Specification
Specifications describe the nature and class of work, material to be used and quality of workmanship. It also specifies the order in which the work will be executed and method of execution which should be adopted.
Drawing does not show the details of different items of work, the quantity of material & workmanship that is described in the specification.
Cost of work much depends on the specification, drawing and specification form is an important part of contract documents.
Sources for specification:
(1) Clind requirement
(2) Previous specification of similar contract
(3) Contract drawings
(4) ASTM & BS standards
(5) Code of practice of work
(6) Site investigation
(7) Climatic conditions
Specifications for concrete:
(1) Size of coarse aggregate >=3mm < 20mm
(2) Aggregate must be hard, strong & durable
(3) It must be crushed aggregate
(4) For coarse aggregate elongation (length & width) & flakiness (width & height) index test (value) must be within ASTM limit
(5) Reinforcement must be according to the ASTM standard (15)
(6) Minimum elongation for reinforcement must be 12%
(7) Formwork (shuttering) must also be specified
(8) You also specify that when formwork will be removed ( after 14 days)
(9) For columns you can remove formwork after 24 hours
(10) It must be specify some testing of concrete such as slump test, cube or cylinder test. Slump value is generally taken from70mm to 80mm
(11) Cost of reinforcement must be dealt separately
Specification for Brickwork:
(a) For bricks:
(1) When place the brick in the water tank it should not absorb water more than 15 % of its wt after 24 hours.
(2) Minimum compressive strength of bricks is 2000psi.
(3) Also specify the class of bricks i.e. 1st, 2nd or 3rd class.
(b) For mortar
(1) Cement and sand used in the mortar must be according to there specification.
(2) Ratio of cement & sand must be according to Bill Of Quantity (BOQ)
(3) Mortar must be used within 30 min after addition of water.
(c) For brick laying:
(1) Normally English bond will be used for brickwork until some other bond is specified.
(2) All the courses must be leveled.
(3) Frog should be place upward.
(4) Soaking of bricks is important; bricks should be placed in water tank for 4 hours before use.
(5) All joints must be filled with mortar.
(6) Thickness of joint is 2/8 to 3/8 inch. Joints b/w bricks & columns (RCC) must be secured by using steel ties.
(7) Relative height of two walls must not exceed 5 foot
(8) 4 courses of brick work must give height of one foot
(9) Inter locking of bricks must be there.
(10) Curing must be done for 7 to 10 days.
Specification for plaster:
(1) Removing the mortar from joints of brickwork.
(2) Clean surface of brick work
(3) Ratio must be according to BILL OF QUANTITY (BOQ)
(4) Thickness of plaster is from 1/2 to 3/4 inches.
(5) Surface should be watered before plaster
(6) Plaster shall be cured for 10 days
Specification for road works:
Specification for sub grade:
(1) Clean & grubbing of natural surface & demarcation of center line
(2) If material is taken from barrow points then borrow points must be check by engineer (residential engineer i.e. consultant)
(3) Spreading of material will be done with the help of grader & mixing will be done with Disk harrow (for breaking of lumps)
(4) Work should be done in section
(5) Size distribution should be mention i.e. Sieve #
(6) CBR (California bearing ratio) value is generally not less than 10
(7) Compaction will be done in layers. Thickness of one layer (loose material) shall not be more than 10 inches.
(8) Thickness of compacted layer must be specified “(6 inches)
(9) Every layer will be compacted up to 95% (Proctor value)
(10) The moisture content of soil shall not be more than +2 or -2% of OMC
(11) Sub grade surface should be leveled
(12) Mention the frequency & method of testing.
