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Android 10: Know the Features of Google’s new operating system

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dmomrv
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Android 10

Google is launching its latest version of the Android operating system later called Android Q now Android 10 soon. It has been told that this new version of Android comes with many new features.

According to the news, Google will provide system-wide dark mode features in Android Q. If this feature is available, the smartphone automatically has a dark mode activate based on the external environment.

According to a website called Android Police, which provides various news and disclosures may inside secrets about Android, the Google Wide Dark Mode feature in Android 10 will set the dark mode of smartphones on auto-unmatched times in sunrise and sunset.

That means that the smartphone itself will be in dark mode when it is dark, it will come out of Dark Mode while light or sunlight.

In fact it will work like the Night Light feature in the existing Android device.

android operating system

System-Wide Dark Mode Feature may look great. But there are some shortcomings to it.

After activating this feature, it will automatically work on sunrise and sunset. This feature can not be customized by turning on or off according to your required time. That means, even when you have to visit dark places on day, the dark mode will not be activated. Although on the user feedback and complaints, Google is customizing it. And it was expected that this feature will be updated soon.

The Android, as we’ve said, is only the first hours of Love, immobilized, the hour of the ideal made eternal prisoner” ― Auguste Villiers

#Android 10

According to the Android Police, there will also be a spectacular feature featuring the device’s battery-powered device in Android 10. This feature will be activated when the phone’s battery low. This reduces the phone’s brightness and will be taken into power saving mode while the battery is low. Due to which the battery consumption on the phone will be somehow less and the battery charge will take a little longer.

According to the news, apart from these features, facial reorganization, privacy control, app verification settings, desktop mode, built-in in-screen recorder, will also be features in Android 10.

Download notes for Structure Analysis I

By
Ravi Dhami
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structure analysis

Structure Analysis is a branch of Civil Engineering that deals with the study of the behavior of structures under loads. It involves the analysis and design of building structures, bridges, towers, and other similar structures to ensure their safety, stability, and sustainability. The goal of Structure Analysis is to predict how a structure will respond to various loads, such as wind, earthquakes, and weight, and to design it in such a way that it can withstand these loads without collapsing or becoming damaged. The field encompasses a wide range of mathematical and computational methods, including Statics, Dynamics, Mechanics of Materials, and Finite Element Analysis.

Download the Complete Note Of Structure Analysis I Civil Engineering, Pokhara University.

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Notes of Structural Analysis I by Sumit Paudel

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Structure Analysis I POU Old question solution

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Download Strength Of Materials Notes

By
Ravi Dhami
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Strength Of Materials

Strength of Materials is a branch of mechanics that deals with the behavior of solid objects subjected to various types of stress and strain. It helps us to understand how the internal forces and deformations in materials affect their overall strength, stability, and ability to resist deformation. The fundamental principles of Strength of Materials (SOM) include Hooke’s law and the laws of stress and strain.

Download the Complete Note Of Strength Of Materials Civil Engineering, Pokhara University.

This is the complete note related to Strength Of Materials.

Download note here.

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SOM by Rishi Khanal

1 file(s) 41.05 MB
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SOM Notes by Arjun Bhandari

1 file(s) 63.55 MB
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If you have any note collection please feel free to share with us because your collection may help others.

Are you seeking for Syllabus of Pokhara University:

For more info about Pokhara University Visit Official Site Click Here.

Unit Weight of Materials Used at Construction Site

By
denish
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0
bricks

While doing analysis works or other calculation you need to know the units weights of individual materials. So here we made a list of 33 materials which are used for construction at sites with their unit weight.

