Effect of Water Cement Ratio on Strength of Concrete

WHAT IS WATER CEMENT RATIO? The water–cement ratio is the ratio of the weight of water to the weight of cement used in a concrete mix. EFFECT OF WATER CEMENT RATIO ON CONCRETE

A lower ratio leads to higher strength and durability, but may make the mix difficult to work with and form. Work-ability can be resolved with the use of plasticizers or super-plasticizers. However, a mix with a ratio of 0.35 may not mix thoroughly, and may not flow well enough to be placed. More water is therefore used than is technically necessary to react with cement. Water–cement ratios of 0.45 to 0.60 are more typically used. For higher-strength concrete, lower ratios are used, along with a plasticizer to increase flowability.

Too much water will result in segregation of the sand and aggregate components from the cement paste. Also, water that is not consumed by the hydration reaction may leave concrete as it hardens, resulting in microscopic pores (bleeding) that will reduce final strength of concrete. A mix with too much water will experience more shrinkage as excess water leaves, resulting in internal cracks and visible fractures (particularly around inside corners), which again will reduce the final strength.

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How does water cement ratio influence concrete strength?

If the water-cement proportion is higher, it brings about wider spacing between the cement aggregates and thus, influences the compaction. Correspondingly, concrete’s durability and compressive strength are decreased due to increased dampness levels.

How does the water-cement ratio and permeability influence the durability of concrete?

2.3 Concrete Durability The permeability of concrete and the permeability of the paste decreases as the w/c ratio decreases. Low w/c ratio means lower permeability, therfore lower voids in the concrete. This means that it is more difficult for water, and corrosives, to penetrate the concrete.

How does water-cement ratio and gel space ratio affect strength of concrete?

Explanation: Gel space ratio: (i) Since concrete is a brittle material, its porosity primarily governs its strength. The compressive strength is found to be severely decreasing with an increase in the porosity. (ii) The porosity of concrete which governs the strength of concrete is affected by the gel/space ratio in concrete.

(iii) The gel/space ratio is the ratio of the solid products of hydration to the space available for these hydration products. (iv) A higher gel/space ratio reduces the porosity and therefore increases the strength of concrete. (v) The gel/space ratio, which governs the porosity of concrete affecting its strength, is affected by the water/cement ratio of concrete.

A higher water/cement ratio decreases the gel/space ratio increasing the porosity thereby decreasing the strength of concrete. (vi) There is a lot of difference between the theoretical strength of concrete and the actual strength of concrete. Actual strength of concrete is much lower than the theoretical strength (this is the limitation of gel space theory) estimated on the basis of molecular cohesion and surface energy of a solid assumed to be perfectly homogenous and flawless.

How does water-cement ratio affect the setting time?

Concrete mixes with lower water/cement ratios generally have faster setting times. However, these may be harder to work with as they start hardening earlier; thus, it it necessary to do all the finishing operations faster. On the other hand, concrete mixes with higher water/cement ratios have slower setting times.

What is water-cement ratio m10?

water cement ratio for m10 grade of concrete – Ratio of water and cement is known as water cement ratio which is about 34 litre per bag cement for m10 grade of concrete 1 bag cement required = 34 litre of water 66.5 bags = 66.5×34= 2261 litre of water So we have required water consumption in pcc 1:3:6 is approx 2261 litre of water for 100m2 having 150 mm thick slab.

How does water cement ratio affect the properties of hardened concrete?

It was observed that the higher cement-water the higher the strength of concrete. However, the higher cement-water ratio leads to the less density and weight of concrete. In addition, the compressive strength was observed to increase with age of curing days.

How does types of cement can affect the strength of concrete?

The difference between all these types of cements is the rate of hydration and point of application. For example, high alumina cement would provide strength in lesser time as compared to OPC cement, similarly, PPC has tendency to provide strength at later days of curing.

Is a higher water-cement ratio stronger?

UNDERSTANDING SPALLED CONCRETE Time: 05:57 Watch this easy-to-understand explanation of what causes concrete spalling, from concrete expert Chris Sullivan. The water to cement ratio compares how much water versus cement is used in a concrete mix. A low water cement ratio leads to stronger concrete, but is more difficult to work with.

Which of the following are the factors affecting water-cement ratio?

Aggregate / Cement Ratio – Following points must be noted for aggregate cement ratio:

• If the volume remains the same and the proportion of cement in relation to that of sand is increased the surface area of the solid will increase.
• If the surface area of the solids has increased, the water demand will stay the same for the constant workability.
• Assuming an increase in cement content for no increase in water demand, the water cement ratio will decrease.
• If the water cement ratio reduces, the strength of the concrete will increase.

