Table of Contents
M20 Concrete at First Glance Nominal Mix = 1:1.5:3 represents volumetric proportions = 1 part cement: 1.5 parts sand : 3 parts aggregate Characteristic strength = 20 MPa at 28 days Common Uses = Used for PCC and RCC works for small to medium structures. ( Not suitable for heavy structures ) Maximum water-cement ratio = For RCC, the listed limits are 0.55 for mild, 0.50 for moderate, 0.45 for severe and very severe, and 0.40 for extreme exposure.1 IS Code = IS 456:2000 |
In the field, I used to suggest using the M20 concrete ratio for small to medium-sized structures for cost control1. For RCC work, I suggest using M20 or richer grade only.
For heavy structures like a dam, high-rise buildings, airport construction, highway construction, and other similar construction, I mostly suggest using M25 or richer concrete grade according to the mix design.
1. Calculate Cement, Sand & Aggregate for M20 Concrete
2. M20 Concrete Ratio – Overview
Concrete having a characteristic compressive strength of 20 MPa after 28 days of curing is known as M20 concrete.
The nominal volumetric proportion of M20 concrete ratio is 1:1.5:3. It indicates the cement : sand : aggregate ratio. It simply means that if 1 part of cement is used for making concrete, you should use 1.5 parts of sand and 3 parts of aggregate.2
✔ In M20 concrete,
“M” denotes the concrete mix ratio of cement:sand: aggregate & “20 “Stands for Compressive Strength @ 28 Days in N/mm².
| Code | IS 456:2000 (Table 9 and Table 5) |
| Ratio | 1:1.5:3 |
| Compressive Strength | 20 MPa { Note: MPa = N/mm²} |
| Uses | Used in RCC works like; a. Rigid Pavement Construction b. Used to construct structural members like slabs, beams, columns, etc. (for small to medium structures only. Not suitable for heavy structures). c. Retaining structures, piles, etc. |
| Grade Category | Normal Grade ( Nominal Mix ) |
| Required Water-Cement Ratio | For RCC, the listed limits are 0.55 for mild, 0.50 for moderate, 0.45 for severe and very severe, and 0.40 for extreme exposure.1 |
3. M20 Concrete Ratio Uses
This concrete grade is commonly used for small- to medium-scale constructions. Some common uses of the M20 Concrete Ratio are:
✔ Used in the construction of Residential Buildings, Pavements, Footpaths, Garden Paths & light-duty industrial floors.
✔ Used to construct piles and other general RCC structures.
✔ Used to build retaining walls, buildings, landscaping & architectural designs.
4. Cement Sand Aggregate Calculation For 1 m³ M20 Concrete Ratio
Data per 1 m³ of M20 Concrete Ratio
| Material | Volume Required (m3) | Materials Required in kg |
| Cement | 0.28 | 403.2 |
| Fine Aggregate | 0.42 | 619.85 |
| Coarse Aggregate | 0.84 | 1359.82 |
| Water | 0.190 | 190 kg ( Average ) |
| Things To Know!!
Density of Cement = 1440 kg/m3 Density of Sand = 1450-1500 Kg/m3 Density of Aggregate = 1450-1550 Kg/m3 Weight of Cement in 1 Bag = 50 Kg Volume of 1 Bag of Cement in Cubic meter = 0.03472 m3 |
Now, Taking
Grade of Concrete = M20 Concrete
Mix Ratio = 1:1.5:3
Total sum of ratio =1+1.5+3 =5.5
Wet volume of Concrete = 1 m3.
