Vertiality Checks for column formwork

Formwork is a temporary structural system, which provides the casing and supporting to the wet concrete to get the required shape. It should be stabled with the weight of the concrete, reinforcement, and other live loads during the construction and compacting of concreting.

After constructing the formwork for columns it is necessary to check for correct vertiality   before concreting.

For small scale formworks a simple center plumb can be used to check the vertiality.

vertiality check using a center plumb

vertiality check using a center plumb

Two center plumbs and a steel tape is required for this process. Center plumbs were hanged at two positions in the same plane with a known distance of 150 mm measured from the inner surface of the plywood sheet(or steel formwork). The distance from the plywood sheet to the thread of the center plumb is measured  using the steel tape at both top and the bottom of the form work.

calculations for a plywood formwork is as follows..

Offset distance from the column edge                                     =          150 mm

Plywood thickness                                                                              =          12 mm

Distance between the plywood and the plumb                      =          150-12

=        138 mm

If the verticality of the column is accurate the distance between the plywood and the center plumb thread should be 138 mm everywhere.Jack supports or locking systems of the formwork can be adjusted to obtain the correct vertiality in case of a mismatch.

A Thedolite  and a steel tape can  also be  used to obtain better accracy. This method is perticulary usefull when checking a large number of  formworks along a one grid line.

The process is described below.

Vertiality check using a digital Thedolite

Vertiality check using a digital Thedolite

Set up the digital theodolite centering a peg which was set up with a 500 mm offset to the column grid. Take  the direction by focusing the telescope to a distant peg which was set up with a 90 º angle to column grid line. After theodolite was set up accurately turn on the laser beam and focused it to the steel tape which is held to the formwork. Take the reading of the steel tape through the telescope. Take the readings of two positions at the same level on both top and bottom levels of the formwork. By taking two readings at the same level any curvature on the surface can be identified.

sample calculation

Offset distance from the column grid            =          500mm

Plywood thickness                                           =         12mm

Size of the column                                           =         300mm

Accurate reading through the telescope         =         500-150-12

=        338mm

Accordingly for correct verticality 338mm reading should be read through the telescope.

Acro jacks and locks can be adjusted to obtain the correct verticality

HELLO.127.th

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Autodesk-Architectural Desktop As a Power Tool in Project Management reports !!

Autodesk-Architectural Desktop is widely used as a 3D modeling software in the construction industry, mainly for architectural purposes..

It is a user friendly software rich with a wide variety of modeling techniques that enables the user to model 3D structures complete with all the details..

This software can also be used as a project management tool in terms of presenting monthly or weekly progress of  the project in detail …

A user can create a model according to the structural drawings  and then  update it with the construction progress.. Different colors and layers  can be utilized to show different elements such as walls, columns ,bases etc. By switching these layers on and off  an individual assessment on the progress of the certain element can be easily obtained. Pictures of the construction process obtained in this manner are of great value in management reports such as monthly progress reports. These 3D pictures give a clear idea about the progress of the construction and enables an overall picture of the process than just looking at  a table ..

Following pictures are some example of the process…

Monthly progress: December

Site situation as at 1st December

Site situation as at 1st December

Site progress as at 31st December

New Picture

Earth Fill    New Picture (1) Column concrete   New Picture (4)

Tie Beam   New Picture (2) Base Concrete New Picture (5)

Random Rubble Masonry  New Picture (3)

New Picture (6)

Base Concreting   45%  completed

Column Concreting

(i)Up to DPC Level 45%  completed

(ii)Above DPC Level 35% completed

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Tie Beams 45% completed

Tie Beams 45% completed

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Random Rubble Masonry

Random Rubble Masonry

56% completed

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Earth fill      34% completed

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Earth fill      34% completed

Slab formwork in pics !!

slab formwork is the  temporary mould in to which concrete is poured during slab concreting.It is a time consuming work  that needs the touch of skilled labors. followings are just a description of the process in pics… Construction-08-june

columns concreted up to the beam bottom level

columns concreted up to the beam bottom level

Slab formwork can be started  after concreting the columns up to the bottom level of  slab beams.

arrangement of beam bottoms and beam reinforcement

arrangement of beam bottoms and beam reinforcement

Formwork for slab beams are then erected between the columns..

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slab formwork arrangement

cross section drawing of a slab formwork

New Picture (1)slab formwork arrangement

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plywood sheet arrangement of slab formwork

these plywood sheets are usually given a coating of form oil

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plywood sheet arrangement of slab formwork

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GI pipes,Acro(T) jack and 2"x4" timber arrangement that supports the formwork...

details of this arrangement are given in the above Auto Cad drawing

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Reinforcement arrangement of the slab formwork...

reinforcement is provided with cover block to protect the steel from moisture and to obtain a certain degree of fire resistance depending on the structure…

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concrete cover block used in this slab form work...

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Tests on concrete compressive strength !!

