Method of concrete compression test with 150mmx150mmx150mm cube samples

In concrete compression test, usually 150mmx150mmx150mm concrete cube samples are arranged for performing test. Can 100mmx100mmx100mm concrete cube samples be applied in the test in place of 150mmx150mmx150mm concrete cube samples?

Fundamentally, the force delivered by a concrete compression machine belongs to a definite value. When normal concrete strength is used i.e. under 50MPa, the stress delivered by a 150mmx150mmx150mm cube is adequate for the machine to crush the concrete sample.

However, when the designed concrete strength is 100MPa, under the equivalent force(about2,000kN) delivered by the machine, the stress under a 150mmx150mmx150mm cube inadequate to crush the concrete cube.

So,100mmx100mmx100mm concrete cubes can be utilized in place of 150mmx150mmx150mm cubes to raise the applied stress to crush the concrete cubes. For normal concrete strength, the cube size of 150mmx150mmx150mm is already adequate for the crushing strength of the machine.

Cube Test:

Tools and Materials: Concrete cube mould with size 150mm or 100mm. It is utilized for aggregate size not surpassing 40mm and 25mm. Cube mould for test should be done from steel or cast iron having smooth inside surface. Every mould should contain steel plate to support and to resist leakage.

Compacting steel rod having 16mm diameter and 600mm length.

Compression test machine:

Methods: Mould and base plate should be properly cleansed and used with oil so that the concrete can’t fix to the side of the cube. Base plate is connected with the mould with bolt and nut.

Fill the cube with concrete in three layers.

Each layer should be consolidated for 25 times. This method is performed systematically and compaction is performed consistently to all the surfaces of the concrete. Compaction can also be performed with machine.

The surface of concrete should be flattened to maintain the identical level with the upper side of the mould. The cubes produced at construction site should be covered with plastic cover for a period of 24 hours prior to disassemble the moulds.

Once remoulded is completed, the concrete cubes are drowned in water for curing.

Compression strength test should be conducted for concrete at age 7, 14, and 28 days with compression test machine.

Result: Record the Strength value of each cube and compare with the targeted strength value. The objective of conducting the concrete test on 7 th day and the 14 th day is to forecast whether the concrete could attain the targeted 28 th day strength. Normally, the concrete would have obtained 70% strength on the 7 th day.

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Published By
Rajib Dey
www.constructioncost.co
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What should be the qualities for becoming a successful civil engineer

In order to become a successful civil engineer, the following qualities are essential :-

1. TESTS OF BUILDING MATERIALS: An efficient civil engineer should be well versed with various test methods of building materials. Given below, the details of some crucial test methods :-

Concrete Test: Slump test, compression test, split tensile test, soundness etc.
Soil Test: Core cutter test, compaction test, sand replacement test, tri axial test, consolidation test etc.
Bitumen Test: Ductility test, softening point test, gravity test, penetration test etc.

2. EXAMINATION OF SOIL: Prior to build up a construction, different types of soil tests are accomplished to define the settlement and constancy of soils. Therefore, as a civil engineer, one should possess adequate knowledge with these tests to carry on at the job site.

3. APPLICAIONS OF SURVEYING INSTRUMENTS: Each civil engineer should have clear conception on how to apply various surveying instruments like the total station, theodolite etc. These instruments are specifically designed for marking and measurements.

4. STANDARD CODES USED IN CONSTRUCTION: Each country should contain their standard safety specifications (eg: Is Code) for construction associated works. The construction works of new buildings should abide by the rules and processes indicated in the standard codes. if not, there are chances for collapsing of the structure any time.

5. BAR BENDING SCHEDULE: Bar bending schedule is a vital chart for civil engineers. It offers the reinforcement calculation of RC beam like cutting length, type of bending, the length of bending etc.

6. DRAWING AND DESIGN: Drawing and design are considered as the elementary part of a running project. It offers all the necessary specifications of that project. Each site engineers should possess the quality for evaluating such drawings and designs.

7. COMPUTATION AND BILLS: A civil engineer should have the skills to produce the estimation and bills in a construction project.

8. QUALITY CONTROL: With proper quality control, the profit of the project is raised and the cost is decreased. Therefore, a engineer should be well versed with quality control process.

9. ON SITE MANAGEMENT: A engineer should have adequate knowledge with form-work, concreting, safety measures etc.

10. COORDINATION WITH LABOR: As a civil engineer, one should know how to manage the labors in a job site.



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Published By
Rajib Dey
www.constructioncost.co
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How to perform slump cone test for testing the workability of concrete

This construction video tutorial is based on slump cone test. It is one of the most recognized field tests on fresh concrete.

Slump test is undertaken to evaluate the functionality of fresh concrete as well as verify the water ratio and the consistency of concrete from batch to batch.

The instruments which are used in slump test comprise of a mould shaped like the frustum of a cone having the following dimensions :-

Bottom Diameter : 200 mm
Top Diameter : 100 mm
Height : 300 mm
Tamping rod of steel should contain diameter of 16 mm, 600 mm long and rounded at one end.

The following methods are used to work out slump :-

nternally and externally cleanse the inner surface of mould without applying any grease or oil.

Fill the mould with concrete in 4 layers.

Tamp each later with 25 strokes of the rod to get rid of bubbles and voids.

Allocate the strokes consistently over the whole cross-section of the mould.

The rod should infiltrate each bottom-line layer.

By applying a trowel, eliminate surplus concrete after the top layer.

Take away mould gradually and vertically.

The concrete will slump or slide.