  1. Water = 1000 Kg/ m3
  2. Bricks (broken) = 1420 Kg/ m3
  3. Bricks(common)= 1600 Kg/ m3
  4. Cement(ordinary)= 1440 Kg/ m3
  5. Cement (rapid hardening)= 1250 Kg/ m3
  6. Cement Mortar= 2000 Kg/ m3
  7. Cement Concrete (Plain)= 2400 Kg/ m3
  8. Cement Concrete (Reinforced)= 2500 Kg/ m3
  9. Glass= 2500 Kg/ m3
  10. Lime Concrete= 1900 Kg/ m3
  11. Cement Plaster= 2000 Kg/ m3
  12. Lime Plaster= 1700 Kg/ m3
  13. Stones (Ballast)= 1720 Kg/ m3
  14. Stones (Aggregates)= 1750 Kg/ m3
  15. Stones (Basalt)= 2850 Kg/ m3
  16. Stones (Granite)= 2450 Kg/ m3
  17. Stones (Marble)= 2650 Kg/ m3
  18. Timber (Oak, Sal)= 510 Kg/ m3
  19. Timber (Mango)= 650 Kg/ m3
  20. Timber (Teak)= 625 Kg/ m3
  21. Coal 600= Kg/ m3
  22. Plastics= 1250 Kg/ m3
  23. Oils= 800 Kg/ m3
  24. Ashes= 650 Kg/ m3
  25. Clinker= 750 Kg/ m3
  26. Rubber= 1300 Kg/ m3
  27. Slag= 1500 Kg/ m3
  28. Clay Soil= 1900 Kg/ m3
  29. Sand (dry)= 1540 to 1600 Kg/ m3
  30. Sand (wet)= 11760 to 2000 Kg/ m3
  31. Steel= 7850 Kg/ m3
  32. Chalk= 2100 Kg/ m3
  33. Bitumen= 1040 Kg/ m3

Download NBC Codes: Nepal National Building Code (NBC)

By
Ravi Dhami
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0
Nepal National Building Code

Nationa Building Code (NBC Codes) is a group of 23 codes. At first 20 codes are developed after that 3 codes, architectural code, electrical, and sanitation are added to NBC in 2060 B.S.

To Download NBC 105: 2020 Click Here

Why the National Building Code (NBC) is required in Nepal?

After the 2045 B.S earthquake that time his government felt that they require their own Building Code. More reasons are:

  1. Due to the lack of country code mostly engineers are forced to use other country building codes.
  2. Without considering the strength of materials people are constructing residential buildings.
  3. 10-15 years ago, about 95% of the building’s structures are built-up without taking the suggestion of any technicians or engineers.
  4. Even technicians do not have proper knowledge and idea about earthquake residential buildings.

Implementation of NBC Codes

From 2060/04/12, NBC is started to use in government and government shared construction buildings. Later in 2062/11/01 after the publish of Gadget NBC is implemented in 58 municipalities, 28 VDC where district headquarter lies at that time.

Before releasing it on government gadget to implement the NBC is started to use in Lalitpur metropolitan in 2059 B.S Magh-2 on the occasion of National Earthquake day.

Download NBC Codes: Nepal National Building Code

National Building Code (NBC) is a group of 23 codes. At first 20 codes are developed after that 3 codes, architectural code, electrical, and sanitation are added to NBC in 2060 B.S.

National Building Code(NBC) are sub categorized into 4 types:

1. International state-of-Art (SOA):

By using reference from the developed country building code you can design a building. Generally, while constructing important buildings, commercial buildings, stadium reference is taken from developed country code. It contains only one code.

Download International State-of-Art: NBC 000

2. Professionally Engineered Buildings (PEB):

Buildings having a plinth area of more than 1000 square feet or a structural span greater than 4.5-meter are categorized in Professionally Engineered Buildings (PEB). These buildings should be designed and built-in with guidelines of engineers.

Download Codes for Professionally Engineered Buildings:

NBC 102::UNIT WEIGHT OF MATERIALS

NBC 103::OCCUPANCY LOAD (IMPOSED LOAD)

NBC 104::WIND LOAD

NBC 105 ::SEISMIC DESIGN OF BUILDINGS IN NEPAL

NBC 106::SNOW LOAD

NBC 107::PROVISIONAL RECOMMENDATION ON FIRE SAFETY

NBC 108::SITE CONSIDERATION FOR SEISMIC HAZARDS

NBC 109::MASONRY : UNREINFORCED

NBC 110::PLAIN AND REINFORCED CONCRETE

NBC 111::STEEL

NBC 112::TIMBER

NBC 113::ALUMINIUM

NBC 114::CONSTRUCTION SAFETY

3. Mandatory Rule of Thumb (MRT)

The main objective of these Mandatory Rules of Thumb (MRT) is to provide ready-to-use dimensions and details for various structural and non-structural elements for up to three-storey reinforced concrete (RC), framed, ordinary residential buildings commonly being built by owner-builders in Nepal. Their purpose is to replace the non-engineered construction presently adopted with pre-engineered construction. Now, it is mandatory to follow MRT while designing or constructing buildings in every municipality of Nepal.

