👉CAUSES OF CRACKS IN CONCRETE YOU SHOULD
KNOW @engineer03
.
Cracking is one of the most common problems in concrete and it should be avoided seriously. *Different causes of
cracks in concrete
are described below:
1. SHRINKAGE:
Shrinkage is one of the major causes of cracking in hardened concrete. In drying shrinkage, the volume of concrete is gradually decreased and if the component is restrained against free movement, tensile stresses are developed which causes cracks.
2. TEMPERATURE CHANGES: The temperature variation in concrete results in the
differential volume change. When the tensile strain capacity of
concrete exceeds
due to the differential volume change, it will crack.
3. CHEMICAL REACTION:
Due to the alkaline nature of cement, it reacts with
the carbon dioxide
(CO2) present in the atmosphere resulting in an
appreciable increase
in the volume of the materials which finally leads to cracking.
4. POOR CONSTRUCTION PRACTICES:
Poor construction practices such as adding
excessive water to the
mix, lack of curing, poor compaction, using low-
grade materials, unreasonable placements of construction joints etc.
are also responsible for cracking in concrete.
5. ERRORS IN DESIGN & DETAILING:
Errors in design and detailing such as an
inadequate amount of
reinforcement, improper design of foundation,
precast members and
slabs, improper selection of materials, lack of
sufficient contraction
joints etc may result in excessive cracking.
6. CONSTRUCTION OVERLOADS & EARLY
FORMWORK REMOVAL:
The load induced in the structure during
construction can also lead to cracking especially at the younger stage when the formwork is
removed earlier.
7. ELASTIC DEFORMATION AND CREEP:
The different components of the building such as
wall, column, beam.
slab etc undergo elastic deformation when loaded.
The deformation of
concrete depends on the type of building materials
used in the construconstruction bricks, cement concrete
blocks etc. This
unusual deformation of concrete results in cracking.
8. CORROSION OF CONCRETE:
The corrosion of steel develops a huge amount of iron oxides and
hydroxide that have a much greater volume than the volume of metallic iron.
👇👇👇👇
@engineersWorks

✔️answer this quation with the explanation
👇👇
@engineersWorks
@engineersWorks
@engineersWorks

Questions with Answers Part 1 @engineersWorks
.
Q1. What is the Unit Weight of concrete?
A:- The unit weight of concrete depends on the type of aggregates and amount of voids. As per IS : 456-200 Unit weight of PCC is 24KN/m3 and RCC
is 25KN/m3
Q2. What is the unit weight of Steel?
A. The unit weight of Steel is 78.5KN/m3
Q3. What are the Nominal Concrete Mix proportions
for different grades:
A. Important: C-15 - 1:2:4 and C-5 - 1:4:8,C-20 and C-25 - 1:2:3,
(Cement:Sand:aggregate)
Q4. What is ductility?
A. Ductility is the Ability to deform under tensile
stress.
Q5. How to find the weight of steel bar used in
reinforcement?
A. Weight of Bar in kg/m = Dsquare/162.2 D- Dia
of bar in mm
Q6. What’s the difference between one-way slab
and two-way slab?
A. One way slab: Ratio of Longer Span / Shorter
span > 2 Two way slab: Ratio of Longer span/ shorter span <= 2
Q7. What is flat slab?
A. The slab which is supported on columns (Flab slab don’t have beams)
Q8. What do you mean by One storeyed, Two
storeyed building?
A. The building which has two floors is called two
storeyed building.
Q9. What’s the height of each floor?
A. 3m
Q10. What’s the length of rise and tread in Stair
case?
A. Rise – 150mm to 200mm, Tread – 250mm to 300mm
Q11. What’s the slope of Staircase?
A. As per IS 456, the slope or pitch of stair should
be between 25 degrees to 40 degrees.
Q12. What do you mean by the moment of inertia?
A. A quantity expressing a body’s tendency to resist
angular acceleration, which is the sum of the
products of the mass of each particle in the body
with the square of its distance from the axis of
rotation.
Q13. What is a crank length in the slab?
A. The crank length in Slab is 0.42 D. Where D is
Depth of Slab- Top cover – Bottom Cover.
Q14. What are the types of a slump?
A. True Slump: The concrete mass after the test when slumps evenly all around without disintegration is called the true slump.
*Shear Slump: When one-half of the concrete mass
slide down the other is called the shear slump. This type of slump is obtained in a lean concrete mix.
*Collapse Slump: When the sample is collapsed due to adding excessive water, it is known as collapse slump.
*Zero Slump: For very stiff or dry mixes it does not
show any changes of the slump after removing the
slump cone.
Q15. What is honeycomb in concrete? How is it
formed? How to eradicate honey comb in concrete?
A. Learn about Honeycomb concrete –
Q16. What is grouting?
A. Grout is a fluid form of concrete which is used
to fill the voids.
Q17. What is allowable moisture content in Fine
aggregate for the concrete mix?
A. We won’t use the aggregate if its moisture
content is more than 5%.
Q18. What do you mean by segregation?
A. Segregation is a separation of cement, sand from aggregate. This is caused due to Water
cement ratio and when concrete is poured about
more than 1.5m
Q19. What is Seepage?
A. Slow percolation of water through soil is called
Seepage.
Q20. What is the Compressive Strength of brick?
A. Second class brick-70kg/cm2
First class brick-105kg/cm2 Fire brick-125kg/cm2
Q21. How do you check the quality of cement on
the site?
A. 1. Date of Mfg: Cement strength decreases with
its age.
2. Color: Colour should be grey with light greenish
shade and it should be uniform. Color gives an
indication of excess lime or clay.
3. Float test: A good cement won’t float if you
throw a cement in water.
4. When you put your hand in cement bag you
should feel cool.
Q22. 1BHK full form : 1 Bedroom, 1 Hall, 1kitchen
Q23. What are the Different types of Slabs?
A. There are 16+ different types of slabs –
Q24. What is Initial & final setting time of concrete?
A. Intial Setting time : 30mins, Final setting time : 10hrs
Q25. What is durability?
A. Ability to withstand under pressure is called
Durability.
Q26. What are the concrete tests?
A. Slump test, Compressive strength test, water permeability test, Water absorption test
🚩ይቀጥላል ...
@engineersWorks