The influence of cement content on workability and strength is an important one to remember and can be summarized as follows:

1. For a given workability an increase in the proportion of cement in a mix has little effect on the water demand and results in a reduction in the water/cement ratio.
2. The reduction in water/cement ratio leads to an increase in strength of concrete.
3. Therefore, for a given workability an increase in the cement content results in an increase in strength of concrete.

What is the effect of reducing water-cement ratio?

By reducing the amount of water, the cement paste will have higher density. However, the reduction of the water content in a concrete mixture should be done in such a way that complete cement hydration take place and sufficient workability is achieved.

Is a higher water-cement ratio stronger?

UNDERSTANDING SPALLED CONCRETE Time: 05:57 Watch this easy-to-understand explanation of what causes concrete spalling, from concrete expert Chris Sullivan. The water to cement ratio compares how much water versus cement is used in a concrete mix. A low water cement ratio leads to stronger concrete, but is more difficult to work with.

Why is water-cement ratio important?

Concrete Specifications – Why Water Cement Ratio: Why Not The water-cement ratio (more correctly water-cementitious ratio) is a criterion for concrete that is very important and governs many of its desirable properties to include porosity, permeability, freezing/thawing resistance, and strength, just to name a few.

So it’s not unexpected that specifications may call for a limit on the maximum water-cementitious ratio (w/cm). But when is a maximum w/cm really required? In accordance with ACI-318-14 Building Code Requirements for Structural Concrete, the requirement for a maximum limit on w/cm is based upon the anticipated in-service exposure conditions of the concrete element where durability is a concern.

The exposure conditions or categories that require a maximum limit on w/cm are:

Category F (freezing and thawing exposure), Category S (sulfate exposure), Category W (exposed to water where low permeability is required), and Category C (corrosion protection from external chlorides)

The corresponding maximum w/cm requirement will be dependent on the degree of severity within each exposure category. Specific requirements can be found in ACI 318-14, Table 19.3.2.1. Also, there is a corresponding minimum compressive strength requirement for each respective exposure category.

If w/cm is so important then why not specify a maximum limit on w/cm for all concrete? The answer is simple; specifying a maximum w/cm when it is not needed comes with unintended consequences. Concrete used in interior applications, such as floor slabs and columns, will not be exposed to adverse environmental conditions and durability is not a concern.

The property that interior concrete must meet is compressive strength, sufficient to satisfy structural loads and/or provide adequate abrasion resistance. Also, interior concrete should be non-air entrained; in fact maximum limits on air content are often imposed on hard-troweled floor slabs.

Non-air entrained concrete will typically require about 1 to 3 gallons more water per cubic yard compared to air entrained although it will have about 500 psi to 1000 psi higher strength at equal cementitious contents than air entrained concrete. Due to the higher water content for non-air entrained concrete an unnecessarily high cementitious content may have to be derived to meet a maximum w/cm limit.

These higher cement contents and ensuing strength levels may be well in excess of that needed to meet structural and/or abrasion resistance requirements. Not only does this needlessly increase the cost of the concrete it can lead to problems with increased drying shrinkage and increased curling potential.

A w/cm commensurate with that needed to achieve the desired compressive strength is all that is needed for non-air entrained concrete. A maximum limit on w/cm only applies to concrete that will be subjected to one or more of the in-service exposure conditions noted above where durability is a concern.

When the concrete will not have an adverse exposure condition in-service there is no reason or requirement for a maximum limit on w/cm. Submitted by Robert E. Neal, Technical Services Engineer with Lehigh Cement Company : Concrete Specifications – Why Water Cement Ratio: Why Not

What will happen if water-cement ratio increases?

Answer (Detailed Solution Below) – Option 1 : b and c Free Free Mock Test Uttar Pradesh (History) 10 Questions 10 Marks 7 Mins Explanation: Water-cement ratio : It is the ratio of the weight of water to the weight of cement used in a concrete mix. The ratio of water-cement is generally lying in between 0.35 to 0.65. The above figure shows that compressive strength is at its peak when the water to cement ratio is low. But as the water-cement ratio is increasing, the strength of concrete is low. Too much water will result in the segregation of the sand and aggregate components from the cement paste.

Water that is not consumed by the hydration reaction may leave concrete as it hardens, resulting in bleeding that will reduce the final strength of concrete. A mix with too much water will experience more shrinkage as excess water leaves, resulting in internal cracks and visible fractures (particularly around inside corners), which will reduce the final strength.

There is a direct relationship between the water-cement ratio and the workability of concrete because as the water content increases, the fluidity of the mix increases so workability increases. Hence, from the above options, option B and C is true. Last updated on Sep 22, 2022 The Uttar Pradesh Power Corporation Limited JE (Civil) 2022 final result has been declared on 10th August 2022.

What is the effect of reducing water-cement ratio?

By reducing the amount of water, the cement paste will have higher density. However, the reduction of the water content in a concrete mixture should be done in such a way that complete cement hydration take place and sufficient workability is achieved.