Dry volume of concrete = 1 *1.54 = 1.54 m³ ( Dry volume factor = 1.54 )
i. Cement Quantity Calculation
Quantity of cement = (Own Ratio/ Total sum of ratio) * Dry Volume
= ( 1/5.5 ) * 1.54
= 0.28 m³
Cement in kg = volume of cement * density of cement
= 0.28 * 1440
= 403.2 kg
ii. Sand Quantity Calculation
Quantity of sand = (Own Ratio/ Total sum of ratio) * Dry Volume
= ( 1.5/5.5 ) * 1.54
= 0.42 m³
iii. Aggregate Quantity Calculation
Quantity of aggregate = (Own Ratio/ Total sum of ratio) * Dry Volume
= ( 3/5.5 ) * 1.54
= 0.84 m³
iv. Water Calculation
For inferior-quality concrete: W/C ratio = 0.55
For superior-quality concrete: W/C ratio = 0.45
Water required per m³ = 0.45 * 403.2 = 181.44 kg
| Read Also: Grades of Concrete |
5. How to Prepare M20 Concrete?
We can prepare M20 concrete on site in the following steps:
a. Materials Selection
Choosing cement, sand, water and aggregate based on requirements is the first step. You can choose cement of 33, 43, or 53 grade as per requirement. Aggregate of size 20mm or smaller is commonly used for M20 concrete. Sand passing through the sieve of 4.75 mm is
b. Batching
Nominal mixes are given by volume. So, the M20 ratio represents 1 part cement : 1.5 parts sand : 3 parts aggregate by volume.
c. Mixing of Materials
We can perform hand mixing or machine mixing based on suitability. Hand mixing may result in improper mixing, so my first choice is machine mixing.
d. Transportation & Placing
Transporting of concrete should be done using an iron pan, wheelbarrow, or concrete pump. Then, concrete is placed in the desired place.
e. Compaction of Concrete
Freshly placed concrete should be compacted with vibrators. The main aim of compaction is to remove air bubbles or air voids.
f. Finishing of Surface
After concreting, the rough concrete surface is levelled and smoothed during the finishing process.
g. Curing of concrete
Curing is done to support the hydration reaction of concrete that results in high strength of concrete.
6. How strong is M20 Concrete compared to other grades?
Based on the strength of concrete, I have prepared this table comparing it with other concrete grades.
| Concrete Grade | 28-Day Strength (MPa) | Compared to M20 |
| M7.5 | 7.5 MPa | 62.5% Weaker |
| M10 | 10 MPa | 50% Weaker |
| M15 | 15 MPa | 25% Weaker |
| M20 | 20 MPa | Base Grade |
| M25 | 25 MPa | 25% Stronger |
7. Frequently Asked Questions
a. Which standard is followed by the M20 Concrete Ratio?
Ans: M20 Concrete Ratio follows IS 456:2000 ( 2005 Reaffirmed): Plain and Reinforced Concrete – Code of Practice.
b. What is the commonly used water-cement ratio for M20 concrete?
Ans: For M20 Concrete, the commonly used water-cement ratio is 0.50.
c. What is M20 concrete?
Ans: It is a concrete having a compressive strength of 20 MPa (20 N/mm²) after 28 days of curing and prepared by using 1 part cement, 1.5 parts sand, and 3 parts aggregate.
d. What is the mix ratio of M20 concrete?
Ans: The mix ratio of M20 Concrete is 1:1.5:3.
e. What is the strength of M20 concrete?
Ans: M20 concrete has a compressive strength of 20 MPa (20 N/mm²).
f. Where is M20 concrete used?
Ans: It is used to construct structural members like slabs, beams, columns, etc. (for small to medium structures only; not suitable for heavy structures or work).
g. Is M20 concrete suitable for RCC?
Ans: Yes, M20 concrete is suitable for RCC work. ( For small to medium structures )
h. How many cement bags are required for 1 m³ of M20 concrete?
Ans: 8.064 bags ( 403.2 kg ) of cement (50 kg each) are required to produce 1 cubic meter of M20 concrete.
i. Can M20 concrete be used for house construction?
Ans: Yes, it can be used for construction of house.
j. How long does M20 concrete take to gain full strength?
Ans: Like M20 concrete, all concrete grades need around 28 days to gain full strength.
| Written By | Madhu Krishna Poudel |
| Role | Construction Site Supervisor | Founder, DreamCivil |
| Experience | 8+ years of practical construction experience |
| Technically reviewed by | Er. Bikas Kafle |
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