Important Notes
Building material Civil Engineering
Content on this page
- About OPC,
- Standard IS code for RCC,
- Ultrasonic pulse velocity test for concrete,
- Slump test,
- Slump value,
- Steel and its content,
- Workability,
- Different Type of slump,
- Admixtures and its example,
- Water used in RCC,
- Plasticizer,
- Soundness test etc.
The approximate composition of iron oxide in ordinary Portland cement is about _____ 0.5% to 6%
Oxide and its Percentage Content On Ordinary Portland cement
CaO 60 - 67
Si02 17 - 25
Al2O3 03 - 08
Fe2O3 0.5 - 6.0
MgO 0.1 - 4.0
Alkalies 0.4 - 1.3 (K2O, Na2O) alkalies
SO3 1.3 - 3.0
In India, concrete mix design for RCC is carried out using IS _______ code. 10262
The various Indian Standard code related to cement and concrete test, mix design, etc.
IS 10070 – 1982: Specification for machine for abrasion testing of coarse aggregates
IS 10079 – 1982: Specification for cylindrical metal measures for use in tests of aggregates and concrete
IS 10086 – 1982: Specification for moulds for use in tests of cement and concrete
IS 10262 – 2009: Guidelines for concrete mix proportioning
IS 10510 – 1983: Specification for vee-bee consistometer
IS 10850 – 1984: Specification for apparatus for measurement of water retaintivity of masonry cement
IS 10890 – 1984: Specification for planetary mixer used in tests of cement and pozzolana
IS 11262 – 1985: Specification for calorimeter for determination of heat of hydration of hydraulic cement
Ultrasonic pulse velocity test of concrete:
It is a non-destructive test. The ultrasonic pulse velocity method as described for green concrete can also be used to determine the strength of hardened concrete. The flaws, quality of concrete, reinforcement, moisture content, temperature of concrete materials etc. affect the pulse velocity and suitable adjustments should be made in evaluating the concrete strength. Ultrasonic pulse velocity test is not used to measure the strength of wet concrete.
Quality of concrete and pulse velocity:
General condition Pulse velocity(m/sec)
Excellent Above 5000
Good 4000-5000
Questionable 3000-4000
Poor 2000-3000
Workability:
The ease and homogeneity with which a freshly prepared concrete can be mixed, placed, compacted and finished are called workability.
For low workability concrete, the most suitable test is either Vee-bee Consistometer test or Compaction factor test.
As mentioned, its a complex property which involves many factors concerning the good workable concrete. To test the freshly mixed concrete workability, the following tests are usually performed on field and lab.
- Slump test
- Kelly ball test
- K slump test
- Vee bee consistometer test
- Flow table test.
- Compaction factor test
Important Points:
For highly workable concrete, the most suitable test is a flow table test.
For medium workable concrete, slump cone test is favourable.
J-Ring Test is conducted to check whether the given concrete sample is self-compacting concrete or not.
Slump test
A slump test is the simplest test to determine the workability of concrete, involves low cost and provides immediate results.
It is used to measure the consistency/plasticity of the concrete mix.
IS 456 has given the following values of slumps for different workability of concrete.
Degree of Workability |
Slump value in mm |
---|---|
Very low | Less than 25 |
low | 25-75 |
medium | 50-100 |
high | 75-100 |
very high' | 100 – 150 |
Different types of slump
Collapse slump:
Shear Slump:
True Slump:
Zero Slump:
Flow table test of concrete to test workability of concrete
Flow table test of concrete:
Apparatus of Flow Table Test:
Procedure of flow table test:
- Prepare concrete as per mix design and place the flow table on a horizontal surface.
- Clean the dust or other gritty material on Flow table and Sprinkle a hand of water on it.
- Now place the metal cone at the middle portion of the flow table and stand on it.
- Pour the freshly mixed concrete in the mould comprising two layers; each layer should be tamped with tamping rod for 25times. After tamping the last layer, the overflowed concrete on the cone is struck off using a trowel.
- Slowly, lift the mould vertically up & let concrete stand on its own without any support.
- The flow table is raised at the height of 12.5mm and dropped. The same is repeated for 15times in 15secs.
- Measure the spread of concrete in Diameter using centimetre scale horizontally and vertically. The arithmetic mean of the two diameters shall be the measurement of flow in millimetres.
Formula for Flow value of concrete:
- Flow value of concrete = (D1+D2)/2
Air entrained concrete
Properties improved are:
Types of air entraining agents used in concrete are:
Property of water used for making concrete:
Soundness Test:
For quality control of Portland cement, the test essentially done is
1) Le Chatelier Test:
2) Blaine Air Permeability:
4) The Vicat Apparatus:
5) Tensile (Briquette) Testing Machine:
As per IS 1077:1992, clause 4.1:
As per IS 1077: 1992, clause 7.3,
Cement
Some other type of admixtures:
Plasticizers
superplasticizer
Example:
Retarders
Example:
Accelerators
Example:
Air-entraining admixture
Example:
Thermoplastic
The different types of thermoplastic are
Polyvinyl chloride (PVC):
Advantages:
The physical property of steel such as ductility, elasticity, strength, etc are influenced by the following three factors:
The usual composition of steel should be:
There are 3 methods of Ferro cementing are as follows :
Closed Mould system :
- Several layers of meshes are tied together against the surface of the mould which holds them in position while mortar is being filled in. The mould may be removed after curing or may remain in position as a permanent part of a finished structure.
Integrated Mould system :
- Using minimum reinforcement any integral mould is first to be considered to act as a framework. On this mould layers of meshes are fixed on either side and plastering is done onto them from both sides. Precaution should be taken to have firm connection between the mould and the layers filled in later, so that finished product as a whole integral structural unit.
Armature Method :
- In this method the skeleton steel is welded to the desired shape on either of sides of which are tied several layers of stretched meshes. This is strong enough, so that mortar can be filled in by pressing for one side and temporarily supporting from the other side
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