👉Fresh concrete cracking Few Hours after casting is a common issue, typically caused by plastic shrinkage, early drying, or improper curing. Here’s a breakdown of why it happens and the solutions to prevent it:

🔍 Reasons Why Concrete Cracks After Few Hours

🏷Plastic Shrinkage Cracks

⏺Occurs when water evaporates too quickly from the surface.
⏺Common in hot, dry, or windy conditions.
⏺The surface dries faster than the inner concrete, causing shrinkage and cracking.

🏷Rapid Drying / Lack of Curing

⏺Without proper curing, moisture evaporates too fast.
Causes the concrete to shrink and crack prematurely.

🏷Excessive Water in Mix (High Water-Cement Ratio)

⏺More water = more bleeding (water rises to the surface).

⏺Leads to weak surface and higher shrinkage, which causes cracks as it dries.

🏷Settlement Cracks

⏺If concrete settles unevenly due to:Inadequate compaction.
Obstructions (like rebar) preventing uniform settlement.

🏷Temperature Effects

⏺High ambient temperatures accelerate water loss and hydration.
⏺Early thermal stresses can cause cracking before concrete gains strength.

💫Solutions to Prevent Cracking

🔰Proper Curing (Start Early!)
Begin curing as soon as surface hardens (within a few hours).

🔰Use: Wet hessian/jute cloths
Water spraying
⏺Curing compounds
Plastic sheeting

❇️Control the Environment
Avoid casting in: Very hot,Windy,Dry weather
⏺Use sunshades, windbreaks, or misting to reduce evaporation.

🔰Adjust Mix Design

⏺Use a low water-cement ratio.
⏺Add admixtures like water reducers or retarders to improve workability without excess water.
⏺Use Evaporation Retardants
Spray these over concrete right after screeding to slow moisture loss.
⏺Apply Control Joints
Cut joints within 6–12 hours (or as specified) to allow controlled cracking.
⏺Proper Compaction and Finishing
⏺Ensure vibration and finishing are done correctly to avoid air pockets and segregation.

@etconp

👉Types of cracks in concrete

💫1. Plastic shrinkage cracks

⏺Appearance: Narrow, shallow, usually parallel surface cracks that appear within hours of placing concrete.

⏺Cause: Rapid moisture loss from fresh concrete (wind, heat, low humidity).

⏺Severity/repair: Mostly cosmetic if shallow — broom finish, lite patching, or surface sealant. Prevent with curing and wind breaks.

💫2. Drying (shrinkage) cracks

⏺Appearance: Random fine to moderate cracks across the slab; often develop within days/weeks.

⏺Cause: Volume reduction as concrete dries and cures (internal restraint increases tensile stress).

⏺Severity/repair: Usually non-structural if narrow (<0.3–0.5 mm). Wider cracks may need routing & sealing or epoxy. Control with joints and proper mix/water content.

💫3. Settlement (subsidence) cracks

⏺Appearance: Wider cracks, often at one edge of a slab or wall; may be diagonal or stepped.

⏺Cause: Uneven support/soil settlement under the concrete.

⏺Severity/repair: Can be structural — investigate soil/support. Repair ranges from filling/sealing to underpinning or replacement.

💫4. Thermal cracks

⏺Appearance: Cracks due to temperature gradients — can be random or follow plane of temperature differential.

⏺Cause: Expansion/contraction from temperature changes, especially with poor jointing.

⏺Severity/repair: Often controlled with joints; repair with sealants or overlays if non-structural.

💫5. Structural (overload) cracks — flexural & shear
Appearance:

⏺Flexural: Vertical cracks at mid-span of beams/slabs, perpendicular to tensile stress.

⏺Shear: Diagonal cracks near supports.

⏺Cause: Loads exceeding design capacity or reinforcement failure.

⏺Severity/repair: Potentially serious — require structural assessment.

⏺Repairs: strengthening (carbon fiber, steel plates), additional reinforcement, epoxy injection for non-moving cracks, or member replacement.

