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Questions and Answers
What is the maximum allowable temperature for concrete during delivery and placement?
What is the maximum allowable temperature for concrete during delivery and placement?
At what temperature should concrete specimens be kept during final curing?
At what temperature should concrete specimens be kept during final curing?
How often should the compression testing machine be calibrated?
How often should the compression testing machine be calibrated?
What percentage of surface area damage on a coated steel reinforcing bar indicates that it should be rejected?
What percentage of surface area damage on a coated steel reinforcing bar indicates that it should be rejected?
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What is the minimum clear distance from anchor bolts or sleeves to the edge of concrete?
What is the minimum clear distance from anchor bolts or sleeves to the edge of concrete?
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What is the maximum distance permitted between manholes for public sewers?
What is the maximum distance permitted between manholes for public sewers?
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What is the minimum distance that public sewers must be separated from potable water lines?
What is the minimum distance that public sewers must be separated from potable water lines?
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What is the minimum pressure rating of valves as specified?
What is the minimum pressure rating of valves as specified?
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What is the minimum inside diameter for storm drain manholes with pipe diameters up to 600 mm?
What is the minimum inside diameter for storm drain manholes with pipe diameters up to 600 mm?
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What is the minimum thickness of sand cover installed on top of direct buried cable or conduit?
What is the minimum thickness of sand cover installed on top of direct buried cable or conduit?
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What percentage of silica fume is required as a replacement by weight of cement?
What percentage of silica fume is required as a replacement by weight of cement?
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What is the minimum size for high strength bolts in bolted connections?
What is the minimum size for high strength bolts in bolted connections?
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What is the minimum thickness of grout between the foundation and base plates?
What is the minimum thickness of grout between the foundation and base plates?
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What is the minimum thickness of a gusset and stiffener plate required?
What is the minimum thickness of a gusset and stiffener plate required?
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How many days should a masonry wall be cured before grout pouring in high lift grouted construction?
How many days should a masonry wall be cured before grout pouring in high lift grouted construction?
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What is the minimum compressive strength of structural concrete at 28 days?
What is the minimum compressive strength of structural concrete at 28 days?
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What is the maximum height that concrete may be allowed to drop freely?
What is the maximum height that concrete may be allowed to drop freely?
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What is the required relative density for free-draining soils to be compacted?
What is the required relative density for free-draining soils to be compacted?
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What is the minimum thickness of paving slabs subject to vehicular traffic?
What is the minimum thickness of paving slabs subject to vehicular traffic?
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Which material is classified as brittle?
Which material is classified as brittle?
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How much natural pozzolan is used in cement?
How much natural pozzolan is used in cement?
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The prime coat should be applied when the atmospheric temperature is what or above?
The prime coat should be applied when the atmospheric temperature is what or above?
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At what rate should the prime coat be applied using a pressure distributor?
At what rate should the prime coat be applied using a pressure distributor?
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What is the minimum temperature for applying the prime coat for MC-70?
What is the minimum temperature for applying the prime coat for MC-70?
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What is the maximum application rate of the tack coat on paved surfaces?
What is the maximum application rate of the tack coat on paved surfaces?
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What is the minimum core thickness measurement required?
What is the minimum core thickness measurement required?
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What is the minimum compressive strength of pre-packaged cement based grout at 28 days?
What is the minimum compressive strength of pre-packaged cement based grout at 28 days?
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What is the minimum time for continuous water curing of grout?
What is the minimum time for continuous water curing of grout?
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What is the maximum working time allowed after mixing grout at a minimum working temperature of 32°C?
What is the maximum working time allowed after mixing grout at a minimum working temperature of 32°C?
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What is the maximum thickness of concrete layers during placement?
What is the maximum thickness of concrete layers during placement?
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What is the minimum required curing time for a masonry wall before grouting?
What is the minimum required curing time for a masonry wall before grouting?
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Which dimension does a gypsum board width typically fall between?
Which dimension does a gypsum board width typically fall between?
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What percentage of compaction is required for base and sub-base of asphalt paving?
What percentage of compaction is required for base and sub-base of asphalt paving?
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What is the minimum clear spacing between parallel bars in a layer?
What is the minimum clear spacing between parallel bars in a layer?
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Which sieve size must 100% of selected fill material pass?
Which sieve size must 100% of selected fill material pass?
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How thick must a cohesive cap layer be when using dune sand as fill material?
How thick must a cohesive cap layer be when using dune sand as fill material?
