliance with the specification is suspected, it is often desirable to determine the water-cement ratio.
How to Calculate Water Cement Ratio
The water-cement ratio can be calculated by dividing the water in one cubic yard of the mix ( in pounds) by the mix’s cement (in pounds). So if one cubic yard of the mix has 235 pounds of water and 470 pounds of cement- the mix is a .50 water to cement ratio.
If the mix lists the water in gallons, multiply the gallons by 8.33 to find how many pounds there are in the mix.
Importance of Water, Cement Ratio, and Concrete.
Concrete contains components such as cement, coarse aggregate, sand, aggregate, and water in properly estimated proportions.
This proportion is achieved either as a nominal mix or by a design mix. All the materials have specific properties and important to contribute to the strength of the concrete mix.
Cement is used as a binding component in concrete due to the best adhesive and cohesive property, While water is the cheapest and most important ingredient of concrete way.
When these two-materials air mixed, a chemical reaction takes place named hydration; hydration reaction produces a sticky and thick gel with a binding property on which binds all aggregate in the form of duff and strong material.
Therefore, cement and water both are responsible for binding all elements of concrete together.
Cement and water are used for their ratio called water-cement ratio. The water-cement ratio is defined as the ratio of the weight of water to the weight of cement.
Why do you need to add sufficient water to the concrete mix?
Technically is per studies, Cement requires 23% of water for the hydration process and 15% for expansion of pores and volume increments; thus, 38 percent of the water by weight of cement is a minimum and should be a must.
It has been found that for complete hydration of cement paste and no capital, a report is to be left their sufficient water is required in the concrete mix.
The least amount or quantity of this water corresponds to a 0.38 water-cement ratio. Thus, if the water-cement ratio is less than 0.38, complete hydration is not possible.
If it is more than this, the concrete mass becomes porous and permeable, and if it is less concrete, it becomes dry and harsh and may not find and develop full strength.
For workability consideration, this water-cement ratio is found to a 0.4, but its selection will depend on the requirement of workability of concrete in different conditions, exposure, and nature of work.
Normally at a water-cement ratio of 0.4, the mix has sufficient water for hydration as well as for providing in the concreting process, like mixing, placing, transporting, and compacting because water works as a lubricant in the concrete mix and reduces the internal friction between particles of concrete at this water-cement ratio, the gel formed is in good physical structure and dense.
At a higher water-cement ratio, the gel formed is in a poor physical structure, creates voids during subsequent evaporation, and becomes more porous, resulting in lower concrete strength at a later age.
Calculation of Water Quantity for Concrete Mix.
When you need to calculate the quantity of water for the concrete mix, find the cement content for the volume and water-cement ratio. If we assume 80kg of cement for concrete mix on water-cement ratio. A 0.45, then the required water quantity for 80 kg cement will equal 36 liters.
The effective water-cement ratio on workability.
The workability of concrete means the concrete’s ability to perform concrete in the process like mixing, transporting, placing compacting with ease, and without any segregation.
In other words, the workability of concrete indicates the ability of concrete to works easily.
The water-cement ratio is also an important consideration for the workability of concrete. A high water-cement ratio leads to higher workability because inter particle lubrication is increased.
Similarly, a lower water-cement ratio leads to lower workability because there is a lack of interparticle lubrication. This may lead to pours of concrete water.
The cement ratio varies from 0.4 to 0.7, depending on the exposure condition. A ratio of less than 0.4 will make concrete very stiff if superplasticizers are not used. A ratio of greater than 0.6 makes it sweat and weak concrete way and perhaps leaking concrete, leading to corrosion in the future.
Using a low water-cement ratio is the usual way to achieve high strength and high-quality concrete. Still, the water-cement ratio alone does not generate the required strength of concrete.
Good concrete results from a good mix design and a low water-cement ratio are very empirical parts of a good mix design.
The higher the water-cement ratio means the higher quantity of water, which results in dilution and cement paste.
It makes pour concrete mix and increases water and permeability, thus leads to leakage and dampness.
The effective water-cement ratio on strength.
The compressive strength of the concrete mix is a major characteristic of the concrete mix change in the amount of water that changes concrete strength.
If water is used in more quantity, it may develop more voids e and develop honeycomb structure to a large extent in set concrete.
It results in a decrease in density, durability, and strength. Lower the water-cement ratio, the greater the strength of concrete
Reasons why a high-water cement ratio is not recommended.
- Chances of segregation and bleeding
- Lessens the Ability.
- Development avoids
- The decrease in the strength of concrete.
- The decrease in the life of the structure.
- Leakage and chances of corrosion.
- Increased carbonation due to voids and hence reduced life.
- The freeze-thaw effect, etcetera.
Major reasons why the low water-cement ratio is recommended.
- One increase in strength
- Increase in durability.
- Lower permeability
- No leakage or dampness.
- Greater freeze-thaw, durability
- Better bond with reinforcement