Download Codes of Mandatory Rules of Thumb (MRT):

201:: MANDATORY RULES OF THUMB REINFORCED CONCRETE BUILDINGS WITH MASONRY INFIL

NBC 202:: MANDATORY RULES OF THUMB LOAD BEARING MASONRY NBC L

NBC 205:: MANDATORY RULES OF THUMB REINFORCED CONCRETE BUILDINGS WITHOUT MASONRY INFILL

4. Guidelines for Remote Rural Buildings (GRB)

Guidelines for Remote Rural Buildings (GRB) guidelines are prepared in order to raise the seismic safety of low-strength masonry buildings and earthen buildings. These guidelines are intended to be implemented by the owner/builder with some assistance from the technicians.

Download Guidelines for Remote Rural Buildings (GRB) Codes:

NBC 203 ::GUIDELINES FOR EARTHQUAKE RESISTANT BUILDING CONSTRUCTION: LOW STRENGTH MASORY

NBC 204 :: GUIDELINES FOR EARTHQUAKE RESISTANT BUILDING CONSTRUCTION: EARTHEN BUILDING (EB)

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25 important points for Site Engineer

By
denish
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Civil Engineer

The basic but important points which are essential for civil engineers while working at the site are:

Important points for Site Engineer

  1. The height of the parapet wall should be 1 meter or 3 feet. 
  2. The thickness of DPC should be 25 cm or 1 inch. 
  3. The general height of the building 3.15 meters or 10 ft. 
  4. The weight of the cement bag is 50kg. 
  5. One bag of cement is equal to 0.0347 m3 or 1.25 cubic feet.
  6. Total 28.8 cement bags in the 1-meter cube. 
  7. The minimum thickness of the slab is 125 mm 5inch. 
  8. A lintel is provided in case of a brick wall at a height of 2.4 meters of thickness 15 cm minimum. 
  9. The minimum diameter of bars used in the slab is 8 mm. 
  10. The minimum diameter of bars used in the column is 12 mm.
  11. The maximum diameter of bars to be used in the slab is 1/8 of the thickness of the slab.
  12. Maximum chair spacing 1 m. 
  13. PCC is not affected by water.
  14. RCC is affected by water because of bars. 
  15. The maximum free fall of concrete is 1.5 m.
  16. The maximum water absorption of First-class brick is 15-20% of its weight.
  17. The initial setting time of cement is 30 minutes.
  18. The final setting time of cement is 10 hours ( 600 minutes).
  19. 1 gallon is equal to 3.78 liters.
  20. 1 yard = 3 feet
  21. Weight of steel = D²/162.2 Kg/m or D²/533 Kg/ft.
  22. The slope of the staircase for residential building is kept between 25° – 40°.
  23. Cement should be used within 50 days of manufacturing.
  24. The minimum curing period for concrete is 7 days in normal weather conditions and 10 days in dry and hot weather conditions.
  25. In the column, steel is taken between 0.8% to 6% of the cross-section area of the column.

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Water cement ratio of Concrete !! How to choose W/C ratio?

By
Ravi Dhami
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0
Mortar_mixed_Water_Cement

Water Cement ratio is the relative weight of water to that of cement in the concrete mixture. It is also denoted by W/C ration.

In Concrete, the water-cement ratio determines the final properties of the concrete. The Water-cement ratio is the most important factor behind the strength of concrete.

If a concrete mixture has a high water-cement ratio then it will be workable (easy to work with that concrete) but it will be less stronger as compared to the same concrete with less water-cement ration.

