1.1 Introduction to Specification
Specification is the specific description of project which describe the nature and class of work, material to be used.
Importance of specification:
- Serves as guide for site engineers.
- Helps to clear misunderstanding and mistake of project.
- For accurate cost estimation and budgeting.
- Help to verify and check strength of material.
- Helps to meet final outcomes of project.
Purpose of specification:
- To specify nature of work.
- To estimate quantity and cost.
- To identify quantity of material.
- To identify material proportion.
- To identify type of workmanship.
Writing specification:
1. Description of material
- Provide clear description of material.
- Includes brand name and model name.
2. Workmanship
- Describe level of workmanship.
3. Tools
- Describe tools and equipment used.
- Provide rental and purchase requirement.
4. Work protection
- Instruction to protect project.
5. Expression
- Use clear and concise language.
6. Clauses of specification
- Include condition to meet work.
- Describe warranties or guarantees of work.
1.2 Specification of RCC
1. Specification material:
a. Cement:
- OPC cement is used i.e. 43 grade & IS 269:2015.
b. Coarse aggregate:
- Should hard dense and durable material like granite, basalt or limestone.
- Maximum size should exceed ¼ th of minimum thickness of member.
c. Fine aggregate:
- Should be clean free from dust, clay and organic material.
- Fineness modulus should not be more than 3.1 and less than 2.3.
d. Water:
- Clean water free from harmful impurities like oil, acid etc.
2. Combination of material:
- Should be M20 grade concrete.
- Mix proportion of cement, fine aggregate, coarse aggregate and water should be 1:1.5:3: 0.5 by weight.
- Concrete should mix mechanically using batch mixture.
3. Steel Reinforcement using IS code:
a. According IS 1786:2008, steel bar should have minimum yield strength of 415 N/mm2.
b. Steel bar should be free from rust, oil and any deleterious material.
c. As per IS 456:2000, cover should be measured from outer surface of reinforcement to surface of concrete.
d. Reinforcement should be placed as per drawing.
1.3 Specification of brick masonry
1. Specification of material:
a. Brick:
- Use 1st class brick.
- Should be in uniform shape and size.
b. Mortar:
- Should be good quality and free from lumps.
- Ratio should be (C:S:W = 1:4:0.5).
2. Combination of material:
a. Brick masonry:
- Should be laid in English bond.
b. Reinforced brick masonry:
- Should be laid in Flemish bond.
3. Steel reinforced using IS code:
- As per IS 432:1982
- Minimum diameter of steel bar = 6 mm
- Minimum cover of steel reinforcement = 15 mm
- Placed in alternative course.
- Spacing should not be more than 300 mm in horizontal and 450 mm in vertical direction.
1.4 Specification of PCC
1. Material specification:
a. Cement:
- As per IS 8112, use OPC of grade 43.
b. Coarse aggregate:
- As per IS 383, nominal size 20 mm.
c. Fine aggregate:
- Should be free from dust and organic matter.
2. Combination of material:
- W/C ratio = 0.5
- (Cement: Sand: Aggregate) = (1:1.5: 3)
3. Steel reinforcement:
- As per IS 1786
- Grade of steel should be Fe500 or Fe415
- Diameter not more than 16 mm.
- Spacing not more than 150 mm and not less than 75 mm.
- Should be free from rust and impurities.
References:
- Dutta, B.N. – Estimating and Costing in Civil Engineering, UBS Publishers, New Delhi.
- CPWD (Central Public Works Department), India – Standard Schedule of Rates and Analysis of Rates.
- IS 1200 – Indian Standard for Method of Measurement of Building and Civil Engineering Works, Bureau of Indian Standards (BIS).
- Punmia, B.C. – Estimating and Costing, Laxmi Publications.
- Building Estimation and Costing Notes – Department of Civil Engineering, Pokhara University.
- MoUD Nepal – Standard Norms and Guidelines for Public Infrastructure Development Projects.