Field Test of Compressive Strength of Concrete | Calculation | Concrete strength test

Field Test of Compressive Strength of Concrete | Calculation | Concrete strength test
Compressive Strength of Concrete
The compressive strength of concrete is a measure of the concrete’s ability to resist loads which tend to compress it.
• A force is applied to the top and bottom of a test sample, until the sample fractures or is deformed.
• The compressive strength is determined by loading moulded concrete specimens (either cubes or cylinders) in uniaxial compression until ultimate failure.
• Normally, strength of cylinder specimen is taken as 0.8 times the strength of cube.
• Compressive strength depends on a number of factors - w/c ratio, cement content, characteristics of cement, type and properties of aggregate, degree of compaction, curing, age at the time of testing, testing conditions, ambient conditions, specimen geometry, rate of loading etc.
Determination of Compressive Strength of Concrete:
• The compressive strength of concrete is given in terms of the characteristic compressive strength of 150 mm size cubes tested at 28 days (fck) as per Indian Standards.
• The characteristic compressive strength is defined as the strength of the concrete below which not more than 5% of the test results are expected to fall.
 Procedure as per IS: 519 - 2013:
• Cube Casting:
• Dry proportion of ingredients (Cement, Sand and Coarse Aggregate) as per the design requirements shall be measured and thoroughly mixed to obtain the uniform mixture.
• Designed quantity of water to the dry proportion (water-cement ratio) shall be mixed well to obtain uniform concrete mix.
• The Concrete in the cube mould of size 150 × 150 × 150 mm shall be filled. The concrete shall be filled into the mould in layers approximately 5 cm deep. Each layer shall be compacted either by hand or by vibration. Each layer with not less than 35 strokes per layer using a tamping rod shall be compacted.
• The top of the concrete shall be finished by trowel and tapped well till the cement slurry comes to the top of the cubes.
• At least three specimens. preferably from different batches. shall be made for testing at each selected age.
Curing:
• The test specimens shall be stored in a place, free from vibration, in moist air of at least 90 percent relative humidity and at a temperature of 27° ± 2°C for 24 hours ± ½ hour from the time of addition of water to the dry ingredients.
• The specimen from the mould shall be removed after 24 hours.
• The specimen shall be kept submerged under fresh water at 27oc ± 2oc. The specimen shall be kept for 7 or 28 days. Every 7 days the water shall be renewed.
• The specimen shall be removed from the water 30 minutes prior to the testing.
• The specimen shall be in dry condition before conducting the testing.
• The Cube weight should not be less than 8.1 Kgs.
• Testing:
• The specimen shall now be placed into the Compression Testing Machine.
• The specimen shall be placed in the machine in such a manner that the load shall be applied to opposite sides of the cubes as cast, i.e. not to the top and bottom. The axes of the specimen shall be carefully aligned with the centre of thrust of the spherically seated platen.
• The load shall be applied to the specimen axially. No packing shall be used between the faces of the test specimen and the steel platen of the testing machine.
• The load shall be applied without shock and increased continuously at a rate of approximately 140kg/cm2 per minute till the cube collapses.
• The maximum load applied to the specimen shall then be recorded. The maximum load at which the specimen breaks is taken as a Compressive Load.
Calculation:
• Compressive Strength of Concrete = Maximum compressive Load / Cross Sectional Area
• Cross Sectional Area = 150mm X 150mm = 22500 mm2 or 225 cm2
• Assume the compression load is 450 KN,
• Compressive Strength = (450000 N / 225) / 9.81 = 204 kg /cm2 (Note - 1 kg is equal to 9.81 N)
• Compressive Strength of Concrete shall be expressed to the nearest kg / cm2. Average of three values shall be taken as the representative of the batch provided the individual variation is not more than +/-15 percent of the average. Otherwise repeat tests shall be made.
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[@cementaffairs1803]

आदरणीय सर आपका बहुत-बहुत धन्यवाद 🙏🏼🙏🏼
हमारा ज्ञान बढ़ाने में आप का बहुत बड़ा योगदान है 🙏🏼🙏🏼

[@hit4558]

Sir please make a video on Support roller Bending Moment and Shell Profiling

[@creativearts255]

Jiyada tar cube fail hote hain. Rmc lab stuid banate hain.micro silka dalne se streingh theek mil jata hai

[@riteshkumarlifeje9885]

Sir 25 times tap kare ge na hai total 100 times

[@creativearts255]

55 new ton mean what.

[@chandankushwaha1446]

Yes sir cement plant gyani sir

[@jksingh66]

🙏

[@tileshwarnnn590]

Cube casting galat kar raheho tamping roud ko dono hathon se cube ko casted kiya jata hai sir

[@babyanjal1461]

हम घर बनाने का ठेकेदारी करते हैं और आपका सब विडियो देखते हैं आप हिंदी में बात चीत करिए क्योंकि हमको इंग्लिश समझ में नहीं आता हैं।

[@prempande4574]

Weight of cube 8 kg se kam aaye to uska testing consider nhi hota.

[@DeepakKumar-mf9xe]

Sir please share any contact.