Less workable concrete is stronger. So, while working with cement, the ratio of water must be kept according to the nature of work to get the best result on strength as well as more workable.

You cannot have free choice for choosing the ratio of W/C because the W/C ratio needs about 0.23 to complete the hydration of cement.

If only 23% of water is added while mixing, the concrete will not be workable due to less water. So, we need to use add additional water for workability but with in limit so the strength should not be affected.

In normal concrete, W/C ratio is kept between 0.35 – 0.40 because in this ratio we get good workability without losing a lot of strength.

With the increase in W/C ratio the workability of concrete increases but after one optimum point that workability decreases due to the segregation problem in aggregate and bleeding problems in cement paste.

Relation between Water Cement ratio (W/C) and compressive strength of concrete:

  1. To increases the compressive strength of concrete you need to take a low w/c ratio.
  2. W/C ratio affects the permeability. So less W/c ration concrete is less permeable.
  3. The water-cement ration affects the drying shrinkage and cracking of concrete. If you kept a low W/C ration the drying shrinkage and cracking of concrete will low.
  4. If the w/c ratio chooses by considering workability and strength then there will be less volume change from drying and wetting.
  5. With a low W/C ratio the weather resistance of concrete increases.
  6. W/c ratio determines the concrete and reinforcement bond.

Also, the Curing of concrete helps to gain the required strength and helps to decrease the permeability of hardened concrete.

Also, read the article on Why the curing of concrete is required and different methods of the curing.

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Preventive measures of Waterlogging

By
Ashok Khanal
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water logging
EPSON DSC picture

If the productivity of land decrease with a rise in water table then the land is said to be water logged. Waterlogging is the saturation of soil with water.

Causes of waterlogging

  1. Due to over and intense irrigation.
  2. Due to inadequate natural drainage.
  3. Seepage of water from adjoining high lands.
  4. Seepage of water from the canal from the upper level.
  5. Because of the impervious layer.
  6. Irregular topography.
  7. Due to high rainfall.
  8. Land submerged due to flood.

Also Read: Advantages of irrigation system

Effects of waterlogging

  1. It decreases the production of the land.
  2. Difficulty in cultivation works.
  3. Unnecessary grass/weeds grow in the land.
  4. increase the cases of malaria in waterlogged places.
  5. decrease the temperature of the as a result bacterial activity is decreased and so does productivity.
  6. Land converted in salinity (salty land) due to waterlogging.

Preventive measure of waterlogging:

1) By reducing the intensity of irrigation.
2) By providing a drainage system.
3) By improving pre-existing or natural drainage.
4) By optimum use of water.
5) By crop rotation method.
6) By effective sub-surface drainage system.
7) By adaptation of lift irrigation or sprinkle irrigation methods at those areas where possibility of waterlogging is high.

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ETABS Shortcut keys !! Very Useful For ETABS

By
Ravi Dhami
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0
ETABS Shortcut keys

ETABS is engineering software used for structural analysis and design of buildings. In the engineering field mostly engineers prefer to work in ETABS because of its flexibility and user friendly. It is created by American based company CSI.

ETABS is very much useful for structural engineers as well as a civil engineer. For structural analysis, we use various standard codes as references that are pre-defined on ETABS. Manually it takes hours even a day or more than that to analyze and do complex calculations.

Why do you need to use ETABS?

  • It saves time as well as you need to put less effort into the structural analysis.
  • Easy and user friendly.
  • Easily you can check the stability of the structure.
  • It calculated the seismic and wind load properly.
  • You can easily find out the required amount of reinforcement.
  • You can see the 3D view of structure, plan, and elevation at the same time.

Now, lets come to the main topic of the article. While working with ETABS software if we prefer the use of shortcut keys instead of going to an individual menu for each time, it will dramatically save our time. ETABS have limited numbers of shortcut keys as compare to AutoCAD among them if we remember 20/30 shortcut keys that will be enough for design and analysis work for structures.

