Answer is D) Invar tape.

Honeycomb in concrete

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What is Honeycomb?

---**Honeycombs** are hollow spaces and cavities left in concrete mass on the surface or inside the mass where concrete could not reach. These look like honey bees nest.


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Causes of honeycomb in Concrete:

1 .Insufficient compaction to concrete.
2 .Less cover to reinforcement bars.
3 .Improper Workability in concrete
4 .Concrete already set before placing .
5 .High concrete free fall while pouring
6 .Form work not watertight/rigid.
7 .More coarse aggrgegates than designed mix proportions and over sized aggregates.
8 .Improper placement of bars at column and beam junction.
9 .Addition of more water than designed at site for achieving workability.
10 .Steel congestion not allowing concrete flow to all corner.

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🔴 TYPES OF SOIL 🔴

♦️ Aeolian soil :- Transported by wind

♦️ Alluvial soil:- Transported by river

♦️ Lacustrine soil:- Transported by lake

♦️ Marine soil:- Transported by sea

♦️ Loess:- Transported by wind

♦️ Talus:- Transported by gravitational force

♦️ Drift:- Transported by ice or glacier

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Specific gravity values for different Soils

📌 Sand :- 2.65-2.67

📌 Silty sand :- 2.67-2.7

📌 Inorganic Clay :- 2.7-2.8

📌 Soil with mica or iron :- 2.75-2.8

📌 Organic soil :- 1-2.6

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💥 Important points from thermal stresses (Strength of materials)

👉 Stresses produced due to change in temperatures(Rise/Fall) are called as thermal stresses

👉 Actual meaning of coefficient of thermal expansion is strain produced per unit change in temperature

👉 Unit of Coefficient of thermal expansion = per degree celcius

👉 Coefficient of thermal expansion for different materials
⚡ Aluminium = 24 x 10^(-6)
⚡ Copper = 17.5 x 10^(-6)
⚡ Steel = 12 x 10^(-6)

👉 Higher the value of coefficient of thermal expansion, more will be the material sensitive for temperature change

👉 For the bar free to expand, with change in temperature (rise/fall), no stress is developed

👉 Prismatic bar with rigidly supported at both ends
⚡ As temperature increases, compressive stresses are developes on bar
⚡ As temperature decreases, tensile stresses are developes on bar

👉 Copper bar is in series with steel bar
⚡ As temperature increases, compressive stresses are developed on both copper and steel bar
⚡ As temperature decreases, tensile stresses are developed on both copper and steel bar

👉 Copper plate is in parallel with steel plate and form a composite
⚡ As temperature increases, compressive stress developed on copper and tensile stress developed on steel
⚡ As temperature decreases, tensile stress developed on copper and compressive stress developed on steel

👉 Copper rod is enclosed in steel tube and both are rigidly fixed at ends
⚡ As temperature increases, Compressive stresses are developes on both copper and steel
⚡ As temperature decreases, tensile stresses are developes on both copper and steel

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Caliche : It is a sedimentary rock consist of gravel ,sand and silt, Clay.

Loam : It is a soil with roughly equal proportion of silt sand and Clay .

Taff : soft porous rock usually formed by compaction and cementation of volcanic ash or dust .

Till : Till or Glacial till is unsorted glacial sediment.

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“Today a reader, tomorrow a leader.” –

Happy reading..... 👻

🌟Instrument used in Surveying

✨Clinometer:-
Measuring angles of slopes

✨Subtence Bar:-
Measure horizontal distance.

✨Box sextant:-
Measuring horizontal angle.

✨Planimeter:-
Measuring area on map.

✨Pentagraph:-
Enlarging or reducing area on map.

✨Line Ranger:-
Ranging a chain line.

✨Hand Level:-
Making contour & Cross section of preliminary work.

✨Ceylon Ghat Tracer:-
Measuring angles of slopes & setting out grade contours.

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🔸 Types of Manometer and its applications

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🔵 Classification of soil 🔵👇

♦️Clay:- < 0.002mm

♦️Silt (0.002 mm to 0.075 mm)
1. Coarse:- 0.02 to 0.075 mm
2. Medium:- 0.01 to 0.02 mm
3. Fine:- 0.002 to 0.01 mm

♦️ Sand ( 0.075 to 4.75 mm)
1. Coarse:- 2 to 4.75 mm
2. Medium:- 0.425 to 2 mm
3. Fine:- 0.075 to 0.425 mm

♦️ Gravel ( 4.75 to 80 mm)
1. Coarse:- 20 to 80 mm
2. Fine:- 4.75 to 20 mm

♦️ Coble:- ( 80 to 300 mm)

♦️ Boulder:- > 300 mm

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♦️Grades of concrete♦️

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Fire demand

🔸 Kulching's Formula :- 3182√P

🔸 Buston's Formula :- 5663√P

🔸 Freeman's Formula :- 1136(P/5 + 10)

🔸 National board of fire underwriters formula :- 4637√P(1-0.01√P)

Where, P = Population in thousands.

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