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What is the minimum time that a plastic sheet should remain on a concrete surface to assess moisture content?
What is the minimum time that a plastic sheet should remain on a concrete surface to assess moisture content?
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Study Notes
Concrete Specifications
- Allowable concrete temperature during delivery and placement should be a maximum of 32°C.
- Concrete specimens should be subjected to final curing with free water maintained on their surfaces at all times at a temperature of 23°C ± 2°C.
- The compression testing machine should be calibrated once in 12 months.
- When the extent of damaged coating exceeds 2% of the surface area of the coated steel reinforcing bar in any 0.3–m (1–ft) length, the coated bar should be rejected.
- Concrete should be discharged from the mixer within 90 minutes or 300 revolutions of the mixer from the time the mixing water was added.
Concrete Cover and Clear Distances
- Minimum concrete cover for permanently exposed concrete structures to earth (including foundations over a sub-slab), weather supporting process equipment foundations should be 75mm.
- Minimum clear distance from anchor bolts or sleeves to the edge of concrete should be 100mm.
- The minimum anchor bolt diameter should be 20mm unless specified by the vendor for small equipment or for the anchorage of small miscellaneous items, e.g., of base or sub-base.
Prime Coat Specifications
- Prime coat should only be applied when the surface to be treated is dry and the atmospheric temperature is 16°C or above.
- Prime coat should be applied uniformly to the surface of the base using a pressure distributor at a rate between 0.65 and 1.75 liters/m2.
- The prime coat should be applied at a temperature between 50°C and 80°C for MC-70.
- The prime coat should be applied at a temperature between 65°C and 105°C for MC-250.
Tack Coat Specifications
- Tack coat should be applied on paved surfaces and vertical surfaces which will be in contact with the asphalt paving by means of a bitumen distributor at a maximum rate of 0.25 liters/m2.
- Tack coats should not be placed during rain, on a moist surface when the air or surface temperature is below 16°C.
- If application of the surface course is delayed by more than 3 days or if dirt, sand, or other impurities have contaminated the tack coat, a new tack coat should be applied after the original one has been swept clean.
Core Measurements and General Requirements
- Measurement of any cores should not be less than 10mm or 15% of the design thickness, whichever is less.
- Core compaction requirements should be equal to or greater than 96% of Marshall density (ASTM D-2726/ASTM D1559) using samples taken at the road site.
- Minimum Compressive Strength of pre-packaged cement-based grout at 28 days should be 5,000 psi.
- Standard temperature of mix should be 23°C ± 2°C when test cubes are cast.
- The compressive strength of the grout should be a minimum of 3,500 psi at 7 days of age.
- Grout should be given a continuous water cure (covered by wet burlap and 0.15 mm polyethylene) for a minimum of 7 days.
- Grout placement should be within 30 minutes at 32°C minimum working time, after mixing.
Public Sewer Specifications
- The maximum distance between manholes for public sewers should be 15m.
- Public sewers that are parallel to potable water lines should be separated from such lines by a minimum distance of 2m and shall be located below the potable water lines.
Underground Piping and Drainage
- Minimum pressure rating of valves should be 12.1 bar.
- For trenches deeper than 1.5 m, RTR pipe should be assembled in the trench.
- The minimum diameter of a storm drain pipe (except building connections) or road crossing culvert should be 300 mm.
- Storm drain manholes should have a minimum inside diameter of 1.0 m for straight run manholes with a pipe diameter size of 600 mm or less.
Cable Trench Specifications
- A minimum of 150 mm of dry sand should be installed from the bottom of the trench to the bottom of the cable or conduit as a cushion.
- A minimum of 300 mm of dry sand cover should be installed on top of the cable or conduit as a cushion.
Gypsum Board Specifications
- Gypsum board width should be 1220 mm to 1370 mm with a tolerance of -2 mm under the specified width.
- Gypsum board corners should be square with a tolerance of ± 2° over the full width of the board.
- Wood supports for lath or gypsum board should not be less than 38 mm in least dimension.
Grout and Bolt Specifications
- The minimum thickness of grout should be 25 mm.
- The minimum thickness of grout between the foundation and base plates should be 25 mm.
- Steel shims and packings should be provided.
- In bolted connections, the minimum size of high-strength bolts that should be used is 20 mm.
- The minimum thickness of gusset and stiffener plates should be 10 mm.
