The effect of water to cement ratio on the concrete strength
There is an inverse relationship between W/C and strength of concrete.
Dear Dr. El-Awney,
Attached please find the W/C vs concrete strength graph. Figure shows that validity range of water to cement ratio is very limited. Compressive strength is at peak, when water to cement ratio is low. Beginning of the curve depends on the available means of compaction (that is either done with vibrators or manually hand compaction). If large size aggregates is used with low water to cement ratio and high contents of cement then it exhibit retrogression of the concrete strength. A conclusion can be made that if there is a low water to cement ratio in a fresh mix than after hardening, water/cement will not be able to lead higher strength of concrete. These conditions happen because of the development of tensile stresses due to shrinkage and creep. This leads to the cracking of the cement or to the loss bonds (that is between cement and aggregates) as if aggregates try to restrain the tensile stresses. Therefore, low water to cement ratio leads to serious problems in hardened concrete. When water to cement ratio is low in a fresh mix, then less water is available for the hydration of cement.Hence, some amount of cement paste remains un-hydrated that leads to internally tension in concrete plus weak bond.
Dear Saleh,
Usually the increase of the water-to-cement ratio results in decrease of the compressive strength of concrete.
Best regards
Łukasz Sadowski
Dear Doctor with respect
The strength of concrete increase by decreasing the water cement ratio and vice versa the strength decrease by increasing the water cement ratio.
Best regards.
The most important factor that affects the strength of concrete is water-cement (W/C) ratio. Lower the W/C ratio, higher would be the strength of concrete. However, there is a cap on this ratio such as 0.5 (max) and near about 0.2 (min). For complete hydration of Portland cement W/C shall be 0.18 (minimum) whereas the extra water (beyond 0.18 ratio) provides workability to the mix. As the W/C ratio increases, strength of concrete would reduce and so the durability properties. The W/C ratio can be lowered by utilizing water reducing admixtures such as plasticizers (upto 20% reduction in water demand) and superplasticizers (20 to 30% reduction). .
I completely agree with my colleagues, ( Lukasz Sadowski & Taleb Bahmed Ismehen ) about the increase of the water-to-cement (W/C) ratio results in decrease of the compressive strength of cement concrete and vice versa.
Yes, the most important factor that affects the strength of cement concrete is the water to cement (W/C) ratio. The lower the W/C ratio means the higher would be the strength of cement concrete. For complete hydration of Portland cement, the W/C ratio shall be 0.18 (minimum) whereas the extra water (beyond 0.18 ratio) provides workability to the mix. As the W/C ratio increases, the strength of cement concrete would reduce and so the durability performance. The W/C ratio can be lowered by utilizing water reducing admixtures such as plasticizers (Ps) up to 20% reduction in water demand and superplasticizers (SPs) 20 to 30% reduction in water demand).
Dear Dr. Saleh
water to cement ratio controls the compressive strength and workability of concrete, increasing the water/cement ratio will give more workable fresh concrete but with lower strength properties when hardened. another important factor in this issue is the cement content in the mix, you can reduce the water and add additives which retain the workability
Dear Dr. Alireza Joshaghani, Thank you so much for your interesting and valuable comments. For necessary please send me your E-mail as soon as possible.
All the best Regards
Sincerely Yours,
Prof. Dr. Saleh Abd El-Aleem Mohammed
(Applied and Engineering Inorganic Chemistry)
Vice-Dean Faculty of Science, Fayoum University, Fayoum, Egypt
Dear Dr. Saleh,
The water to cement ratio affects two properties : Strength and workability of the concrete.
Once this ratio increases, the compressive strength decreases and the workability rises and vice versa.
So to provide both good strength and workability of the concrete we could add additives such as plasticizer and so on instead of increasing this ratio.
Dear Dr. Basma , Thank you so much for your interesting and valuable comments.
Yes, the water to cement ratio affects two properties : Strength and workability of the concrete. Once this ratio increases, the compressive strength decreases and the workability rises and vice versa. So to provide both good strength and workability of the concrete we could add additives such as superplasticizer .
