Flexural strength of concrete beam, casted, stored and cured under specified conditions.
Test Standard: IS 516:1959
Applications of flexural test:
- Specifying compliance with standards
- It is an essential requirement for concrete mix design
- It is employed in testing concrete for slab and pavement construction
Factors affecting of Flexural Test results:
- Concrete specimen preparation
- Specimen size
- Moisture condition of the concrete specimen
- Curing of the concrete specimen
- And whether the specimen is molded or sawed to the required size
Test appratus :
- Beam moulds of size 150x150x700mm
- Tamping rod of steel 2Kg, 40cm long and ramming face of 25mm square
- Flexural testing machine
Sample Preparation of Concrete
- Determine proportions of materials including cement, sand, aggregate and water.
- Mix the materials using either by hand or using suitable mixing machine in batches with size of 10 percent greater than molding test specimen.
- Measure the slump of each concrete batch after blending.
- Place molds on horizontal surface and lubricate inside surface with proper lubricant material and excessive lubrication should be prevented.
- Pour fresh concrete into the molds in three layers.
- Compact each layer with 16mm rode and apply 25 strokes for each layer or fill the mold completely and compact concrete using vibration table.
- Remove excess concrete from the top of the mold and smoothen it without imposing pressure on it.
- The age of the test is 14 days and 28 days and three specimens for each test should be prepared (according to Indian Code, the specimen is stored in water at 24-30oC for 48hours and then tested)
- Test specimens stored in water at a temperature of 24 to 30 degree Celsius for 48 hours before testing
Test procedure :
|Flexural strength test of concrete|
The flexural strength of the specimen shall be expressed as the modulus of rupture (fb) which if ‘a’ equals the distance between the line of fracture and the nearer support measured on the centre line of the tensile side of the specimen in mm, shall be calculated to the nearest 0.05 N/mm2 as:
fb = (p x l)/(b x d2)
When a is greater than 200mm, or
fb = (3p x a)/ (b x d2)
When ‘a’ is less than 200mm and greater than 170mm, if ‘a’ is less than 170mm, results of the tests shall be discarded.
b = measured width in mm of the specimen, d = measured depth in mm of the specimen at the point of failure, l = length in mm of the span on which the specimen was supported, and p = maximum load in N applied to the specimen.
|Flexural strength test of concrete beam|
Founder & Admin of civilengineeringsolution.com, I am a civil engineer working as a Assistant Engineer (QA/QC).