OPTIMUM COMPACTION WET & DRY - civil engineering vk

Optimum Compaction Wet and dry 

Dry of Optimum Compaction and Wet of Optimum compaction

Comparing between and dry and wet of optimum compaction

Properties changes with compaction	Dry optimum	Wet of Optimum
Structure after compaction	Flocculated (Random)	Dispersed (Oriented)
Water deficiency	More	Less
Permeability	More,  Isotropic	Less,  Isotropic
Compressibility
at low stress	Low	Higher
at high stress	High	Lower
Swelleability	High	Low
Shrinkage	Low	High
Stress strain Behavior	Brittle,high peak, Higher elastic modulus	Ductile, No peak, Lower elastic modulus.
Strength (undrained) as mould after saturation	High	Much lower
Construction Pore Water  Pressure	Low	High

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Sensitivity of the Soil related to shear strength in Laboratory test - Civil Engineering Study VK

SENSITIVITY OF SOIL - Soil Mechanics

Sensitivity elated to shear strength of soil in Laboratory test

•     It is defined as the ratio of undisturbed strength to that of the remoulded strength

•     Sensitivity = Undisturbed Strength / Remoulded Strength

Sensitivity of Soil

Sensitivity	Nature of Soil
1	Insensitive
1 to 4	Normal
4 to 8	Sensitive
8 to 16	Extra -Sensitive
>16	Quick

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TYPES OF TEST ON BRICKS - IS code 3495 - civil engineering study

TYPES OF TEST ON BRICKS - civil engineering study

Types of Tests On Bricks IS code 3495 

Following tests are conducted on bricks to determine its suitability for construction work.

• Absorption test
• Crushing strength test
• Hardness test
• Shape and size
• Color test
• Soundness test
• Structure of brick
• Presence of soluble salts (Efflorescence Test)

 

 WATER Absorption Test on Bricks - 3495 PART 2

• Absorption test is conducted on brick to find out the amount of moisture content absorbed by brick under extreme conditions. 

Apparatus:

• Oven, 
• Weight balance, 
• Tray

PROCEDURE

• Take any five random bricks from a lot of brick as a specimen.
• Dry the specimen in a ventilated oven at a temperature of 105°C to 115°C till it achieves considerably constant mass.
• Cool the specimen to room temperature and take its weight (M1).

Testing:

• When the specimen is completely dry, then immerse it in the clean water at the room temperature (27 ±2°C) for 24 hours.
• Remove the specimen from the water after 24 hours and wipe out water with a damp cloth and weigh the specimen.
• Take the weight (M2) of the specimen after 3 minutes of removing from the water.
• Points to be Taken Care:

• When you take M1, If the Specimen is warm while touching, it shall not be used for the test. Test it when you feel it cool.

Result:

• Note down the M1 and M2.
• Percentage of Water absorption of brick by its mass, after 24-hour immersion in cold water is calculated by the following formula
• (M2-M1)/M1*100

• For a good quality brick the amount of water absorption should not exceed 20% of weight of dry brick.

TYPE                         WATER ABSORBTION

FIRST CLASS         < 20%     OR 15% AVERAGE

SECOND CLASS     < 22.5%  OR 20% AVERAGE

THIRD CLASS         < 25%      OR 25% AVERAGE

 

Crushing Strength or Compressive Strength Test on Bricks - IS 3495 PART 1

• Place the specimen with flat face s horizontal and mortar filled face facing upwards between plates of the testing machine.
• Apply load axially at a uniform rate of 14 N/mm2 (140 kg/cm2) per minute till failure occurs and note maximum load at failure.
• The load at failure is maximum load at which the specimen fails to produce any further increase in the indicator reading on the testing machine.

•  Compressive Strength of Bricks = Maximum Load at Failure (N)/Average area of bed face (mm2)
• The average of result shall be reported.

• Crushing strength of bricks is determined by placing brick in compression testing machine. 
• After placing the brick in compression testing machine, apply load on it until brick breaks. 
• Note down the value of failure load and find out the crushing strength value of brick. 

compressive strength in N/mm2

>10.5     first class

7.5  second class

5.5  third class

 

compressive strength of common bricks should not be used if it is  less than 3.5N/mm2

 

 

Bricks Class Designation	Average compressive strength of Bricks
	Not less than (N/mm2)	Less than (N/mm2)
350	35	40
300	30	35
250	25	30
200	20	25
175	17.5	20
150	15	17.5
125	12.5	15
100	10	12.5
75	7.5	10
50	5	7.5
35	3.5	5

 

Efflorescence Test on Bricks - IS 3495 PART - 3

• A good quality brick should not contain any soluble salts in it. 
• If soluble salts are there, then it will cause efflorescence on brick surfaces.