💫6. Map or pattern cracking (crazing)

⏺Appearance: Very fine, shallow network of surface cracks (looks like crazing or a map).

⏺Cause: Rapid drying of surface or improper finishing (too much water on surface).

⏺Severity/repair: Mostly cosmetic — surface treatments, overlays, or sealers. Prevent with proper finishing and curing.

💫7. Alkali–Silica Reaction (ASR) / reactive aggregate cracking

⏺Appearance: Random map-like cracking, often accompanied by a gel exudate and expansion.

⏺Cause: Chemical reaction between alkalis in cement and reactive silica in aggregates + moisture.

⏺Severity/repair: Can be progressive and structural. Mitigation requires diagnosis; repair options limited — control moisture, use inhibitors, or replace affected concrete.

💫8. Corrosion-induced cracking

⏺Appearance: Cracking and spalling from reinforcement locations; rust stains common.

⏺Cause: Corrosion of steel rebar expands and cracks surrounding concrete.

⏺Severity/repair: Serious — needs exposure and repair of corroded steel, corrosion protection, patching, or replacement.

💫9. Freeze–thaw damage cracks

⏺Appearance: Rough, scaling, and small cracks over time; surface delamination.

⏺Cause: Freeze–thaw cycles in saturated concrete without proper air entrainment.

⏺Severity/repair: Prevent with air entrainment and proper air-void system; repair by resurfacing or replacing damaged areas.

💫10. Construction / cold-joint cracks

⏺Appearance: Crack at plane where fresh concrete was placed against hardened concrete — often vertical/linear.

⏺Cause: Lack of bond due to delays in placement.
Severity/repair: Can be non-structural or allow water ingress. Repair by cleaning and sealing, grout injection, or dowel installation.

💫11. Curling / warping cracks
Appearance: Cracking at slab corners/edges; slabs lift or curl at edges causing diagonal cracks.

@etconp

👉ሰለም የዚህ ቻናል ቤተሰቦቻችን

💫ከዚህ በኋላ የ Construction Engineering Field ሶፍትዌር በቂ ክህሎት ያላቹ የ Remote Online ስራዎች ይዘንላቹ እንመጣለን

🚧ለዛሬ 205 ካሬ G+1 Building ሙሉ Structural Analysis በ ETABS መስራት የሚችል @Mossedh ይፃፉልን🙏

@etconp

👉What is Asphalt Road Construction?

💫Asphalt road construction involves the use of asphalt, a mixture of aggregates, binder, and filler, to build and maintain roads, highways, and other pavement surfaces.

🚧The components of asphalt include aggregates, binder, and filler.

⏺Aggregates are the inert materials that provide strength and bulk to the asphalt mixture. Common aggregates used include crushed rock, sand, gravel, or slags.

⏺The binder is the adhesive substance that holds the aggregates together, with bitumen being the most common binder used.

⏺Fillers are fine materials that fill the gaps between the aggregates and binder, such as limestone dust, cement, or hydrated lime.

🏷The asphalt mixture is created by combining the aggregates, binder, and filler in specific proportions.

⏺The mixture is then heated to a high temperature (around 300°F) to facilitate mixing and application.

❇️The asphalt road construction process typically involves several steps.

⏺First, the site is prepared by clearing the area, removing debris, and grading the surface. Next, a layer of compacted aggregate material is laid down to provide a stable base.

⏺The heated asphalt mixture is then applied to the base course using a paver or spreader.

🔰After the asphalt mixture is applied, it is compacted using rollers or compactors to achieve the desired density and smoothness.

🚧Finally, the surface is finished with a layer of asphalt emulsion or sealcoat to protect it from the elements.

⏺Asphalt road construction is used for a wide range of applications, including highways and roads, parking areas, railway tracks, ports and airport runways, bicycle lanes and sidewalks, and playgrounds and sports areas.

⏺Asphalt is a popular choice for road construction due to its durability, flexibility, and resistance to heavy traffic and harsh weather conditions.