Specification for sub base:
(1) Soil distribution is mentioned
(2) Wear & tear losses for sub base shall not be more than 50%
(3) CBR value must be lesser than 25
(4) Spreading should be done by grader / pavers
(5) Compaction will be done in layers
(6) Thickness 0f layer will be specified
(7) Each layer will be compacted up to 100 % of dry density of Proctor
(8) M.C should not vary more than 2% of OMC
(9) Segregation will be avoided
(10) Starting from edge of road and moving along longitudinal direction ,we gradually move towards the center for leveling and grading
(11) Overlap is 1/3rd of roller width
Specification for base course:
(1) Size of aggregate must be within the specified limit
(2) Coarse aggregate shall have the %age of wear & tear not mote than 50%
(3) Course aggregate, when subjected to 5 cycles of NaSO4 solution shall not have loss more than 12% (Soundness test for durability)
(4) CBR value should not be less than 80%
(5) Compaction is generally done 100% of proctor or dry density
(6) M.C should not be greater than 2% of OMC
(7) Compaction should be done in layers of specified thickness
(8) Quantity will be measured by theoretical volume as shone in drawings
(9) Specify the Tolerance limits for leveled surface
Specification for Asphalt concrete mix:
(1) Coarse & fine aggregate must have size distribution which lie within the specification limit
Asphalt + Coarse + Fine
(2) Coarse & fine aggregate shall be clean, hard, durable & free from impurities
(3) The %age of wear & tear losses shall not be more 40 %
(4) Lose (coarse) when subjected to 5 cycles of NaSO4 solution should not be greater than 12 %
(5) The portion of aggregate retain on 3/8 inch shall not contain more than 15% by weight of flat & or elongated particles
(6) Penetration test value for asphalt should be within the specified limit
(7) Ductility of Asphalt should not be lesser than 100% (100cm). If it is less than 100% than cracks will produce in the cold weather
(8) Softening point of asphalt should be specified (Normally it melts at about 150c)
(9) Flash point (the temperature at which vapors of asphalt catch fire)of asphalt should not be greater than 240c
(10) Aggregate mix with asphalt spread on prime code according to specified ratio and at specified temperature.
(11) The mixture should be spread at the temperature not less than 140c
Specifications describe the nature and class of work, material to be used and quality of workmanship. It also specifies the order in which the work will be executed and method of execution which should be adopted.
Drawing does not show the details of different items of work, the quantity of material & workmanship that is described in the specification.
Cost of work much depends on the specification, drawing and specification form is an important part of contract documents.
Sources for specification:
(1) Clind requirement
(2) Previous specification of similar contract
(3) Contract drawings
(4) ASTM & BS standards
(5) Code of practice of work
(6) Site investigation
(7) Climatic conditions
Specifications for concrete:
(1) Size of coarse aggregate >=3mm < 20mm
(2) Aggregate must be hard, strong & durable
(3) It must be crushed aggregate
(4) For coarse aggregate elongation (length & width) & flakiness (width & height) index test (value) must be within ASTM limit
(5) Reinforcement must be according to the ASTM standard (15)
(6) Minimum elongation for reinforcement must be 12%
(7) Formwork (shuttering) must also be specified
(8) You also specify that when formwork will be removed ( after 14 days)
(9) For columns you can remove formwork after 24 hours
(10) It must be specify some testing of concrete such as slump test, cube or cylinder test. Slump value is generally taken from70mm to 80mm
(11) Cost of reinforcement must be dealt separately
Specification for Brickwork:
(a) For bricks:
(1) When place the brick in the water tank it should not absorb water more than 15 % of its wt after 24 hours.
(2) Minimum compressive strength of bricks is 2000psi.
(3) Also specify the class of bricks i.e. 1st, 2nd or 3rd class.
(b) For mortar
(1) Cement and sand used in the mortar must be according to there specification.
(2) Ratio of cement & sand must be according to Bill Of Quantity (BOQ)
(3) Mortar must be used within 30 min after addition of water.
(c) For brick laying:
(1) Normally English bond will be used for brickwork until some other bond is specified.
(2) All the courses must be leveled.
(3) Frog should be place upward.
(4) Soaking of bricks is important; bricks should be placed in water tank for 4 hours before use.
(5) All joints must be filled with mortar.
