Specifications

Specifications for RCC Construction | Building Estimating and Costing

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In my earlier articles, I have discussed types of specifications and various purposes for which specifications are to be given. Most of the constructions of various types of buildings are RCC constructions. In this article, we are going to discuss in detail about the specifications that are to be necessarily given for carrying out RCC (reinforced Cement Concrete) constructions.

RCC specifications
RCC specifications

RCC Specifications

  • Shuttering shall be done using seasoned wooden boards of thickness not less than 30mm.
  • Surface contact with concrete shall be free from adhering grout, nails, splits and other defects.
  • All the joints are perfectly closed and lined up.
  • The shuttering and framing is sufficiently braced.
  • Nowadays timber shuttering is replaced by steel plates.
  • All the props of approved sizes are supported on double wedges and when taken out, these wedges are eased and not knocked out.
  • All the framework is removed after 21 days of curing without any shocks or vibrations.
  • All reinforcement bars conform IS specifications and are free from rust, grease oil etc.
  • The steel grills are perfectly as per detailed specifications.
  • The covers to concrete are perfectly maintained as per code.
  • Bars of diameter beyond 25mm diameter are bent when red hot.
  • The materials proportion should be as per the specifications of the concrete.

Number of Cement bags required for a specific cement concrete ratios

  • For cement concrete of ratio 1:1:2(1 cement:1sand/coarse sand:2graded stone aggregate) require 11no bags of 50kg.
  • For cement concrete of ratio 1:1.5:3 require 7.8no bags of 50kg.
  • For cement concrete of ratio 1:2:4 require 6 no bags of 50kg.
  • For cement concrete of ratio 1:3:6 require 4.25no bags of 50kg.
  • For cement concrete of ratio 1:4:8 require 3.2 no bags of 50kg.
  • For cement concrete of ratio 1:5:10 require 2.50 no bags of 50kg.
  • For cement concrete of ratio 1:6:12 require 2.25 no bags of 50kg.

Specifications for Plain Cement Concrete (PCC) | Building Estimation and Costing

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Plain Cement Concrete (PCC) is a construction material generally used as a binding materials and is composed of cement, (commonly Portland Cement) and other cementitious materials such as fly ash and slag cement, aggregate (generally a coarse aggregate made of gravels or crushed rocks such as limestone or granite, plus a fine aggregate such as sand), water, and chemical admixtures.

Cement mixing with sand
Cement mixing with sand

In my earlier articles, I discussed types of specifications, purpose of specifications, RCC specifications, Specifications for Brick masonry in Cement Mortar, Coursed Rubble Masonry Specifications. In this article, we are going to discuss in detail various specifications that are to be given before the initiation of PCC work.

Specifications for Plain Cement Concrete (PCC)

Materials Specifications

Aggregate shall be of invert materials and should be clean, dense, hard, sound, durable, non-absorbent and capable of developing good bond with mortar.

Coarse aggregate shall be of hard broken stone of granite or similar stone, free from dust, dirt and other foreign matters. The stone ballast shall be of 20mm size and smaller. All the coarse material should be retained in a 5mm square mesh and should be well graded such that the voids do not exceed 42%.

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Purpose of Specifications and types of Specifications

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What are Specifications?

Specifications describe the nature and the class of the work, materials to be used in the work, workmanship etc. and is very important for the execution of the work. The cost of a work depends much on the specifications. Specifications should be clear.

Types of Specifications
Types of Specifications

Purpose of giving Specifications

  • The cost of an unit quantity of work is governed by its specifications.
  • Specification of a work is required to describe the quality and quantity of different materials required for a construction work and is one of the essential contract documents.
  • This also specifies the workmanship and the method of doing the work. Thus specification of a work serves as a guide to a supervising staff of a contractor as well as to the owner to execute the work to their satisfaction.
  • A work is carried out according to its specification and the contractor is paid for the same. Any change in specification changes the tendered rate.
  • As the rate of work is based on the specification, a contractor can calculate the rates of various items of works in tender with his procurement rates of materials and labour. Thus tender rate without specification of works is baseless, incomplete and invalid.

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