@etconp

ምንፈለገው ሰው አግኝተናል🙏

ቀጣይ ስራ ሲኖር እናሳውቃቹዋለን❤

ADVERTISMENT

ታምራት ፕሌት እና ጄ ቦልት አቅራቢ

✅የምንሰጣቸው አገልግሎቶች

🔅 ፕሌት any Size & thickness
🔅 ጄ ቦልት (ጥርስ ማዉጣትና ማጠፍ)

🔅 የተለያዩ  [modefic] ስራዎችን እንሰራለን።

♦️ ማንኛዉንም ብረታ ብረት እንገዛለን።

☎️ስልክ 0904040477 ወይም 0911016833 ደውለው ያግኙን
📱ቴሌግራም ላይ ፦https://t.me/heavenic1

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

ጥራትና ታማኝነት መለያችን ነው።
ታምራት ፕሌት እና ጄ ቦልት አቅራቢ

👉የስኮላርሺፕ እድል (Scholarship Tip)

https://t.me/ETCONpWORK/5016

👉የዓለማችን ግዙፍ የቴክኖሎጂ ተቋማት
የኤ.አይ መሰረተ ልማት ለማስፋፋት እየሰሩ ነው።

💫ኢንቪዲያና ኦፕን ኤ.አይ የ100 ቢ. ዶላር ስምምነት አድርገዋል።

🚧በኤ.አይ ቴክኖሎጂ ዘርፍ የሚሰሩ ተቋማት ለቴክኖሎጂው ትግበራ የሚያስፈልጉ መሰረተ ልማቶችን ለማምረት የሚያስችሉ ስምምነቶችን እያደረጉ መሆኑን ሮይተርስ አስነብቧል፡፡

ግዙፉ የቺፕ አምራች ኩባንያ ኢንቪዲያ እና ኦፕን ኤ.አይ የዳታ ሴንተር ቺፖችን ለማምረት የሚያስችል የ100ቢሊዮን ዶላር ስምምነት አድርገዋል፡፡ በሌላ በኩል፤ ሜታ ኩባንያን በመጪዎቹ አመታት የክላውድ ኮምፒውቲንግ ተጠቃሚ የሚያደርግ የ20 ቢሊዮን ዶላር ስምምነት ከኦራክል ኩባንያ ጋር ተፈርሟል፡፡

ሜታ እና ጉግል በክላውድ ኮምፒውቲንግ ላይ ለመስራት የ10 ቢሊዮን ዶላር ስምምነት ማሰራቸው የሚታወስ ነው፡፡ የቴስላ ኩባንያ ፈጣን የቴክኖሎጂውን ቺፖች ለመጠቀም የሚያስችለውን ስምምነት ከሳምሰንግ ጋር በ16.5 ቢሊዮን ዶላር ተፈራርሟል፡፡

በአሜሪካ የተዋወቀው እና ሶፍትባንክ፣ ኦፕን ኤ.አይ እንዲሁም ኦራክል በጋራ የሚሰሩት ስታርጌት ፕሮጀክት 500 ቢሊየን ዶላር የተመደበለት መሆኑ አይዘነጋም፡፡

በያዝነው የፈረንጆቹ አመት ተፅዕኖ ፈጣሪ የዘርፉ አንቀሳቃሽ ኩባንያዎች፣ ለቴክኖሎጂው እድገት አጋዥ የሆኑ ስምምነቶች አድርገዋል፡፡ በተለያዩ ጊዜያት የተደረጉት እነዚህ ስምምነቶች፣ በፍጥነት እያደገ የሚገኘዉን የኤ.አይ ቴክኖሎጂ አብሮ ለማልማት አስፈላጊ የሆኑ መሰረተ ልማቶችን የመገንባት ፍላጎት እያደገ ስለመሆኑ አመላካች ነው ሲል የኢትዮጵያ አርቴፊሻል ኢንተለጀንስ ኢንስቲቲዩት አስነብቧል፡፡

@etconp

👉 Dead Load vs Live Load (ACI Code)

🟩 Dead Load (DL):

⏺Permanent load on a structure.