👉part 2 ከ ቅድም የቀጠለ @engineersWorks
.
Q27. What is bleeding in concrete?
A. Bleeding is one form of segregation, where water
comes out to the surface of the concrete, being
lowest specific gravity among all.
Q28. What is the name of the machine to get
compression test?
A. Universal testing machine (UTM)
Q29. When we go for Pile foundation?
A. Pile foundation is adopted when the Soil bearing capacity is less than 24KN/M3
Q30. What is the function of stirrups in the column?
A. Stirrups are provided to handle the shear force
and to hold the rebars (main bars)
.
CLEAR COVER TO MAIN REINFORCEMENT:
1. FOOTINGS : 50 mm
2. RAFT FOUNDATION.TOP : 50 mm
3. RAFT FOUNDATION.BOTTOM/SIDES : 75 mm
4. STRAP BEAM : 50 mm
5. GRADE SLAB : 20 mm
6. COLUMN : 40 mm
7. SHEAR WALL : 25 mm
8. BEAMS : 25 mm
9. SLABS : 15 mm
10. FLAT SLAB : 20 mm
11. STAIRCASE : 15 mm
12. RET. WALL : 20/ 25 mm on earth
13. WATER RETAINING STRUCTURES : 20/30 mm
.
WEIGHT OF ROD PER METER LENGTH:
DIA WEIGHT PER METER
6mm = 0.222Kg
8mm = 0.395 Kg
10mm = 0.616 Kg
12mm = 0.888 Kg
16mm = 1.578 Kg
20mm = 2.466 Kg
25mm = 3.853 Kg
32mm = 6.313 Kg
40mm = 9.865 Kg
1bag cement-50kg
1feet-0.3048m
1m-3.28ft
1sq.m-10.76sq.f t
1cu.m-35.28cu.ft
.
STANDARD CONVERSION FACTORS
INCH = 25.4 MILLIMETRE
FOOT = 0.3048 METRE
YARD = 0.9144 METRE
MILE = 1.6093 KILOMETER
ACRE = 0.4047 HECTARE
POUND = 0.4536 KILOGRAM
DEGREE FARENHEIT X 5/9 – 32 = DEGREE
CELSIUS
MILLIMETRE= 0.0394 INCH
METRE = 3.2808FOOT
METRE = 1.0936YARD
.
UNIT WEIGHT:
01. Concrete 25 kN/m3
02. Brick 19 kN/m3
03. Steel 7850 Kg/m3
04. Water 1000 Lt/m3
05. Cement 1440 Kg/m3
06. 1Gallon 3.78 Litres
07. Link 8" = 200mm
08. 1 Hectare 2.471 acr(10000m2)
09. 1 Acr 4046.82m2 = 100 cent
👇👇👇👇
@engineersWorks

