Different concrete grade / concrete mix

 There are two type of mix design :

1. Nominal Mix design (For below M20 grade)
2. Design Mix (For above M20 grade)
M stands for Mix and numerical value 20 stands for Mpa or N/mm2 compressive strength of concrete at 28th day.

According to IS 456:2000 code Up to M20 we will go for nominal mix design, like:

M5=1:5:10
M7.5 = 1:4:8
M10 = 1:3:6
M15 = 1:2:4
M20 = 1:1.5:3
Beyond M20, it needs to do design mix with reference of IS 456:2000

For design mix we can refer to IS:456, IS:10262 & IS:1343, we need to consider the following points :

Workability of concrete.

Consistency of concrete.

Strength of concrete.
Water-cement ratio.
Durability of concrete.
Density of concrete.
Generation of heat of hydration.

Recommended Grades of concrete (based on compressive strength) where can be used – Reference: IS 15658.2006, Table: Paver Blocks for Different Traffic Categories: (Which grade of concrete where to be used):

Important NOTES on the above table:

1. Non-traffic areas are defined as areas where no vehicular traffic occurs.
2. Light-traffic is defined as a daily traffic up to 150 commercial vehicles exceeding 30 kN laden weight, or an equivalent up to 0.5 million standard axles (MSA) for a design life of 20 years ( A standard axle is defined as a single axle load of 81.6 kN).
3. Medium traffic is defined as a daily traffic of 150-450 commercial vehicles exceeding 30 kN laden weight, or an equivalent of 0.5 to 2.0 MSA for a design life of 20 years.
4. Heavy traffic is defined as a daily traffic of 450-1500 commercial vehicles exceeding 30 kN laden weight, or an equivalent of 2.0 to 5.0 MSA for a design life of 20 years.
5. Very heavy-traffic is defined as a daily traffic of more than 1500 commercial vehicles exceeding 30 kN laden weight, or an equivalent of more than 5.0 MSA for a design life of 20 years.

Similarly, based on flexural strength / breaking load of concrete, we can decide which concrete can be used where

Suggested values of minimum breaking load for different applications are given below as per IS 15658:

Pigment for concrete:

Synthetic or natural pigments maybe used in concrete mix to obtain paver blocks with desired shades of colours. The pigment used should result in durable colours of paver blocks, but not contain matters detrimental to concrete. Pigments, either singly or in combination, conforming to the following Indian Standards may be referred:

Floor topping:

Since, concrete is dusty, porous, etc., in nature which makes concrete not to leave it exposed for long time; hence, it is best to seal the top surface using floor topping, coating or at least by applying sealers. A variety of different types of synthetic resin systems are available which can form the binder of a flooring system. These include typically epoxy, polyurethane and methacrylate resins. Different resin types give different combinations of application characteristics and in-service performance and the considerations which affect the selection of a particular type are described as follows (reference: FeRFA_GUIDE_TO_SPECIFICATION_&_ APPLICATION_OF_SYNTHETIC_RESIN_FLOORING):

Note:

LD (Light duty) : light foot traffic, occasional rubber tyred vehicles
MD (Medium duty) : regular foot traffic, frequent fork lift truck traffic, occasional hard plastic-wheeled trolleys,
HD (Heavy duty) : constant fork lift truck traffic, hard plastic wheeled trolleys, some impact
VHD (Very heavy duty) : severe heavily loaded traffic and impact

Next blog explains: How to decide what should be the strength of the floor depending on the load / vehicular movement.

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