(6) Thickness of joint is 2/8 to 3/8 inch. Joints b/w bricks & columns (RCC) must be secured by using steel ties.
(7) Relative height of two walls must not exceed 5 foot
(8) 4 courses of brick work must give height of one foot
(9) Inter locking of bricks must be there.
(10) Curing must be done for 7 to 10 days.
Specification for plaster:
(1) Removing the mortar from joints of brickwork.
(2) Clean surface of brick work
(3) Ratio must be according to BILL OF QUANTITY (BOQ)
(4) Thickness of plaster is from 1/2 to 3/4 inches.
(5) Surface should be watered before plaster
(6) Plaster shall be cured for 10 days
Specification for road works:
Specification for sub grade:
(1) Clean & grubbing of natural surface & demarcation of center line
(2) If material is taken from barrow points then borrow points must be check by engineer (residential engineer i.e. consultant)
(3) Spreading of material will be done with the help of grader & mixing will be done with Disk harrow (for breaking of lumps)
(4) Work should be done in section
(5) Size distribution should be mention i.e. Sieve #
(6) CBR (California bearing ratio) value is generally not less than 10
(7) Compaction will be done in layers. Thickness of one layer (loose material) shall not be more than 10 inches.
(8) Thickness of compacted layer must be specified “(6 inches)
(9) Every layer will be compacted up to 95% (Proctor value)
(10) The moisture content of soil shall not be more than +2 or -2% of OMC
(11) Sub grade surface should be leveled
(12) Mention the frequency & method of testing.
Specification for sub base:
(1) Soil distribution is mentioned
| Sieve # | 2inch | 1 | 3 / 4 | 4# | 10# | 40# | 20# |
| Distribution | 100% | 75-95 | 40-75 | 30-60 | 20-25 | 15-30 | 2-20 |
(2) Wear & tear losses for sub base shall not be more than 50%
(3) CBR value must be lesser than 25
(4) Spreading should be done by grader / pavers
(5) Compaction will be done in layers
(6) Thickness 0f layer will be specified
(7) Each layer will be compacted up to 100 % of dry density of Proctor
(8) M.C should not vary more than 2% of OMC
(9) Segregation will be avoided
(10) Starting from edge of road and moving along longitudinal direction ,we gradually move towards the center for leveling and grading
(11) Overlap is 1/3rd of roller width
Specification for base course:
(1) Size of aggregate must be within the specified limit
(2) Coarse aggregate shall have the %age of wear & tear not mote than 50%
(3) Course aggregate, when subjected to 5 cycles of NaSO4 solution shall not have loss more than 12% (Soundness test for durability)
(4) CBR value should not be less than 80%
(5) Compaction is generally done 100% of proctor or dry density
(6) M.C should not be greater than 2% of OMC
(7) Compaction should be done in layers of specified thickness
(8) Quantity will be measured by theoretical volume as shone in drawings
(9) Specify the Tolerance limits for leveled surface
Specification for Asphalt concrete mix:
(1) Coarse & fine aggregate must have size distribution which lie within the specification limit
Asphalt + Coarse + Fine
(2) Coarse & fine aggregate shall be clean, hard, durable & free from impurities
(3) The %age of wear & tear losses shall not be more 40 %
(4) Lose (coarse) when subjected to 5 cycles of NaSO4 solution should not be greater than 12 %
(5) The portion of aggregate retain on 3/8 inch shall not contain more than 15% by weight of flat & or elongated particles
(6) Penetration test value for asphalt should be within the specified limit
(7) Ductility of Asphalt should not be lesser than 100% (100cm). If it is less than 100% than cracks will produce in the cold weather
(8) Softening point of asphalt should be specified (Normally it melts at about 150c)
(9) Flash point (the temperature at which vapors of asphalt catch fire)of asphalt should not be greater than 240c
(10) Aggregate mix with asphalt spread on prime code according to specified ratio and at specified temperature.
(11) The mixture should be spread at the temperature not less than 140c
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