CONSTRUCTION

Introduction:

As the ultimate owner of the property you are building, you have to ensure that you are getting a durable building; the average lifespan of a building being around 100 years.

The constructed house must have the following characteristics-

  • Be within specified time and budget.

  • Aesthetic and pleasing to the eye.

  • Comfortable to live in.

  • Durable.

You are advised to engage experienced professionals such as engineers, contractors and the field level technicians for executing your project.

What is the Remedy? : Engaging an independent consultant is the ideal system to ensure quality construction but it means additional costs and one may hesitate to engage a consultant. In that case, what is the best that can be done?

Following are some tips-

  • Understand and discuss with trusted aides every aspect of construction.

  • Before awarding the contract, specify materials or ask the contractor to supply the brands/ quality of material he will use. Cross check with an independent civil consultant.

  • Try and use only standardized material (say, BIS) and well-known brands.

  • Use independent testing agencies to examine important specimens like a compressive strength of concrete.

  • Ensure the contractor strictly adheres to quality and uses a material as specified by you. Also, ensure proportions of materials are as mutually agreed.

  • Inspect everything yourself and ensure that the contractor is supervising too.

Concept of Durability:

With respect to concrete, quality assurance means inspection starting with proper selection, proportioning, mixing, handling, placing and curing of materials. Concrete structures may face problems such as structural failures, cracking, rusting of bars, sulfate / chloride attack, surface cracks, segregation, undulations, surface problems like lime leaching etc.

These problems usually manifest later on, hence for civil structures, quality assurance is more vital than the quality control. Prevent these problems by carefully choosing the materials, men and methods and ensuring output quality as per original plan.

Following are some of the means of assuring quality and preventing problems:

  • Do the soil test at the site first and then go in for the design.

  • Check the building contractor’s credentials and track record.

  • Award contract in writing, clearly stating the rates, specifications and usage of standardized and high-quality materials, inspection procedures and quality control.

  • Purchase materials only from reputed brands, preferably with ISO-9001 certification.

  • Consider using blended cement and/or ready mix concrete instead of the conventional site mix concrete wherever possible to ensure quality and right mix for the construction.

  • Regularly supervise the contractor for material storage conditions and ensure that the reinforcement bars are not corroded.

  • Ask for the test results of cube specimens and note for any significant variations.

Four Legs Concept:

Any construction activity can be compared to a table. Just as a table has four legs, a construction project has four important components.

Following are the key components of construction:

  • Structural Design

  • Mix Design

  • Materials

  • Workmanship

Structural Design: Right structural design means that the members of the structure such as concrete columns, slabs, foundation, walls etc are designed to withstand the forces that will come on them. The structural engineer analyzes forces affecting structural members in trusses, frames, beams, and columns and calculates the resulting stresses and designs their sizes accordingly.

Mix Design:

Mix design refers to a design of concrete mix that involves the specification of the proportion of materials like cement, aggregates, sand, water and admixtures that will give a specific grade and workability.

In conventional site mix concrete, the mixing is done manually and on the volumetric basis. It is advisable to use ready mix concrete which is made in a batching under controlled conditions and undergoes tight quality control

Materials:

The materials used for construction forms the third leg of construction. As far as possible, use only standardized material (materials having an ISI Code) and reputed brands.

Cement:

  • Cement is the binder that holds concrete and mortars together. For construction purposes, blended cements are the best.

  • The Color of the cement does not have any effect on the quality of cement.

  • Good brands of cement may cost 2 to 5% extra but offer quality, consistency and reliability as well as 10 to 20% greater strength characteristics.

  • Cement must be added to the concrete and mortar in a precise, consistent manner.

  • Cement must be stored dry, say by covering with tarpaulin, until final mixing into a construction material.

Sand:

Proper selection of sand is critical in the durability and performance of your concrete mixture. It should be river sand, clear, angular and hard. It must be free from clay, mica and soft, flaky material. It should be a mix of fine, medium and coarse sand, free from contaminants like sea salt. Moisture (water) content must be consistent (which should not exceed 7%).

Aggregates (Stone Chips):

  • They are major ingredients of concrete, giving it strength and solidity. The quality of concrete depends on the characteristics of aggregates used.

  • Stone chips should be angular or round, not flat or flaky. They should not contain marks or layers of any other colour.

  • They should be free from mud and other impurities, which are harmful to concreting. It is advisable to wash the stone chips before mixing, to make it free from dust, dirt and mud.

  • They should be well-graded. Which means these should contain sizes from 5mm to 20mm in proper proportion, so that voids are minimal.

Reinforcing steel:

Reinforcing steel contributes to the tensile strength of concrete. It is wise to buy good brands like SAIL (names are marked on the steel).

  • Ensure that size and type of steel reinforcement is exactly as per the engineering design specifications.

  • Steel bars/rods should be reasonably clean and free of rust.

  • Bars that cannot be easily bent manually or mechanically should be rejected.

  • Choose optimum length bars to reduce wastage in cutting.

  • Shorter bars or welded lengths of bars must not be accepted.

Water:

Use only potable water in quality concrete production.

Bricks:

  • They should be uniform in texture and colour.

  • When broken, they must not leave lumps and grit.

  • Ensure that bricks are not made from saline clay. Look for proper and uniform burning.

Workmanship:

The Workmanship is the fourth pillar of construction. The field level technicians like mason, plumbers, bar benders etc are very important components of good construction.

Some examples of poor workmanship are:

  • Not curing the concrete structures properly.

  • Inability to select good material.

  • Not caring for proper storage of materials.

  • Not properly vibrating the concrete.

  • Adding water and diluting the concrete mix after it is taken out of the mixture.

  • Walking on the reinforcement bars / form work before placing the concrete.

  • Not soaking the brick in the water properly before laying.

Insist on strict supervision by the contractor at the contracting stage itself.

© 2020 by South Land Developers.

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