Moisture Content Determination
- The minimum time that a plastic sheet should be in place on a concrete surface to determine its moisture content by the plastic sheet method, ASTM D4263, is 16 hours.
Concrete Slab and Masonry Wall Specifications
- The minimum concrete slab thickness supported on the ground is 100 mm (4").
- A masonry wall should be cured for 7 days prior to grout pouring for high-lift grouted construction.
Fill Material Specifications
- The maximum particle size of fill material should be 1/2 lift thick.
- Fill material classified as "select fill" should contain 0 to 20% particles passing through #200 sieves.
- Fill materials should be placed in lifts or layers not exceeding 200 mm in loose depth.
- Free-draining soils or cohesionless material should be compacted to 70% relative density.
Concrete Strength and Paving Slab Specifications
- The minimum compressive strength of structural concrete at 28 days should be 25 MPa.
- Paving slabs subject to vehicular traffic should have a minimum thickness of 150 mm.
- Control or construction joints for concrete paving should be spaced at a maximum of 6.0 meters in both directions.
Concrete Placement and Grout Strength
- Concrete may be allowed to drop freely at a maximum height of 1 m.
- Cementations non-shrink grout should have a compressive strength of 5,000 psi.
Miscellaneous Steel Specifications
- End-lap for metal panels should not be less than 250 mm.
- A beam with a depth of 8 inches requires 2 rows of bolts.
Brittle Materials
- A material is brittle if, when subjected to stress, it breaks with little elastic deformation and without significant plastic deformation.
- Brittle materials absorb relatively little energy prior to fracture, even those of high strength. Breaking is often accompanied by a snapping sound.
- Examples of brittle materials are: bone, cast iron, ceramic, and concrete.
Concrete Vibrator and Cracking
- We use vibrators to increase the workability and consolidation of concrete.
- Concrete cracking can be caused by dehydration and shrinkage.
Pozzolan Use and Concrete Placement
- Natural pozzolan should be used at 15% of the cement weight.
- Place concrete in layers not exceeding 150 mm in thickness and consolidate.
Base Class Material and Tack Coat Delay
- The laboratory California Bearing Ratio (CBR) per ASTM D1883 or AASHTO T-193 for base class material at 100% compaction DD1557 should conform to minimum 80%.
- Testing should be conducted at a rate of one test every 300 m of base or sub-base.
Gypsum Board Width and Masonry Wall Curing
- Gypsum board width should be 1220 mm to 1370 mm with a tolerance of -2 mm under the specified width.
- A masonry wall should be cured for 7 days prior to grout pouring for high-lift grouted construction.
Lightweight Aggregate and Reinforcement
- Lightweight aggregate should have a dry loose weight of 1600 kg/m3 or less.
- Reinforcement bars are used to resist shear and torsion stresses in a structural member.
- The minimum clear spacing between parallel bars in a layer should be the diameter of the larger bar + 25 mm.
- The minimum bend diameter for No. 16 bar commonly used for stirrups and ties should be 100 mm.
Moisture Content by Plastic Sheet Method
- The minimum time that a plastic sheet should be in place on a concrete surface to determine its moisture content by the plastic sheet method, ASTM D4263, is 16 hours.
Fill Material Compaction and Sand Cushion
- Fill material should be compacted to 95% of the maximum laboratory density.
- Dune sand or clean sand used as fill material requires a cap layer of cohesive material, 150 mm to 300 mm thick.
- The sand cushion used for underground cable shall be a minimum of 150 mm deep.
ACI and Sieve Requirements
- The American Concrete Institute (ACI) is a professional organization for concrete professionals.
- The amount of selected fill material passing #200 sieve should be 100%.
Compaction
- Compaction should begin only after the fill or backfill has been properly placed and the material to be compacted is at the proper moisture content, 95% to 105% of the optimum moisture content per ASTM D1557 or ASTM D698, whichever is applicable.
- Fill or backfill placed beneath footings, grade beams, mats, buildings, and process areas should be compacted to at least 95% of the maximum Modified Proctor density as determined by ASTM D1557.
Damaged Coating and Reinforcing
- When the extent of damaged coating exceeds 2% of the surface area of the coated steel reinforcing bar in any 0.3 m (1 ft) length, the coated bar should be rejected.
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Description
Test your knowledge on concrete specifications including temperature limits, curing conditions, and compression testing machine calibration intervals. Additionally, explore essential guidelines for concrete cover and clear distances related to reinforced structures.