ETABS Shortcut Keys list :

1. File Menu

  • Ctrl+N –New Model
  • Ctrl+O – Open File
  • Ctrl+Shift+E – File Close
  • Ctrl+ S – Save File
  • Ctrl+P – Print Graphics
  • Ctrl+Shift+C – Comments and Log
  • Ctrl+Shift+F -Show Input/Output Text Files
  • Alt+F4 – Exit
  • Ctrl+Shift+5 – Capture Picture > Entire Screen
  • Ctrl+Shift+6 – Capture Picture > Current Window / Titlebar
  • Ctrl+Shift+9 – Capture Picture > Current Window as Enhanced Meta file

2. Edit Menu

  • Ctrl+Z – Undo
  • Ctrl+Y – Redo
  • Ctrl+X – Cut
  • Ctrl+C – Copy
  • Ctrl+V – Paste
  • Ctrl+R – Replicate
  • Ctrl+Shift+M – Align Joints/Frames/Edges
  • Ctrl+M – Move Joints/Frames/Shells
  • Delete – Delete

3. View Menu

  • Ctrl+Shift+F1 – Set Plan View
  • Ctrl+Shift+F2 – Set Elevation View
  • Ctrl+Shift+F3 – Set 3D View
  • Ctrl+D – Set Grid System Visibility
  • Ctrl+W – Set Display Options
  • F2 – Rubber Band Zoom
  • F3 – Restore Full View (Zoom All)
  • Shift+F2 – Zoom In One Step
  • Shift+F3 – Zoom Out One Step
  • F10 – Pan
  • Ctrl+Shift+A – Show All Objects
  • Ctrl+Shift+J – Show Selected Objects Only
  • Ctrl+Shift+W – Refresh Window
  • Ctrl+Shift+V – Refresh View

4. Select Menu

  • Ctrl+A – Select All
  • Ctrl+G – Select Groups
  • Ctrl+J – Get Previous Selection
  • Ctrl+K – Invert Selection
  • Ctrl+Q – Clear Selection
  • Ctrl+Shift+L – Intersecting Line
  • Ctrl+Shift+O – Poly
  • Ctrl+Shift+P – Intersecting Poly

5. Analyze Menu

  • F4 – Undeformed Shape
  • F5 – Run Analysis

6. Display Menu

  • F6 – Deformed Shape
  • F12 – Plot Functions
  • Ctrl+T – Show Tables
  • F7 – Force/Stress Diagrams > Support/Spring Reactions
  • F8 – Force/Stress Diagrams > Frame/Pier/Spandrel/Link Forces
  • F9 – Force/Stress Diagrams > Shell Stresses/Forces

7. Design Menu

  • Shift+F5 – Steel Frame Design > Start Design/Check
  • Ctrl+Shift+F5 – Steel Frame Design > Display Design Info
  • Shift+F6 – Concrete Frame Design > Start Design/Check
  • Ctrl+Shift+F6 – Concrete Frame Design > Display Design Info
  • Shift+F7 – Composite Beam Design > Start Design/Check
  • Ctrl+Shift+F7 – Composite Beam Design > Display Design Info
  • Shift+F8 – Composite Column Design > Start Design/Check
  • Ctrl+Shift+F8 – Composite Column Design > Display Design Info
  • Shift+F9 – Steel Connection Design > Start Design/Check
  • Ctrl+Shift+F9 – Steel Connection Design > Display Design Info
  • Shift+F10 – Shear Wall Design > Start Design/Check
  • Ctrl+Shift+F10 – Shear Wall Design > Display Design Info

8. Other shortcut keys

  • Ctrl+U – Display Unit
  • F1 – ETABS Help
  • Ctrl+L – Change Language to
Etab Shortcut Keys List
Etab ShortcutKey List – 1

You may also searching for: AutoCAD Shortcut Keys

Tips for selecting bricks? 10 quality of good bricks!

By
dmomrv
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0
bricks

Either you are a civil engineer or a contractor or owner planning to construct a building or other construction works, it is necessary for you to select the good quality of bricks as construction materials.

You do not have to build a perfect wall. You have to lay a perfect brick.

