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አድራሻ፦  ቁ 1.መርካቶ
                ቁ.2 አየር ጤና  ኪዳነ ምህረት

ጥራትና ታማኝነት መለያችን ነው።
ታምራት ፕሌት እና ጄ ቦልት አቅራቢ

👉Causes and Prevention of Segregation

🚧separation of the constituents of a heterogeneous mixture so that their distribution is no longer uniform.

⏺In the case of concrete, it is the differences in the size of particles and in the specific gravity of the mix constituents that are the primary causes of segregation, but its extent can be controlled by the choice of suitable grading and by care in handling.

⏺It is worth noting that a higher viscosity of the fresh cement paste component militates against the downward movement of the heavier aggregate particles;consequently, mixes with low water/ cement ratios are less prone to segregation.

🏗There are two forms of segregation.

*In the first, the coarser particles tend to separate out because they tend to travel further along a slope or to settle more than finer particles.
*The second form of segregation, occurring particularly in
wet mixes, is manifested by the separation of grout
(cement plus water) from the mix.
With some gradings, when a lean mix is used, the first type of segregation may occur if the mix is too dry;addition of water would improve the cohesion of the mix,but when the mix becomes too wet the second type of segregation would take place.

⏺The actual extent of segregation depends on the method of handling and placing of concrete.

⏺If the concrete does not have far to travel and is transferred directly from the skip or bucket to the final position in the form, the danger of segregation is small.

⏺On the other hand, dropping concrete from a considerable height, passing along a chute, particularly with changes of direction, and discharging against an obstacle – all these encourage segregation so that under such circumstances a particularly cohesive mix should be used .

🏷For more information click this Link Below And Subscribe Our YouTube Channel👇

https://youtube.com/@ethiopianconstruction7?si=ils307xXQQpIdCwG

@etconp

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🔅 ፕሌት any Size & thickness
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                ቁ.2 አየር ጤና  ኪዳነ ምህረት

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🚧ከ1,140 በላይ በአጥር የተዘጉ የውስጥ ለውስጥ መንገዶች ተከፍተዋል።

የአዲስ አበባ ከተማ መንገዶች ባለሥልጣን፤ ከታህሳስ 14 ጀምሮ በ1 ሺህ 143 ሥፍራዎች የተዘጉ መንገዶችን በማስከፈት ለሁሉም የህብረተሰብ ክፍል አገልግሎት እንዲሰጡ አድርጓል፡፡

400 የሚሆኑት በግብረ-ኃይል እንዲነሱ የተደረገ ሲሆን፣ 720 የሚሆኑት ደግሞ ባለሥልጣን መስሪያ ቤቱ ባስተላለፈው ጥሪ መሰረት ህብረተሰቡ በራሱ ያነሳቸው ናቸው፡፡

ከዚህም በተጨማሪ 685 ኮለኖች እና 11 ኬላዎችም በግብረ ኃይል የዘመቻ ሥራ ተነስተዋል፡፡

በቀጣይም ህብረተሰቡ በራሱ ጊዜ አጥሮችን እንዲያነሳ ባለሥልጣን መስሪያ ቤቱ በድጋሚ አሳስቧል፡፡

Via አዲስ አበባ መንገዶች ባለስልጣን

@etconp

👉 INTERCON Construction Chemicals 

● Concrete Admixtures
● Bonding Agents
● Waterproofings
● Wall Putty, Prime Coat
● Concrete Repair Mortar
● Floor hardener, Epoxy
● Grout, Self-level mortar
● Quartz paint, Contextra
● Tile Adhesive & Tile Joint Fillers 
● Geotextiles and other construction chemicals and materials

☎️ Tel: 0961955555

🔹 Address 1: Signal road, around
Dinberwa Hospital

🔹 Addres 2: Wellosefer, Infront of
Dani Plaza

👉What is a Construction Joint?

🚧A construction joint is a planned joint made in concrete when concrete placing is stopped and later resumed.

💫It is not a crack and not a failure — it’s an intentional joint created because concrete work cannot always be completed in one continuous pour.

📜In simple words:

⏺Where today’s concrete meets tomorrow’s concrete = construction joint
⏺Why Construction Joints Are Needed
⏺Construction joints are required due to:Limited working time of concrete (setting time)
⏺Large volume of concrete
End of working day Equipment or labor limitations Planned stage-by-stage construction Without a proper construction joint, the structure may develop weak planes and leakage paths.

🎲Location of Construction Joints
⏺Construction joints must be placed where stresses are minimum.

📍Common locations:
⏺Beams: Near the mid-span (not near supports)
⏺Slabs: Along beam lines or at one-third span
⏺Columns: Just below the beam or slab level
⏺Walls: Horizontal joints at floor levels
⏺Footings: Usually avoided, but if needed, placed horizontally

⚠️ Construction joints should never be placed randomly.

