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Things Site Engineers Must Know About Reinforcement and Steel Bars

As Per Indian Guidelines Only.

Clear cover to main reinforcement in
Footings : 50 mm
Raft foundation Top : 50 mm
Raft foundation Bottom/ sides : 75 mm
Strap Beam : 50 mm
Grade Slab : 20 mm
Column : 40 mm (d>12mm) 25 mm (d= 12mm)
Shear Wall : 25 mm
Beams : 25 mm
Slabs : 15 mm or not less than diameter of the bar.
Flat Slab : 20 mm
Staircase : 15 mm
Retaining Wall on Earth : 20/ 25 mm
Water retaining structures : 20 / 30 mm
Sunshade (Chajja) : 25 mm

Hook for stirrups is 9D for one side

No. of stirrups = (clear span/Spanning) + 1

For Cantilever anchorage length for main steel is 69D

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“L” for column main rod in footing is minimum of 300mm

Chairs of minimum 12 mm diameter bars should be used.

Minimum diameter of dowel bars should be 12 mm

Lap slices should not be used for bar larger than 36 mm.

In steel reinforcement binding wire required is 8 kg per MT.

Lapping is not allowed for the bars having diameters more than 36 mm.

Minimum number of bars for a square column are 4 and for circular column are 6.

Longitudinal reinforcement should not be less than 0.8% and more than 6% of gross C/S.

Weight of rod per meter length = d2/162 where d is the diameter in mm

All reinforcement shall be free from mill scales, loose rust & coats of paints, oil or any other substances.

Main bars in the slabs shall not be less than 8 mm (HYSD) or 10 mm (Plain bars) and the distributors not less than 8 mm and not more than 1/8 of slab thickness.

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In case of spacing of bars
Provide the diameter of the bar, if the diameter of the bar are equal.
Provide the diameter of the larger bar, if the diameter are unequal.
5mm more than the nominal maximum size of the coarse aggregate.

Things Site Engineers Must Know

Check out the Unit Weights and Conversion which will be required on construction site here

We at engineeringcivil.com are thankful to Er Vikrant for submitting this construction site check list which is of great use to all civil engineers.

Things Site Engineers Must Know

Minimum thickness of slab is 125 mm.

Water absorption should not be more than 15 %.

Dimension tolerance for cubes + – 2 mm.

Compressive strength of Bricks is 3.5 N /mm2

Maximum Free fall of concrete allowed is 1.50 m.

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In soil filling as per IS code for every 100 sqm 3 sample for core cutting test should be taken.

Electrical conduits shall not run in column

Earth work excavation for basement above 3 m should be stepped form

Any back filling shall be compacted 95% of dry density at the optimum moisture content and in layers not more than 200mm for filling above structure and 300 mm for no structure

F soling is specified the soling stones shall be laid at 45° to 60° inclination (and not vertical) with interstices filled with sand or moorum.

A set of cube tests shall be carried out for each 30 cum of concrete / each levels of casting / each batch of cement.

Water cement ratio for different grades of concrete shall not exceed 0.45 for M20 and above and 0.50 For M10 / M15 contractor

For concrete grades M20 and above approved admixture shall be used as per mix design requirements.

Cement shall be stored in dry places on a raised platform about 200mm above floor level and 300mm away from walls. Bags to be stacked not more than 10 bags high in such a manner that it is adequately protected from moisture and contamination.

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Samples from fresh concrete shall be taken and at least a set of 6 cubes of 150mm shall be prepared and
cured. 3 Cubes each at 7 days and 28 days shall be tested for compressive strength. The test results
should be submitted to engineer for approval. If results are unsatisfactory necessary action/rectification/remedial measures has to be exercised.

Water used for both mixing and curing shall be clean and free from injurious amounts of oils, acids, alkalies, salts, sugar and organic materials or other substances that may be deleterious to concrete or steel. The ph shall be generally between 6 and 8.

Cement shall be tested for its setting.
1. The initial setting time shall not be less than 30 minutes.
2. The final setting time shall not be more than 10 hours.

Slump IS 456
Lightly reinforced 25 – 75 mm
Heavily reinforced 75 – 100 mm
Trench fill (insitu & Tremie) 100 – 150 mm (For Tremie no need of vibrator)

Curing Days Required
Super Sulphate cement : 7 days
Ordinary Portland cement OPC : 10 days
Minerals and Admixture added cement : 14 days

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Cube Samples
1 – 5 M3 : 1 No.
6 – 15 M3 : 2 No’s
16 – 30 M3 : 3 No’s
31 – 50 M3 : 4 No’s
Above 50 M3 : 4 + 1 No of addition sample for each 50 M3.

Things Site Engineers Must Know About Reinforcement and Steel Bars

Check out the Unit Weights and Conversion which will be required on construction site here

We at engineeringcivil.com are thankful to Er Vikrant for submitting this construction site check list which is of great use to all civil engineers.

What are the Tolerance Limits on Construction Site?

Accuracy of measuring equipment in batching plant.
Cement : + – 2%
Aggregate : + – 3%
Admixture : + – 3%
Water : + – 3%
Mixing time : 2 minutes for one mixing. (Mixing which is being done on site)

Tolerance in Form work
In C/S for columns & Beams deviation is = + 12mm more (or) – 6mm less in size
In footing plan = + 50 mm more (or) – 12 mm less size
In depth = + – 0.05 D (specified thickness).

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Tolerance in Reinforcement
For effective depth D < = 200mm = +- 10mm For effective depth D > 200mm = +- 15mm
For Cover to reinforcement = + 10mm
Maximum freefall of concrete = 1.50 m height.