Will Smith

Like this proverb, you can not build a perfect wall without perfect bricks and other building materials. So in this article, I am sharing the tips with which you can easily select and identify the bricks of good quality.

You may also love to read: Calculation process to find the quantity of cement sand for plastering

10 tips for selecting good quality of bricks for construction work.

Follow these 10 tips/points to get the best quality of brick.

  1. Bricks should be standard size as specified per dimension (230 × 110 × 55)mm.
    • Note: The size of brick may vary from county to country.
  2. When two bricks are struck with one another, it should give clear metallic ringing sound.
  3. Bricks should be well burnt and should possess sharp edges.
  4. A good brick should not absorb water more than 20% of its dry weight. At any case absorption should not exceed 25%
  5. A good brick should possess required compressive strength should not be less than 35kg/cm2.
  6. It should be hard enough so that it is not scratched by a fingernail i.e. impression should be made on the surface.
  7. A very rough test for testing strength of brick, brick fall freely from a height about 2m on to a hard surface floor, it should not break.
  8. Specific gravity should be greater than 1.8.
  9. The brick should have uniform color and structure throughout its body.
  10. The recommended standard size of an ideal brick is 230mm-110mm-55mm which with mortar joints gives net dimensions of 240mm-120mm-65mm.

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What are the Properties of aggregates for concrete?

By
dmomrv
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0

Aggregate is the most important constituent in concrete. It is necessary for us to understand the properties of aggregates because it significantly controls the strength, durability, and volume stability of concrete.

Do you know, about three-quarters (3/4) of the volume of concrete occupies aggregates?

Properties of aggregates

The properties of aggregates determine the final properties of concrete.

i) Size of aggregates

The size of aggregates is designated by the maximum size of the individual aggregate present in a substantial amount. The aggregate is said to be of 20mm size it passes through a 20mm sieve and retained on a 16mm sieve.

Based on the size of particles, aggregates are classified as follows:

  1. Coarse aggregate: It passes through an 80mm sieve and retained on a 4.75mm sieve.
  2. Fine aggregate: It passes through a 4.75mm sieve and retained on a 75-micron sieve.
  3. Particles between 0.075mm and 0.002mm are classified as silt and particles of size smaller than 0.002mm as clay.
    1. Silt and clay are undesirable particles and should be removed from aggregates used for making concrete.

ii) Shape of aggregate

  • Aggregates are classified as rounded, irregular or partly rounded, angular and flaky.
  • The shape of the particles affects the voids in compacted aggregate.
  • Aggregate of rounded shape is very appropriate from workability consideration, but it results in poor bonding between the passes and the cement paste.
  • Flaky and elongated particles are not desirable for making concrete.

A flaky particle has thickness less than 0.6 times of mean sieve size. Mean sieve size is defined as the arithmetic average of a sieve size through which it passes and over which it is retained. Elongated particles have their longest dimension 1.8 times the mean sieve size. These particles have the highest surface area and hence reduce the workability of concrete. They tend to orient in a plane during compaction resembling with stratified rock and so affect adversely the durability of concrete.

iii) Surface Texture of aggregate

The surface texture describes the nature of the surface of the aggregate. The aggregates are classified as glossy, smooth, granular, rough, crystalline, Honey-combed and porous. The shape and surface texture of aggregates influence the strength of concrete considerably.Aggregates of a rough surface increases the strength because of the higher surface area resulting in greater adhesive force between the particles and cement paste.

However, it reduces workability on account of more water required to wet the surface of the aggregates.

iv) Compressive strength of aggregate

Generally, the strength of aggregate is greater than the strength of normal concrete. The strength of aggregate is required to be made in the following situations:

  1. For the production of high strength and ultra high strength concrete.
  2. When contemplating to use aggregates manufactured from weathered rocks.
  3. Aggregate manufactured by industrial purpose.

iv) Modulus of Elasticity of aggregate

Modulus of Elasticity of aggregate depends on its composition, texture, and structure. The modulus of elasticity of aggregate will influence the properties of concrete w.r.t. shrinkage and elastic behavior and to a very small extent creep of concrete. Many studies have been conducted to investigate the influence of modulus of elasticity of aggregate on the properties of concrete.