🏷Types of Construction Joints

🚧1. Vertical Construction Joint
⏺Used in walls and long slabs
Concrete is stopped vertically
Surface is roughened for bonding

🚧2. Horizontal Construction Joint

⏺Common in columns and walls
⏺Occurs when concreting is done in lifts
⏺How a Construction Joint Is Made (Step-by-Step)
⏺Stop concreting at a planned location
⏺Allow concrete to partially set
⏺Roughen the surface
Wire brush
⏺Chipping
⏺Clean the surface
⏺Remove laitance, dust, loose particles
⏺Apply bonding agent
⏺Cement slurry or epoxy bonding agent
⏺Place fresh concrete
⏺Proper compaction and curing

⚡️This process ensures monolithic behavior (acts like one piece).

⏺Bonding Methods at Construction Joint
⏺Cement Slurry Method
Cement : Water = creamy paste
⏺Applied just before new concrete
⏺Economical and common
Epoxy Bonding Agent
⏺High bonding strength
Used in critical structural members
⏺Costlier but more effective
Difference Between Construction Joint and Expansion Joint

🚧Feature

⏺Construction Joint
⏺Expansion Joint

🏷Purpose

⏺Due to stopping work
⏺Due to thermal movement
Planned

🎲Advantages of Construction Joints

✔ Allows large structures to be built in stages
✔ Prevents uncontrolled cracking
✔ Maintains structural integrity
✔ Reduces construction difficulty
Disadvantages (If Poorly Done)

❌ Weak bond between old and new concrete
❌ Cracks at joint location
❌ Water leakage
❌ Reduced durability

🔰Key Precautions

⏺Always plan joint locations
⏺Surface must be rough and clean
⏺Use proper bonding agent
⏺Never pour fresh concrete on dry dusty surface
⏺Ensure proper vibration

🌟Final Note

⏺A construction joint is not a defect when:
✔ It is planned
✔ Properly prepared
✔ Properly bonded

⏺When done correctly, the structure behaves as one solid unit.

@etconp

👉What do we mean by workability of concrete?

🚧What factors do affect it?

🚧How do we know if a concrete is too workable?

🚧Is there any scientific way of knowing degree of workability of a concrete?

📜Workability of concrete is defined as the ease and homogeneity with which a freshly mixed concrete or mortar can be mixed, placed, compacted and finished. Strictly, it is the
amount of useful internal work necessary to produce 100% compaction.

Another similar term used to describe a freshly prepared concrete is ‘consistency’ which is the ease with which it will flow. It is the wetness of the concrete and the measure of fluidity or mobility.

Wet concretes are more workable than dry concrete, but concretes of the same consistency may vary in workability.

A concrete which has high consistency and which is more mobile, need not be of right workability for a
particular job.

Type of work, thickness of section, reinforcements and mode of compaction are the aspects to be considered while specifying the workability for any particular job.

Workable concrete shows very less internal friction between particles and overcomes the frictional resistance with just the amount of compacting efforts provided.

Workability of the concrete depends on a number of interrelating factors.

Water content, aggregate properties, use of admixtures, fineness of cement are the factors affecting workability.

1. Water content: The increase in watercontent increases the fluidity of the concrete thus providing greater lubrication.

2. Size of aggregates: The surface area of bigger aggregates is less and hence less amount of water is required for lubricating the surface to reduce the friction. Thus the concrete having large sized aggregate is more workable (of course, within certain limits) And other properties of aggregate will affect the workability of concrete.

3. Mix proportions: Aggregate/cement ratio is the measure of how lean or rich the concrete is.

If aggregate/ cement ratio is
higher, the concrete becomes leaner.

In lean concrete less paste is available for the lubrication of the aggregate, while in rich
concrete with low a/c ratio, more paste is available which makes the mix more
cohesive and hence provides better workability.

4. Use of admixtures: Use of admixtures in concrete is the major factor that affects the workability.

The use of plasticizers and super-plasticizers amply increase the workability of the concrete.

Air entraining
agents produce air bubbles which act as rollers between particles and provide better mobility thus improving the workability.

5. Time and temperature: Fresh concrete gets stiffened as the time flows.

This is because some of the water used to mix the concrete gets evaporated and some gets absorbed by the aggregates.

Thus the workability of concrete reduces with time.

This loss of workability with time is known as slump
loss.

The effect of temperature on workability of concrete is noteworthy.

As the temperature increases, the workability of the mix reduces.

💫Measurements of Workability/ workability Tests:

-Slump Test
-Compacting Factor Test
-Vee-Bee Test
-Flow Test
-Kelly Ball Test

🏷For more information click this Link Below And Subscribe Our YouTube Channel👇

https://youtube.com/@ethiopianconstruction7?si=ils307xXQQpIdCwG

@etconp

👉 INTERCON Construction Chemicals 

● Concrete Admixtures
● Bonding Agents
● Waterproofings
● Wall Putty, Prime Coat
● Concrete Repair Mortar
● Floor hardener, Epoxy
● Grout, Self-level mortar
● Quartz paint, Contextra
● Tile Adhesive & Tile Joint Fillers 
● Geotextiles and other construction chemicals and materials

☎️ Tel: 0961955555

🔹 Address 1: Signal road, around
Dinberwa Hospital

🔹 Addres 2: Wellosefer, Infront of
Dani Plaza