Type	area affected
Nill Effloresence	Very Low
Slight	0-10%
Moderate	10-50%
Heavy	>50%
Serious	>50% + deposit are  present in powder forms Heavy Flakes

 

WARPAGE TEST - IS 3495 PART 4

• check the bricks for warpage of brick like concave and convex warpage with the help of glass or stell surface

 

Hardness Test on Bricks

• A good brick should resist scratches against sharp things. 
• So, for this test a sharp tool or finger nail is used to make scratch on brick.
•  If there is no scratch impression on brick then it is said to be hard brick.

for any doubt finger nail means

 

Shape and Size Test on Bricks (dimension test) - IS 1077

• Shape and size of bricks are very important consideration. All bricks used for construction should be of same size. The shape of bricks should be purely rectangular with sharp edges.
• Standard brick size consists length x breadth x height as 19cm x 9cm x 9cm.
• To perform this test, select 20 bricks randomly from brick group and stack them along its length , breadth and height and compare. 
• So, if all bricks similar size then they are qualified for construction work.

 

Dimension Test

Dimension should not greater than below value Length -19×20= 380 ± 12 cm Breadth - 9×20 = 180 ± 6 cm Height - 9×20 = 180 ± 6 cm here 20 indicate 20 no of bricks used in sample

 

Color Test of Bricks

• A good brick should possess bright and uniform RED color throughout its body.

 

Soundness Test of Bricks

• Soundness test of bricks shows the nature of bricks against sudden impact.
• In this test, 2 bricks are chosen randomly and struck with one another. 
• Then sound produced should be clear bell ringing sound and brick should not break. 
• Then it is said to be good brick.Soundness Test of Bricks

 

Structure of Bricks

• To know the structure of brick, pick one brick randomly from the group and break it. 
• Observe the inner portion of brick clearly. It should be free from lumps and homogeneous.Structure of Bricks

 

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What are the properties of high density concrete in dry state?

High density Concrete

• 1. High density concrete is those concrete which have best packaging with the presence of finest to coarse particles of substance of concrete which gives best denseness of concrete.

• 2. It is achieved by using the knowledge of concrete with skills.

• 3. It is achieved by using of some admixtures or additionally use of special ingredients of concrete

• 4. For making high density concrete first step is choosing the right materials for it.

• 5. It requires heavier aggregates with specific gravity of 3.5 to 4.which give

• 6. Some Natural aggregates used in High dense concrete is Limonite, Haematite, Magnetite,Barite etc.

• 7. like finest grade of cement.small to higher proportion of fine to coarse aggregate which gives better packaging of concrete and most important part is using of water reducing agent which removes extra part of water some plasticize,skilled labor who knows how to mix it.

• 8.for mixing or preparation first coarsest aggregate is spread on floor then finer particles are spread over it in order of their degree and after that mix thoroughly till homogenous mix obtain after that water and plasticizer are used.

• 9. now we ready for making high density concrete 

• 10. for next steps we want some form-work and compaction instruments which imparts the density of concrete. during these process some precautions are taken like taking the precaution for not having segregation, bleeding, too much water, honey combing, too much time taken for preparing and using of green concrete etc.

How to know what is high density concrete

• For knowing what is high density concrete and where is it use and how it works we must know all about the Properties of high dense Concrete.

Properties of high density Concrete

1. It is highly durable.

2. It Have highest toughness. 

3. It is impermeable.

4.Sulfate resisting properties, 

5. It is heavier than other concrete work

6. It have very high mechanical properties as strength and durability.

• Strength of concrete at 28 days - greater than 40MPa
• coefficient of thermal expansion is almost twice than normal concrete
• shrinkage is about 1/4 to 1/3rd of normal concrete

7. High Shielding properties from all radiations and other mechanical forces.

8. It reduces the intensity of neutrons, gama and other rays by absorbing its particles and gives shield against radiation on nuclear projects. and shield are electronic instruments from high temperature and radiations.

9. Ease of Constructions due to its process of manufacturing.

10. weight of High density concrete is very high in the range of 3360 to 3900 kg/m3

11. It is Highly Dense - 

• Higher the density of concrete higher the absorption of radiation

12. Absense of air voids

For more you should read on following link page

Types and Properties

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CIVIL ENGINEERING SUBJECTS

LIST OF ALL SUBJECTS RELATED TO CIVIL ENGINEERING STUDY

We provide list of all the civil engineering subjects which is essentials and without it no one never be a civil engineering.... Students who study or will study in college still reads these following subject.

• Engineering Mechanics

• Environmental Engineering

• Soil Mechanics

• Concrete Technology

• Reinforced concrete construction (RCC)

• Strength of Material (SOM)

• Structural Steel Engineering

• Structure Analysis

• Solid Waste Management

• Structural Engineering Design

• Fluid Mechanics

• Irrigation Engineering

• Surveying or Survey Engineering

• Engineering Mathematics 

• Geo-technical Engineering

• Applied Physics

• Engineering Chemistry

• Elements of Electrical Engineering

• Engineering Drawing and Planing

• Building Materials

• Building Construction

• Foundation Engineering

• Construction Management

• Waste Water Management

all the above subjects and its syllabus which is most important related to civil engineering exams and practices are discussed later with another posts

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