1)    Cube Test

cube test

Compacting of Concrete Cubes

This is the conventional method of testing the compressive strength of concrete. This can be described as a “destructive” method of testing as casted concrete cubes are crushed to determine the compressive strength.

concrete

crushing of cubes

In this testing procedure concrete cubes are casted in a standard way such that they represent the batches of concrete used for concreting. The cubes are of the size 150x150x150mm and each cube is casted in three layers with specified compaction to each layer. Cubes are properly cured and crushed at the ages of 7, 28 etc. Three cubes are crushed at a time and their mean crushing strength is taken as the compressive strength of concrete.

2)    Impact Hammer Test


impact hammer test

Impact Hammer Test

This is a test specially designed for non-destructive testing of concrete structures. Using this test large areas can be tested for compressive strength consuming less time and money. Possibility of determination of concrete quality between different sections is also an advantage of this test.

The testing is done by pressing a impact plunger against a solid surface of concrete. The maximum height of rebound is recorded and a rebound number is obtained according to the scale of Impact Hammer. This rebound number can then be converted in to compressive strength via conversion tables provided with the equipment. These conversion values vary with the angle of testing and therefore angular corrections should be applied when necessary.

3)    Ultrasonic Test.


ultrasonic test

Ultrasoinc Test

Ultrasonic test for concrete is a field test for quality control and inspection of concrete structures. It uses measurement of the speed of ultrasonic pulses through the concrete to correlate concrete strength to standard strength. Using this test we can identify non-homogeneous conditions in the structure such as honeycombs, voids, cracks and frozen concrete.

First the instrument is calibrated using a standard calibration bar and the receiving and the transmitting ends are coated with a thin uniform grease layer. The concrete surface is cleaned well to make it dust free and uniformly distributed grease layer is applied on the concrete surface as well. The transmitting and receiving ends of the apparatus is then placed on marked locations of the structure and the machine is turned on to get the reading. The test is repeated after switching the positions of the transmitting and receiving ends. Then obtained readings are compared with the standard values to arrive at a conclusion about the concrete quality.

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Russian Civil Engineering and Construction Hardware !!

When you are working at a construction site what will you do if a big military camouflaged tank appears from across a corner. Just don’t panic as you’ll find it is   equipped with a hoe instead of the gun.  🙂

Some companies in Russia earn their living by buying cheap old Russian army vehicles and converting them to civil engineering and construction hardware that then is being used at the various construction sites.

Enjoy…

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Download Surfer 8 !!

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Surfer is a contouring and 3D surface mapping program that runs under Microsoft Windows. It quickly and easily converts your data into outstanding contour, surface, wireframe, vector, image, shaded relief, and post maps.It quickly and easily converts your data into outstanding contour, surface, wireframe, vector, image, shaded relief, and post maps. Virtually all aspects of your maps can be customized to produce exactly the presentation you want.Virtually all aspects of your maps can be customized to produce exactly the presentation you want. Producing publication quality maps has never been quicker or easierProducing publication quality maps has never been quicker or easier.

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Basic Setting Out of a Building

This is the process of obtaining the positions of the structural parts of a building in the geometrical construction. The positions of the structural parts of a building can be obtained by detailed structural drawings. These data has to be transferred to the field to start the geometrical construction with sufficient accuracy; enabling independent checks for readily detecting of any errors.
setting out ....from drawing's to life

setting out ....from drawing's to reality

The first step in building setting out is to identify a base line according to the site layout plan. We can establish the base line considering the permanent structures and the relevant distances to structural parts from them as given in the drawings.

Step 1: Obtaining of a Base Line

Step 1: Obtaining of a Base Line

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Step 1: Obtaining of a Base Line

Setting out is done based on the principle of “Whole to part”. According to this principle the largest possible rectangle of the building is found and set up first. Then it is further divided into small parts completing the major setting out for the building.

It is very important that setting out process is done in a horizontal plane. When the ground profile is not horizontal proper care must be paid to establish the setting out profiles in a one level. For simple applications a tube filled with water can be used to obtain the levels.

Main instruments involved in this process are Theodolite, Steel and Linen Tapes, Arrows, Wooden pegs, Wire nails and Nylon threads.

Theodolite used for Setting Out peg

Theodolite and Wooden Pegs used for Setting Out

After establishing the base line, the main rectangle is set up using the pegs and theodolite. Arrows are used as temporary pegs and wooden pegs are driven for permanent pegs .90° angle is taken by the theodolite and Pythagoras rule is also commonly used for the process. When using the Pythagoras rule proper care must be paid to obtain the largest possible combination of triangles for higher accuracy. Steel tape must be used to measure long distances and it must be tightly stretched when taking the readings.

Wooden pegs atop by a wire nail are driven to establish the grid lines of the building. These pegs are driven at places such that they won’t be disturbed by field work etc. Usually they are driven with a distance of 1.5 meter from the grid line.

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The diagonals of the main rectangle are checked to determine its accuracy. Accurately set up main rectangle is then subdivided to obtain the consisting gridlines. These are obtained by the using structural drawings, Theodolite and steel tape. Nylon threads are stretched between the pegs to obtain the gridlines when necessary.

Usually apart from the pegs depicting the main grid lines, pegs which show the 500mm off sets are also established during the setting out process to facilitate the construction that follows.

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