Tolerance on diameter in length
0-25mm = +- 0.5 %
25-35mm = +- 0.6 %
35-50mm = +- 0.8 %

Tolerance on weight per metre
0-10mm = +- 7%
10-16mm = +- 5%
16 and above = +- 3%

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Tolerance for cutting Length
A) When the specified length is not given = + 75mm (or) – 25 mm
B) When the minimum length is specified = + 50 mm (or) – 0 mm

We are thankful to Er. Vikrant for submitting this to us.

Various Types Of Cranes

A crane is a tower or derrick that is equipped with cables and pulleys that are used to lift and lower material. They are commonly used in the construction industry and in the manufacturing of heavy equipment. Cranes for construction are normally temporary
structures, either fixed to the ground or mounted on a purpose built vehicle.

They can either be controlled from an operator in a cab that travels along with the crane, by a push button pendant control station, or by radio type controls. The crane operator is ultimately responsible for the safety of the crews and the crane.

Mobile Cranes

The most basic type of crane consists of a steel truss or telescopic boom mounted on a mobile platform, which could be a rail, wheeled, or even on a cat truck. The boom is hinged at the bottom and can be either raised or lowered by cables or hydraulic cylinders.

Mobile_Cranes

Telescopic Crane
This type of crane offers a boom that consists of a number of tubes fitted one inside of the other. A hydraulic mechanism extends or retracts the tubes to increase or decrease the length of the boom.

Telescopic_Mobile_Crane

Tower Crane
The tower crane is a modern form of a balance crane. When fixed to the ground, tower cranes will often give the best combination of height and lifting capacity and are also used when constructing tall buildings.

Tower_crane_picture

Truck Mounted Crane
Cranes mounted on a rubber tire truck will provide great mobility. Outriggers that extend vertically or horizontally are used to level and stabilize the crane during hoisting.

Truck_Mounted_Crane_Knuckle_Boom_picture

Rough Terrain Crane
A crane that is mounted on an undercarriage with four rubber tires, designed for operations off road. The outriggers extend vertically and horizontally to level and stabilize the crane when hoisting. These types of cranes are single engine machines where the same engine is used for powering the undercarriage as it is for powering the crane. In these types of cranes, the engine is normally mounted in the undercarriage rather than
in the upper portion.

Rough_terrain_crane_picture

Loader Crane
A loader crane is a hydraulically powered articulated arm fitted to a trailer, used to load equipment onto a trailer. The numerous sections can be folded into a small space when the crane isn’t in use.

Loader_Crane_picture

Overhead Crane
Also refered to as a suspended crane, this type is normally used in a factory, with some of them being able to lift very heavy loads. The hoist is set on a trolley which will move in one direction along one or two beams, which move at angles to that direction along elevated or ground level tracks, often mounted along the side of an assembly area.

Overhead_Crane_picture

In the excavation world, cranes are used to move equipment or machinery. Cranes can quickly and easily move machinery into trenches or down steep hills, or even pipe. There are many types of cranes available, serving everything from excavation to road work.

Cranes are also beneficial to building bridges or construction. For many years, cranes have proven to be an asset to the industry of construction and excavating. Crane operators make really good money, no matter what type of crane they are operating.

This article was submitted by Er. Vikrant

Compact Excavator

The compact hydraulic excavator can be a tracked or wheeled vehicle with an approximate operating weight of 13,300 pounds.Normally, it includes a standard backfill blade and features an independent boom swing. The compact hydraulic excavator is also known as a mini excavator.

A compact hydraulic excavator is different from other types of heavy machinery in the sense that all movement and functions of the machine are accomplished through the transfer of hydraulic fluid.The work group and blade are activated by hydraulic fluid acting upon hydraulic cylinders.The rotation and travel functions are also activated by hydraulic fluid powering hydraulic motors.

Most types of compact hydraulic excavators have three assemblies – house, undercarriage, and the work group.

Compact_Excavator_image

House
The house structure contains the compartment for the operator, engine compartment, hydraulic pump and also the distribution components. The house structure is attached to the top of the undercarriage via swing bearing. Along with the work group, them house is able to rotate upon the undercarriage without limit due to a hydraulic distribution valve that supplies oil to the undercarriage components.

Undercarriage
The undercarriage of compact excavators consists of rubber or steel tracks, drive sprockets, rollers,idlers, and associated components and structures.The undercarriage is also home to the house structure and the work group.

Work group
The work group consists of the boom, dipper or arm, and attachment. It is connected to the front of the house structure via a swinging frame that allows the work group to be hydraulically pivoted left or right in order to achieve offset digging for trenching parallel with the tracks.

Independent boom swing
The purpose of the boom swing is for offset digging around obstacles or along foundations,
walls, and forms. Another use is for cycling in areas that are too narrow for cab rotation. Another major advantage of the compact excavator is the independent boom swing.

Backfill blade
The backfill blade on compact excavators are used for grading, leveling, backfilling, trenching, and general dozer work. The blade can also be used to increase the dumping height and digging depth depending on it’s position in relation to the workgroup.

The most common place you’ll find compact excavators is in residential dwellings. When digging phone lines or other things, these pieces of equipment are very common for getting between houses. Due to their small size, they can fit almost anywhere.Over the years, the capabilities for compact excavators have expanded far beyond the tasks of excavation. With hydraulic powered attachments such as breakers, clamps, compactors and augers, the compact excavator is used with many other applications and serves as an effective attachment tool as well. Serving many purposes, the compact excavator is a great addition to any job that requires the use of machinery.

This article is submitted by – Er. Vikrant

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