Calculate the slump height in mm.

To maintain normal functionality, the slump should not be over 50 mm.

Cleanse the slump cone.

To get more detailed information, go through the following video tutorial.

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Published By

Rajib Dey

www.constructioncost.co

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Tips to compute the quantity of cement, sand and aggregate in concrete & water cement ratio

In this construction video tutorial you will learn how to work out the quantity of cement, sand and aggregate in concrete and water cement ratio.

To do it, you should have clear conceptions on the following items :-

Grades of concrete Mix Ratio

M10 - 1:8:6
M15 - 1:2:4
M20 - 1:1.5:3
M25 - 1:1:2

Here, M means Mix and number means the compressive characteristics strength of concrete in 28 days.

Water Cement Ratio :- Grade of cement Water per bag (50 kg) cement (weight of 1 bag cement is 50 kg)

M5 - 60 litre
M7.5 - 45 litre
M10 - 34 litre
M15 - 32 litre
M20 - 30 litre

For calculation purpose, wet volume of concrete = 1 m3

Dry volume = 54% increase by weight volume
Wet volume = 100% + 54% = 154%
In order to covert it to numbers, just divide by 100
154/100 = 1.54

So, dry volume is 1.54 x wet volume
Now, you have to provide the density of cement, fine aggregates and course aggregates as follow :-
Cement = 1440 Kg
Fine Aggregate = 1450 to 1600 Kg/m3
Course Aggregate = 1450 to 1500 Kg/m3

Now, on the basis of the above dimensions, you can start calculation for the different grades of concrete. To know the detailed calculation process, watch the following video tutorial.

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Published By
Rajib Dey
www.constructioncost.co
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Brief overview of concrete mix ratio

If cement is blended with sand, stone/aggregates and water, a paste will be developed and it can be applied to stick the building materials collectively. This paste is known as concrete.

The ration upon which the cement, sand, stones or aggregates are amalgamated, defines the strength of the concrete mix. Depending on these ratios, different types of concrete grades are accessible in the market. These concrete grades range from M10, M20, M30, M35, etc.

“M” denotes “mix”. Mix characterizes concrete with indicated ratios of cement, sand and aggregate. And the number after “M” denotes compressive strength of that concrete mix in N/mm2 after 28 days. As for instance, for M30 grade of concrete mix, its compressive strength after 28 days should have been 30 N/mm2.

Concrete mix ratio table

Given below, the standard chart table that displays different grades of concrete mix design together with their relevant ratios of cement, sand and aggregates required.

It is found that volume of sand is always retained half of that of aggregates in these standard mix designs. These proportions can be estimated and sustained with buckets or some other standard cubes which are easily utilized during the project. It is essential to keep up uniformity in each and every concrete mix produced throughout the entire project.

The site engineer/supervisor should take the responsibility to examine and implement it.

Water content ratio in concrete mix: The strength & adaptability of concrete is mainly dependent on water content. The adaptability of concrete (more fluid) will be increased with the higher quantity of water but it will decrease the concrete strength.

Contrarily, if the amount of water is low, adaptability of water will also be decreased. So, it becomes complicated to arrange such concrete in the structure. Required amount of water may differ for same volume of concrete for different grades of concrete. So, equilibrium should be maintained in the construction site throughout concrete mixing.

Video Source: Civil Engineering

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Published By
Rajib Dey
www.constructioncost.co
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What should be the qualities of a qualified civil engineers

1. TESTS OF BUILDING MATERIALS:

A qualified civil engineer should be well familiar with various tests of building materials. Given below, detailed lists of some vital tests.

 Concrete Test: Slump test, compression test, split tensile test, soundness etc.
 Soil Test: Core cutter test, compaction test, sand replacement test, triaxial test, consolidation test etc.
 Bitumen Test: Ductility test, softening point test, gravity test, penetration test etc.

2. Examination OF SOIL:

Prior to develop a construction, different types of soil tests are done for finding out the settlement and strength of soils before starting a construction. Therefore, a civil engineer must contain sound knowledge regarding these tests which are carried out at the jobsite.

3. Application OF SURVEYING Tools:

A civil engineer should be well versed with utilizing various surveying instruments like the total station, theodolite etc. These instruments can be applied for marking and perfect measurements.

4. STANDARD CODES utilized IN CONSTRUCTION:

Each country contains their own standard safety specifications (eg: Is Code) for performing various activities associated with construction. There are various types of rules and methods in the standard codes and these are followed to build up new construction. If not, there are risks factors for collapsing of a structure.

5. BAR BENDING SCHEDULE:

Bar bending schedule is considered as a crucial chart for civil engineers. It helps to make the reinforcement calculation for RC beam that ranges from cutting length, type of bending, the length of bending etc.

6. DRAWING AND DESIGN:

Drawing and design are considered as the pillars of a project in-progress. It offers all the necessary specifications of that project. Each site engineers must have the capability to efficiently analyze such drawings and designs.

7. ESTIMATION AND BILLS:

A civil engineer should be able to prepare estimation and bills toward a construction project.

8. QUALITY CONTROL:

Quality control maintains the profit of a project by lessening the additional costs. Therefore, a civil engineer should contain the fundamental knowledge of quality control.

9. ON FIELD MANAGEMENT:

A civil engineer should have clear ideas on form-work, concreting, safety measures etc.

10. COORDINATION WITH LABOR:

A civil engineer should have the capability to manage labors efficiently in a jobsite.

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Published By

Rajib Dey

www.constructioncost.co

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