In this article, we will learn the different methods for Grade of Concrete M15 Prepared at the construction site. The concrete which is prepared at the site is known as Cast in situ concrete. As per IS 456-200, Nominal Mix such as M5, M7.5, M10, M15, M20. and above M20 Grade of concrete is known as Design Mix.

There are two different methods to measure the Concrete ingredients i.e. volumetric batching and weigh Batching. In this article, we will learn to prepare the Grade of concrete using volumetric batching. (Measuring Box i.e. Farma in Hindi).

The standard Dimension of Measuring Box = 1 feet x 1 Feet x 1 Feet 3 inch (1′ x 1′ x 1.25′)

Volume of Measuring Box = 1.25 Cft =** 0.03539 cum.**

Now let’s find the Volume of 1 Bag of Cement.

Density of Cement = 1440 Kg/m^{3}

Weight of 1 Bag of Cement = 50 kg

**Volume of 1 Bag of Cement = Weight of 1 Bag of cement /Density of Cement**

= 50/1440 **= 0.03472 m ^{3}**

As we know 1 m^{3} = 1000 Liters.

Therefore Volume of 1 Bag of Cement = 0.03472 x 1000 **= 34.72 Liter. **From a Particle point of view, we consider the volume of 1 Bag of cement = 35 liters.

Hence Volume of 1 Bag of Cement is equal to Volume of measuring Box.

Let’s make the Nominal Mix of M 15 Grade of Concrete.

The ratio of the Proportion of Grade of Concrete is 1:2:4. Where 1 is the part of Cement, 2 is the part of Fine Aggregate (sand) and 4 is the part of Aggregate.

Proportion of M 15 Grade of Concrete in terms of Liters

Cement = 1 x 35 liters = 35 Liters.

Sand = 2 x 35 Liters = 70 Liters.

Aggregate = 4 x 35 Liters = 140 liters.

** M15 Prepared At Construction Site in terms of Measuring Box**

Cement = 1 Measuring Box = **1 Bag of Cement.**

Fine Aggregate (Sand) = **2 Measuring Box or 2 Farma.**

Coarse Aggregate = **4 Measuring Box or 4 Farma.**

Consider the Water Cement Ration for this Grade of Concrete is 0.52.

Amount of Water shall require = Water Cement Ratio x Weight of 1 Bag of Cement.

Amount of Water shall require = 0.52 x 50 = 26 Liters for One Batch of concrete i.e. One bag of cement.

**Following steps to follow for placing the ingredients into the Rotating Drum of the Concrete Mixer.**

- Clean and splash cement slurry on Rotating Drum.
- Place about 12 liters of water in the drum
- Pour 4 Measuring Box of Coarse Aggregate in mixer followed by 2 measuring box of sand.
- Add the remaining water and then Place one bag of Cement in the drum.
- After pouring the ingredient, Rotating Drum shall be revolved about 2 to 3 minutes to get uniform mixing.

**Advantage of Using Measuring Box**

- Produced concrete has a uniform proportion of Ingredients hence it maintains the Quality.

**Disadvantage of Using Measuring Box**

- There is a possibility of adding or Substracting an extra one or two Measuring Box due to less number of Measuring Box required to produce One batch of Concrete.

** ****M15 Prepared At Construction Site** using Mortar Pan

**M15 Prepared At Construction Site**using Mortar Pan

In this method, we measure the Sand and Aggregate using Mortar Pan. As per my experience; 4 Mortar pan is equal to 1 Bag of Cement. This number of mortar pan depends upon its area. In the local language, Mortar Pan is also known as Gamala, Tagari, etc.

The first step is to check the number of mortar pans to be required to fill 1 bag of cement. According to my experience 4 Mortar pans needs to fill up with one Bag of Cement.

1 Bag of Cement = 4 Mortar Pan.

Grade of Concrete = M 15 (1:2:4). Where 1=cement, 2 = Fine Aggregate (sand), 4 = Coarse Aggregate. so the proportion can be as follows.

Cement = **One Bag of cement = 1 x 4 Mortar Pan.**

Sand = 2 x 4 Mortar Pan of Sand = **8 Mortar pan of Sand.**

Coarse Aggregate = 4 x 4 Mortar pan of Coarse Aggregate = **16 Mortar Pan of Aggregate.**

In order to prepare M 15 grade of Concrete: 1 Bag of Cement: 8 Mortar Pan of Sand: 16 Mortar Pan of Coarse Aggregate is required.

**The following are the steps to follow for placing the ingredients into the Rotating Drum of the Concrete Mixer.**

- Clean and splash cement slurry on the Rotating Drum of the Concrete Mixture Machine.
- Add the water of about 10-12 liters into Rotating Drum.
- Place 16 Mortar Pan of Coarse Aggregate in mixing Drum followed by 8 mortar pan of coarse sand.
- In order to mix the concrete, water and then Concrete is mix in a Rotating concrete mixer
- After pouring the ingredient, Rotating Drum shall be revolved about 2 to 3 minutes to get uniform mixing.

**Advantage of Using Mortar Pan**

- It is easy to transport the Material from stored area to the Rotating Drum of concrete Mixer.
- It is easy to lift and drop the material into the Drum.

**Disadvantage of Using Mortar Pan**

- The material in the Mortar pan filled at different levels so there is a variation in the proportion of Ingredients.
- However, Due to the carelessness of laborers, there is a chance of missing one or two Mortar pan. It is very difficult to cross-check the ingredients in Rotating Drum.
- Some Times labor adds extra one or two mortar pan into a drum.

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