As well known, concrete strength decreases with increase in w/c ratio but to balance other equally important factors such as compaction, the amount of water has to be gauged such that compaction is still effective. This is more so where superplasticiser is not used.
Dear Doctor I agree with my colleagues ideas, about. Increasing water to cement ratio decreases compressive strength. And which may affect in the near future of the building durability.
Dear Dr. Saleh, Thank you so much for your for sharing
Best wishes,
There is an inverse relationship between W/C and strength of concrete.
I agree with my colleagues, the comressive strength of concrete deceases with the increasing of W/C.
Regards
The decrease of the compressive strength of concrete results in increase of the W/C ratio.
Decreasing of W/C ratio increases the compressive strength of concrete. Minimum water content required by the mix gives maximum strength.
Best regards.
This is what has become known as the Abrams' law (also called Abrams' water-cement ratio law) in civil/concrete engineering. The law states the strength of a concrete mix is inversely proportional to the mass ratio of water to cement. As the water content increases, the strength of concrete decreases.
In current research on ultra-high performance and high strength concrete is produced with very w/c (0.20 to 0.3), therefore for achieving desired or sometimes high slump, new generation superplasticizer called high-range water reduces are used as admixtures. Such concrete can achieve 100 MPa or more
w/c reversely proportion with strength and the lowest value can be used without admixtures is 0.25 to 0.30 (the minimum value required for water to complete the hydration process) and highly dependent on the method of compaction, whether mechanical or manual.
The low water to cement ratio in a fresh mix than after hardening, water/cement will not be able to lead higher strength of concrete. These conditions happen because of the development of tensile stresses due to shrinkage and creep. This leads to the cracking of the cement or to the loss bonds (that is between cement and aggregates) as if aggregates try to restrain the tensile stresses. Therefore, low water to cement ratio leads to serious problems in hardened concrete. When water to cement ratio is low in a fresh mix, then less water is available for the hydration of cement.Hence, some amount of cement paste remains un-hydrated that leads to internally tension in concrete plus weak bond.
Yes, the most important factor that affects the strengthening properties of concrete is water-cement (W/C) ratio. Lower the W/C ratio, higher would be the strength of concrete. However, there is a cap on this ratio such as 0.5 (max) and near about 0.2 (min). For complete hydration of Portland cement W/C shall be 0.18 (minimum) whereas the extra water (beyond 0.18 ratio) provides workability to the mix. As the W/C ratio increases, strength of concrete would reduce and so the durability properties.
low water to cement ratio leads to serious problems in hardened concrete. When water to cement ratio is low in a fresh mix, then less water is available for the hydration of cement.
Very useful and interesting discussion, thanks to all.
Yes, W/C ratio adversely affect one of the compressive strength of concrete.
Generally, higher water cement ratio decreases the compressive strength of concrete and vice-versa.
Although higher water to cement ratio accelerates the hydration of cements. But the excess volume of water equates to more space and therefore more porous microstructur, which supports decrease in the strength of concrete as stated above. Porosity is inversely proportional to compressive strength.
http://waset.org/publications/6818/effect-of-water-cement-ratio-w-c-on-mechanical-properties-of-self-compacting-concrete-case-study-
Dear Dr. Saleh
The strength of concrete increase by decreasing the water cement ratio
Strength have inverse relationship with w/c ratio. Increase in W/C ration decrease the strength and vice versa
Simply inversely proportional, the more the water cement ratio, the less the compressive strength.
The water to cement (w/c) ratio affects the 2 properties of concrete: Strength and workability. Care should be taken while selection of w/c ratio for aggressive environment specially in marine environment.
Respective Sir , water / cement ratio should be fixed in particular range. But more water is required for perfect hydration after partial solidification of concrete or mortar neither we will see cracks and voids which decrease the strength of materials. Thus curing is essential part of cement hydration , specially for OPC as compare to Blended cement.
compressive strength will be increased by reducing water to cement ratio.
and it would be harder to place concrete
Agreed with Mahdi. There has to be a balance between strength and workability. Superplasticizers may be used to enhance workability, if the water would need to be reduced greatly.
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