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## Maximum Permissible Quantity of Water Per 50kg of Cement For M20 as Per IS 456

Alternative Question: **Quantity of water needed per 50 kg bag of cement for M20 grade of concrete**

Important ingredient of concrete is cement, sand and gravel have almost same materials density, generally cement, sand and aggregate are mixed in the ratio of 1:1.5:3 (1 part cement to 1.5 parts sand & 3 parts aggregate **by volume**) to achive 20 MPa **strength of concrete** and water should be added in the range of 55% of weight of cement in mild exposure condition for M20 concrete.

### How do You Calculate Water For M20 Concrete?

Water for M20 concrete has been calculated in following steps:-

#### Wet Quantity of Nominal Mix

● Assume wet quantity of nominal mix of M20 concrete is about 1m^{3},.

**Dry Volume of Concrete** = 1× 1.54 = 1.54m^{3}.

### Cement Quantity Calculation

● Calculate part of cement in mix,

Sum of proprtion = 1 + 1.5 + 3 = **5.5**

**Quantity of Cement** = 1/5.5 of dry volume

● Calculate required cement quantity

**Quantity of Cement in Kg** = 1/5.5 × 1.54 × 1440 kg/m3 = 403kg

● Calculate required quantity of water

0.55 is w/c ratio for M20 concrete, so quantity of water required for 1m3 of nominal mix of m20 concrete is about 240 litres, maths calculation such as 403 × 0.55 = 220 litres.

**As per IS456 code book**, in **mild exposure condition** w/c ratio for normal mix of **M20 concrete** is about 0.55, so for a 50kg bag of cement water required is about **28 litres**.

Maths calculation such as water quantity = (220 ÷ 403)× 50 =

28litres.

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#### Maximum permissible quantity of water per 50kg of cement for m20 as per IS 456 for mild exposure environmental conditions

Maximum quantity of water needed per 50kg bag of cement for nominal mix of M20 grade of concrete is about 30 litres on mild exposure environmental conditions. Maths calculation such as maximum w/c ratio is 0.60, water quantity for 403kg cement = 403× 0.6 = 240 litres, so water required per 50kg cement = (240÷403) × 50 = 30 litres.

#### Maximum permissible quantity of water per 50kg of cement for m20 as per IS 456 for extreme exposure environmental conditions

Minimum quantity of water needed per 50kg bag of cement for nominal mix of M20 grade of concrete is about 20 litres on extreme exposure environmental conditions. Maths calculation such as minimum w/c ratio is 0.40, water quantity for 403kg cement = 403× 0.4 = 160 litres, so water required per 50kg cement = (160÷403) × 50 = 20 litres.

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