One of the studies indicated that the ‘E’ of aggregate has a decided effect on the elastic property of concrete and that the relation of ‘E’ of aggregate to that of the concrete is not a linear function, but maybe expressed as an equation of exponential type.

Also Read: How to determine the crushing value of aggregate?

v) Specific gravity of aggregate

In concrete technology, the specific gravity of aggregates is made use of in design calculation of concrete mixes. With the specific gravity of each constituent known, its weight can be converted into solid volume and hence a theoretical yield of concrete per unit volume can be calculated.

Specific gravity of aggregate is also required in calculating the compaction factor in connection with the workability measurements. The average specific gravity of the rocks varies from 2.6 to 2.8.

vi) Bulk density of the aggregate

The bulk density or unit weight of aggregate gives valuable information regarding the shape and grading of the aggregate. For a given specific gravity the angular aggregates show a lower bulk density. The bulk density of aggregate is measured by filling a container of known volume in the standard manner and weighing it.

Bulk density shows how densely the aggregate is packed when filled in a standard manner. The bulk density depends upon the particle size distribution and shape of the particles.

vii) Water absorption and surface moisture

Aggregates contain permeable holes through which moisture can permeate. There are four conditions of moisture content:

  1. Bone dry: When an aggregate does not contain any moisture. The condition is attained by drying aggregate at 100 degrees.
  2. Air-dry: When a saturated and surface dry aggregate is allowed to dry in air, a part of moisture evaporates and part of it is retained in the pores. This is known as air-dry aggregates. C for 24 hours.
  3. Saturated and surface dry: When all the pores in the aggregate are completely filled with moisture and there is no free moisture on its surface, it is said to be saturated and surface dry condition. This condition of aggregate is considered for the water cement ratio in the concrete mix design.
  4. Moist: When an aggregate has free moisture on its surface in addition to all pores filled, they are said to be in moist condition.

viii) Soundness

Soundness is the resistance of aggregates to physical disintegration forces such as heating and cooling, wetting and drying, freezing and thawing due to climate changes. The aggregate is said to be unsound when its volume changes due to physical disintegration forces resulting in deterioration of the concrete.

ix) Durability of aggregates

Durability is the resistance to aggregates to chemically disintegrating forces. The most common chemical reaction, causing disintegration, is between the active silica constituents of the aggregate and alkalies in the cement.

These aggregates contain veins or inclusions of reactive silica, which when used with cement having a high alkali content forms alkali–silica gel. The gel is of the unlimited swelling type which causes disintegration of the aggregate.

What aggregates are used in a huge amount in concrete?

It is normal to raise a question in the mind of fresh engineers that Why aggregates are used in a huge amount in concrete or construction works? For that, we have to understand or know the properties of aggregate. Let’s discuss the properties of aggregates briefly.

A similar type of article on the internet: WHAT ARE THE PROPERTIES OF AGGREGATES FOR CONCRETE?

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Seasoning of Timber – Methods of timber seasoning

By
dmomrv
-
1

Seasoning of timber or simply Timber seasoning is the process of drying timber or removing moisture or sap, present in a freshly felled timber, under more or less controlled conditions

Reasons for Timber Seasoning

  1. Freshly felled timber contains moisture 100 to 200% of its dry weight.
  2. A well-seasoned timber contains moisture about 10-12% of its dry weight.
  3. Seasoning should be the first step for the efficient utilization of timber.
    Objective and Advantage
  4. To minimize the tendency of timber to shrink, warp and split.
  5. To increase strength and to make timber more stable.
  6. To make timber safe from the attack of fungi and insects.
  7. To reduce the weight for transport purposes and handling.
  8. To improve the working qualities of timber.
  9. To avoids the defects in timber.
  10. To make it durable.

Method of Timber Seasoning

There are two methods for seasoning of timber.

1. Natural Seasoning of Timber

By natural process, the timber is seasoned. As compared to the artificial seasoning method, this method is time-consuming.