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👉@engineer03

👉How To Solve Waterproofing Problems Before Painting @engineer03
.
➡Dampness of walls and water seepage are common problems faced by homeowners.
*This happens due to poor quality construction and lack of waterproofing measures during construction of the home. *It can cause dampness of the walls, efflorescence (puffy white deposits on walls) and peeling of paint These dampness problems need to be tacked for a good home painting experience.
*There seems to be a lot of confusion on what waterproofing chemicals need to be used and the process involved. So, we decided to write this guide to set matters straight. In writing this blog we consulted Mr. Rajkiran
Gupta, a waterproofing expert from Shri Krishna Associates who gave us a detailed explanation of waterproofing problems.
*waterproofing issues and their causes, what waterproofing chemicals need to be used and
waterproofing procedures that need to be followed. We have covered solutions and fixes for existing buildings. Preventive measures that are to be taken during construction of buildings will be covered later in another post.
Navigation Menu
1) How to treat rising damp Rising damp affects the lower region of walls
because of rising ground water within the wall
due to capillary action. This causes efflorescence (white deposit) and peeling of the paint.
*Solution: Treating Mild Dampness in Interior Wall
Treating Severe Dampness in Interior Wall
2) How to treat water seepage on walls because of adjoining bathroom or kitchen Walls on the other side of bathroom or kitchen walls get damp because of either leaking
pipes or seepage through tile grout.
*Solution
Waterproofing Tile Cracks & Grout in Bathroom
or Kitchen Treating Mild Dampness on Adjacent Wall Treating Severe Dampness on Adjacent Wall
3) How to treat dampness due to water seepage from exterior walls Defects and cracks in the exterior walls causes water seepage to the interior walls.
*This affects mid-level of interior walls and areas around window frames.
Solution
Repairing & Waterproofing Exterior Wall Treating Mild Dampness in Interior Wall
Treating Severe Dampness in Interior Wall
4) How to treat dampness on ceiling due to leakage from terrace Improper or inadequate waterproofing of the terrace can lead to water seepage on the roof
especially around the upper corners of the room.
Solution
Roof Waterproofing method
5) Dampness Due to Seepage From Bathroom on the Floor Above
Dampness in the interior walls and ceiling can also arise because of leakages from the kitchen or bathroom of the apartment above.
*Solution
Waterproofing Solution for Kitchen or Bathroom.
.
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══════════════
@engineer03

👉Difference between 43 Grade Cement and 53 Grade Cement @engineer03
.
*Portland Cement (OPC) is
graded according to their strength.
*The grade indicates the compression strength (mpa) of the concrete that
will attain after 28 days of setting.
*Compression Strength:
Cement grade indicates the compression strength of the cement concrete after 28 days of setting.
*43 Grade Cement attains compression strength of 43 mpa (megapascals) in
28 days of setting compared to 53 mpa attained by 53 Grade cement.
*Initial Strength: 53 Grade cement are used for fast
paced construction were initial strength is to be achieved quickly.
*53 Grade cement has fast setting compared to 43-grade cement.
*53 Grade attains 27 mpa in 7 days compared to 23 mpa by 43-grade cement.
👉Uses & Application:
*53 Grade OPC cement is Used in RCC and pre-stressed concrete of higher
grades, cement grouts, instant plugging mortars etc. where initial higher strength is the criteria.
*43 Grade OPC Cement is commonly used for plastering works, Non-RCC structures, pathways etc where initial setting time is not of importance.

👉Today Tip @engineer03
.
▶In a one-way slab, why do we not provide torsion reinforcement as in a two-way slab, put in corners?
➡ANSWER
*Because two way slab deflects both ways towards centre it experiences uplift at corners and to prevent that
you need to provide corner reinforcement but in one way slab deflection is going to happen only in one direction(shorter direction) thus no uplift at corners and no corner reinforcement required. Hope this answers your query.

👇👇👇👇
@engineersWorks

↪️Understanding Grades of Concrete @engineersWorks
.
➡Grades of concrete are defined by the strength
composition of the concrete, and the minimum strength the concrete should have following 28 of initial construction.
✔️The grade of concrete is
understood in measurements of MPa, where C stands for compressive strength and the MPa denotes the overal strength.
✔️Concrete mixes are defined in ascending numb
of 5, starting at 10, and show the compressive
strength of the concrete after 28 days. For inst
C-10 has the strength of 10 newtons, C-15 has t
strength of 15 newtons, C-20 has 20 newtons
strength and so on.
✔️Different mixes (M) come in various mix proportions of the various ingredients of cement sand and coarse aggregates. For instance, C-20 comes in the respective ratio of 1:2:3
.
✔️Generally :-👇
▶C-5 used for Lean concreat
.
▶C-10 Used for: Patio slabs, pathways and non structure work
.
▶C-15 Used for: Pavement kerbs and floor blinding(Ground Slab)
.
▶C-20 Used for: Domestic floors and foundations (with the weight of structure will be lighter).
✔️Also go for workshop bases, garages, driveways and into floor slabs.
.
▶C-25 Used for: Construction in all areas. Multi-purpo concrete mix, usually used for foundations.
.
▶C-30 Used for: Pathways and roadways (this is the
lowest grade concrete mix that can be used for purpose).
✔️More durable than the grades that come before, and thus is much more weather- resistant and can take heavy road traffic.
.
▶C-35 Used for: Commercial structures. This heavy concrete mix is usually used for creating extern walls and slabs, as well as for structural piling.
.
▶C-40 Used for: Commercial construction sites, foundations and beams for structural support a roads.

The most durable in this list, C-40 can withstand chemical corrosion also, so is frequently used on farms where slurry could corrode structures, or in septic tanks.
.

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👉Tip📝 @engineer03

👉Tip📝 @engineer03

👉Tip📝 @engineer03