PCC BELOW FOOTING

Building Construction Ideas - Topic 5

( Welcome to the FIFTH article. For more, please visit the links at bottom of the page. )

After completing Boulder Soling of required depth in footing, PCC Should be done over it.

PCC stand for Plain Cement Concrete. It is called plain because there is no reinforcement involved in it. The height of the PCC in foundation ranges from 10-15 cm and it is done of exact size (L*B) of footing. 

Fig 1: PCC in foundation ( Rebar as column centre) 

Here are the process of doing PCC in foundation:

Preparation of Surface

1) Check the line and level of the boulder soling in all the footings ( check level by the help of auto level) . If there is +- 2 cm in level difference, you can proceed for PCC.

2) Give a required level in all the foundation with the help of auto level or give it in one foundation and transfer the level in other foundation with the help of level pipe.

3) Prepare the formwork of required size and place it on the boulder soling. Formwork is not mandatory for the PCC but it is advised for good finish. Boulder soling of extra 5cm on all faces is advised for perfect placement of formwork.

4) Once the line and level is fixed, the surface should be cleaned by water. The mud attached with stones should be washed completely for the placement of concrete. 

Concreting

1) Generally, the ratio of concrete used for PCC is 1:3:6 ( M10).

2) 1 bag of cement is used for preparing 1 batch concrete and aggregate shall be measured by volume in a gauge box of correct and approved size based on the weight of the material or by other approved accurate means i.e. 3 box of sand and 6 box of aggregate.

Fig 2: Wheelbarrow

3) Water Cement Ratio for M10 concrete is taken approximately 0.70 i.e. 34-36 Ltr of water is required for 1 batch of concrete.

4) The cement and aggregates shall be thoroughly mixed together until the mix is uniform in the specified proportions by volume in a batch type mechanical mixer. 

5) Concrete shall be transported with the help of wheelbarrow (gada).

Placement of Concrete

1) At the time of placing the fresh concrete, it shall not have a temperature of more than 30°C and not less than 20°C for large footings. No concrete shall be placed in open, while it rains.

Fig 3: Chutes

2) The concrete shall be deposited as nearly as possible in its final position without re-handling or segregation.

3) Concrete shall not be dropped through a free height greater than 1.50 m.Where the work requires the concrete to be deposited from a height exceeding 1.50 m, trunking and chutes to the Engineer's approval shall be used to prevent segregation of materials.

4) Concrete should be properly laid, levelled and finished in required line and level. The surface finish of PCC shall be roughly smooth for proper bonding with footing concrete (RCC).

Fig 4: Finished Surface of PCC

Thanks for reading this article. For the complete idea of building construction please see other articles of this series.. )

HERE