A. Air Seasoning

Sawn timber is stacked in a dry place about 30cm above floor level with longitudinal and cross pieces arranged one upon another, leaving space for the free circulation of air. A pitched roof covering is used to protect from direct sunlight.

Advantages Of Air Seasoning

  • Simple, easy and cheap
  • Less chance of damage.

Disadvantages Of Air Seasoning

  • The process is very slow (takes about 2 to 4 years.)
  • Large space is required.
  • It blocks the capital for a quite long period.
  • It is difficult to reduce the moisture content at our desired job.
  • Timber may get attacked by insects and fungi during the seasoning period.

B. Water Seasoning

Logs of wood are completely immersed in a running stream of water. By this process, the sap, sugar, and gum, etc. are leached out of the wood and replaced by the water. The logs and then taken out and left to dry in an open place.

Advantage Of Water Seasoning

  • It is quick to process than natural air seasoning
  • All the organic food materials present in the sapwood are washed off; the wood is less liable to be eaten away by a worm or to decay by dry rot.

Disadvantage Of Water Seasoning

  • This process reduces the elasticity and durability of the timber.
  • The timber becomes brittle.

2. Artificial Seasoning of Timber

Artificial Seasoning of timber are:

A. Kiln Seasoning

Timber is seasoned under controlled temperature and humidity conditions with proper air circulation and ventilation system. The moisture content of timber should be kept between 10 to 12 % of its dry weight.

Advantages Of Kiln Seasoning

  • Moisture content can be reduced as per requirements.
  • Well seasoned in a short span of time.
  • Less liable to shrinkage and no chance for the attack by insects and fungi.
  • Immediately used when required.

Disadvantages Of Kiln Seasoning

  • Costly and requires skilled labour.

B. Chemical Seasoning (Salt Seasoning)

Timber is immersed in a solution of salt. It is then taken out and then seasoned in an ordinary way. The interior surface of timber dries in advance of exterior one and chances of formation of external cracks are reduced.

C. Electrical Seasoning

This method works on the principle that Heat is produced when poor conductors are placed in the field of high frequency. The wooden plants are made to pass through an induction coil producing field of high frequency.

Due to the electrical induction effect, the moisture content in timber gets evaporated in a uniform way, which results in the superior quality of timber. This is an expensive process which is used to manufacture process of the plywood.

If you are confused or unclear about this topic. Kindly check out a similar type of article. Click Here !!

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Flow table Test of Concrete

By
dmomrv
-
0

Flow table test is used to determine the consistency of freshly mixed concrete by measuring its spread over a flat surface. Flow test is generally done in the laboratory to determine the fluidity of the concrete.

Apparatus Required for flow table test:

The main apparatus for the flow table test is a flow table made of steel sheet of thickness 1.5mm and a size of 750mm x 750mm.

Also, a tempering rod made of hardwood, measuring scale, and a metal mould (dia. at lower-end 200mm, upper-end 170mm, and height 200mm) is required.

Some other apparatus are:

  • Trowels or hand scoop
  • Stop-Watch (not mandatory)
  • Gloves
  • Wet-piece of cloths

Procedure for flow table test:

  1. Before start testing, clean the dust from the table and mould if present by using semi-wet cotton cloths.
  2. Place the mould in the center of the flow table usually marked.
  3. Now, with the help of a trowel or hand scoop pour the freshly mixed concrete on the mould in two layers. Each layer should be tamped approximately 25 times by the tampering rod.
  4. If excessive concrete remains on top of mould then it should be leveled off.
  5. Now, the mould is removed from the concrete by the steady vertically upward pull and let concrete stand on its own without any support in the shape of mould.
  6. The table is then raised and dropped from the height of 12.5mm about 15 times. Each drop should not be less than 2 seconds and not more than 5 seconds.
  7. At last, the diameter of the spread concrete is the average of 6 symmetrically distributed. And the average spread is noted.
flow table test formula

The value of flow(%) calculated from 0 to 150%.

https://www.youtube.com/watch?v=RO5GHlTvGnA

In this way, you can do flow table test of concrete.

Also Read: Different method for Curing of Concrete

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