⏺Includes self-weight of beams, slabs, columns, walls, and finishes.

⏺Does not change during building life.

⏺ACI Factor (USD): 1.2 × DL

🟥 Live Load (LL):

▶️Temporary or movable load.

📍Includes weight of people, furniture, vehicles, wind, or snow.

🔰Varies with usage or time.

▶️ACI Factor (USD): 1.6 × LL

✅ Design Load Combination (ACI 318): 1.2 DL + 1.6 LL

📘 Summary:

▶️DL = Permanent load (structure weight)

🎲LL = Variable load (occupancy & use)

#CivilEngineering
#StructuralDesign
#ConstructionKnowledge
#BuildingDesignTips
#CivilWorks
#EngineeringBasics
#EducationalContent
#EngineeringVibes
#LearnCivilEngineering

@etconp

👉What is Slump Test and Why It Matters?

📌Definition: The Slump Test is a simple test used to measure the workability and consistency
of fresh concrete before placing it in formwork.

💫Purpose:

• To check the uniformity of concrete from batch to batch.

• To ensure proper water-cement ratio and desired workability.
Equipment Used:

• Slump cone (300mm high, 200mm bottom dia, 100mm top dia)

• Tamping rod (16mm dia, 600mm long)

• Base plate and measuring scale

📜Procedure:

1. Fill the cone with fresh concrete in 3 layers, each tamped 25 times.

2. Remove the cone vertically and measure the subsidence (slump) of concrete.

3. The difference in height gives the slump value (in mm).

⭐️Types of Slump:

• True Slump – Concrete subsides uniformly.
• Shear Slump – Concrete slides sideways (indicates poor cohesion).
• Collapse Slump – Concrete completely collapses (too wet mix).
Typical Slump Values:
• Mass Concrete: 25–50 mm
• Reinforced Foundation: 50–100 mm
• Slabs & Beams: 75–125 mm
• Pumped Concrete: 100–150 mm

💥Importance:

⏺The slump test ensures proper workability, reduces segregation risk, and confirms concrete quality before casting.

#SlumpTest #ConcreteTesting #WorkabilityTest #CivilEngineering #QualityControl
#ConstructionSite #FreshConcrete #SiteEngineer #ConcreteWork
#EngineeringKnowledge

@etconp

👉TESTS FOR SAND

💫1. Sieve Analysis Test

⏺Used to determine the particle size distribution of sand. Pass sand through sieves
(4.75 mm to 150 µm). Helps to classify as fine, medium, or coarse.

💫2. Silt Content Test

⏺Determines the percentage of silt or clay in sand.
⏺Mix 50 ml sand with 50 ml water in a cylinder, shake, and settle for 3–4 hours.
⏺Silt should not exceed 8%.

💫3. Bulking of Sand Test

⏺Checks the increase in sand volume due to moisture.
⏺Add small amount of water
and note the volume change. Normal bulking = 10–25%.

💫4. Specific Gravity Test

⏺Determines density ratio of sand compared to water. Ideal specific gravity = 2.6 –2.7.

💫5. Organic Impurities Test

⏺Checks for organic matter or clay.
⏺Mix sand with NaOH solution; brown color indicates impurities.

💫6. Moisture Content Test

⏺Finds the amount of water in sand.
⏺Dry the sample at 110°C and calculate moisture % using weight difference.

💫7. Fineness Modulus Test

⏺Indicates sand quality and gradation.
⏺FM = (Cumulative % retained on sieves) /100. Fine sand = 2.2–2.6, Coarse = 2.6–2.9.

🏷Good quality sand ensures strong and durable concrete.

#MaterialTesting
#SandTesting
#QualityControl
#LabTesting
#SoilAndSand
#BuildingMaterialsTest
#ConstructionTesting
#ConcreteQuality
#SiltContentTest
#SieveAnalysis

@etconp