90+ Thumb Rules For Civil Engineering And Quantity Surveyors | Essential Formulas

The document titled 90+ Thumb Rules For Civil Engineering And Quantity Surveyors | Essential Formulas provides a comprehensive collection of essential guidelines for professionals in the field. With a formal tone, this document serves as a valuable resource for civil engineers and quantity surveyors seeking fundamental principles and formulas. Accessing this wealth of knowledge can greatly benefit individuals involved in these disciplines, aiding in the successful execution of projects and accurate quantity estimations.

Civil engineers, site engineers, or supervisors must be familiar with Thumb Rules for Civil Engineering. These rules assist in making quick and efficient decisions on-site. They help estimate materials, dimensions, and construction parameters with simple mathematical formulas. However, these rules provide approximations and not exact results.

Thumb Rules for Concrete Work

• 28 days strength is the characteristic strength of concrete – Determines the concrete strength after 28 days of curing.
• One-fourth of the concrete section should have steel reinforcement – Estimates steel reinforcement in slabs and foundations.
• Excavation depth should be 1.5 times the foundation width – Ensures structural stability.
• The water-cement ratio should be 0.5. This helps maintain durability and strength.
• A single layer of vibrator for every 12 feet – Ensures proper compaction and reduces air bubbles.
• A slump test should be performed before pouring concrete – Checks the consistency of the concrete mix.
• Volume of concrete required = 0.038 m³ /sq. ft. – Used for quick calculations of concrete volume.

Thumb Rules for Slab

• Minimum slab thickness – 125mm.
• Minimum diameter of bars – 8mm.
• Fe 500 Steel should be used in RCC slabs.
• Clear cover for reinforcement – 15-20mm.
• Maximum bar diameter – 1/8th of slab thickness.
• Steel required in RCC slab – 1% of total concrete volume.
• M15 grade concrete or higher should be used.
• Reinforcement spacing – Not less than 150mm c/c.

Thumb Rules for Beam

• Steel required in RCC beam – 2% of total concrete volume.
• Minimum clear cover – 40mm.
• Minimum reinforcement – 4 bars: 2 bars of 12mm at the top and 2 bars of 10mm at the bottom.
• M20 grade concrete should be used in RCC beam construction.
• Spacing of reinforcement bars – Not less than 150mm c/c.

Thumb Rules for Column

• Steel reinforcement spacing – Not more than 300mm.
• Minimum clear cover – 40mm (25mm for columns < 200mm).
• M20 grade concrete is recommended for columns.
• Fe 500 steel is recommended for reinforcement.
• Minimum bar diameter – 12mm, with at least 4 bars per column.
• Maximum reinforcement bar diameter – 50mm.
• Overlapping distance – 24 times the smallest bar diameter.
• Maximum stirrup spacing – 16D, B, or 300mm (whichever is lesser).
• Steel required in the column – 2.5% of total concrete volume.
• Minimum steel requirement in column – 0.8% of gross concrete area.
• Maximum steel requirement in column – 6% of gross concrete area.
• Minimum column size – 9” x 9”.
• G+1 structures – Use 9” x 12” (225mm x 300mm) RCC columns.
• Maximum column spacing – Not more than 4 meters for a 9” x 9” column.

Thumb Rules for Foundation

• Steel required in RCC footing – 0.8% of total concrete volume.
• Clear cover for footing reinforcement – 50mm.
• Minimum bar diameter – 10mm.
• M20 grade concrete or higher should be used.
• Foundation dimensions – Length, width, and depth should not be less than 1 meter.
• Minimum footing thickness – 40cm.
• Pile foundation is required if the soil bearing capacity is < 24 kN/m³.

Thumb Rules for Building Estimation

• Steel required for residential buildings – 4.5 – 4.75 kg/sq. ft.
• Steel required for commercial buildings – 5.0 – 5.5 kg/sq. ft.
• BN Datta recommendations for accurate results.

Steel Quantity in Structural Members:

• Slab – 1% of concrete volume.
• Beam – 2% of concrete volume.
• Column – 2.5% of concrete volume.
• Footings – 0.8% of concrete volume.

Thumb Rule for Shuttering Work

• Shuttering costs – 15-18% of the total construction cost.
• Shuttering quantity – 6 times concrete quantity or 2.4 times plinth area.
• Example: For 0.5m³ of concrete, shuttering area = 0.5 x 6 = 3m².

Components of Shuttering:

• Ply Sheets – Required quantity = 0.22 x shuttering area.
• Battens Quantity – 19.82 x No. of Ply Sheets.
• Nails & Binding Wire – 75g per 1m² of shuttering.
• Shuttering Oil – 1 liter for every 15m².

Thumb Rules for Brickwork

Brickwork Cement Requirement:

Thumb Rules for Cement Masonry Quantity

Masonry Mix Ratios & Cement Consumption:

Thumb Rule for Plastering Work

Cement Setting Time

• Initial Setting Time – 30 minutes (measured with Vicat Apparatus).
• Final Setting Time – Depends on cement type and grade.

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