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Water Cement Ratio

What is Water Cement Ratio?

Water Cement Ratio

Water plays a very important role in making the bond between cement & aggregate. Without water, cement is not able to mix with aggregate. Water should not be added more or less it must be added as per the design of concrete. The water is added with a ratio of cement in concrete is called water-cement ratio. it is denoted by “W/C

What is Water Cement Ratio

Generally, the water-cement ratio is 0.40 to 0.60. If it is below 0.40, the concrete will be hard. Its workability will be less and strength will be more. If this ratio is more than 0.60 its strength will be less but workability will be higher. The water-cement ratio is directly proportional to the workability and inversely proportional to their strength. Workability means the ease of placing and compacting concrete. on construction site workability of concrete is measured by doing a slump test using a slump cone. 

The water-cement ratio is different for achieving different types of strength. For high strength, the w/c ratio must be low. While for high workability w/c ratio must be high. On-site for high slump value, the w/c ratio must be high. While for low slump value the w/c ratio is also low. The slump values are given below for the different type of construction:  


Types of Construction Slump Max(mm) Slump Min(mm)
1 Mass Concrete 80 20
2 Reinforced Concrete v ˅
3 Thin Vertical Sections 100 40
4 Thin Horizontal Sections 150 80
5 Heavy Sections 200 80
6 Beams, Walls, Columns 130 70
7 Road Construction 60 20

The water-cement ratio is also different for different grade of concrete which is given below:

S.No Grade Ratio W/C
1 M5 1:5:10 1.2
2 M7.5 1:4:8 0.9
3 M10 1:3:6 0.68
4 M15 1:2:4 0.64
5 M20 1:1.5:3 0.60

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