The span to depth ratio is in place preliminary as a method of ensuring deflections falls within certain limits. As concrete is a multi-phase material and does not behave linearly, it is often complex to calculate expected accurate deflections. codes set out given span/depth ratios as a simpler method or ensuring deflections remain in given limits. These ratios have been derived empirically from testing.
The compressive strength of concrete as a material does not vary with varying span/depth. However, the amount of the concrete section which is in compression will vary with span and depth due to changes in the applied moment and increase/reduction of the internal lever arm.
no answer
f ′c: concrete compressive strength at 28 days (compression is negative) fcu: concrete crushing strength (compression is negative)
Compressive strength of concrete is defined as the concrete cube of 150 mm x 150 mm x 150 mm with specified proportion with 28 days curing.Target mean strength - In order that not more than the specified proportion of test results are likely to fall below the characteristic strength, the concrete mix has to be designed for a somewhat higher target average compressive strength (fck).__fck = fck + t * swhere ___fck is target average compressive strength at 28 days,fck is a characteristic compressive strength at 28 days ands standard deviationt a statistic, depending upon the accepted proportion of low results and the number of tests.
35N/mm2 actually, the '35' respresents the characteristic design strength of the concrete. this strength is pivotal in design as its the 'lowest fair estimate' of strength.in reality tere is a margin for error (between 5-10MPa)and a 5% defectives built in to a normal probability curve.in my latest research i have found that in some cases the characteristic design strength (in your case 35MPa) can almost be underestimated by 20%.the importance is on-site testing, but as previously stated, if you design to 35MPa... you are definitely on the safe side of concretes inevitable variability
The compressive strength of M25 concrete at 7 days will be between 6-7.5 N/mm2 .
Neither tensile strength nor compressive strength is inherently "stronger." Some materials are stronger in tension; other materials are stronger in compression. For example, rope is much stronger in tension than in compression, but concrete is much stronger in compression than in tension.
tensile strength is approximately between .08 to .15 of compression strength in concrete
f ′c: concrete compressive strength at 28 days (compression is negative) fcu: concrete crushing strength (compression is negative)
The difference in compressive strength is due to the difference between the modulus of elasticity of concrete and that of the steel which is used to apply the compressive force on the concrete. The pressure applies a lateral confinement pressure which is equal to d/3 meaning that for the cylinder, 2d/3 is confined leaving d/3 unconfined whereas for the cylinder 2d/3 is confined means all of the cube is confined. This leads to the cube having a higher compressive strength that the cylinder. For more information, try to read about the triaxial test and the effect of confinement on the compressive strength of soil samples.
Compressive strength of concrete is defined as the concrete cube of 150 mm x 150 mm x 150 mm with specified proportion with 28 days curing.Target mean strength - In order that not more than the specified proportion of test results are likely to fall below the characteristic strength, the concrete mix has to be designed for a somewhat higher target average compressive strength (fck).__fck = fck + t * swhere ___fck is target average compressive strength at 28 days,fck is a characteristic compressive strength at 28 days ands standard deviationt a statistic, depending upon the accepted proportion of low results and the number of tests.
35N/mm2 actually, the '35' respresents the characteristic design strength of the concrete. this strength is pivotal in design as its the 'lowest fair estimate' of strength.in reality tere is a margin for error (between 5-10MPa)and a 5% defectives built in to a normal probability curve.in my latest research i have found that in some cases the characteristic design strength (in your case 35MPa) can almost be underestimated by 20%.the importance is on-site testing, but as previously stated, if you design to 35MPa... you are definitely on the safe side of concretes inevitable variability
The compressive strength of M25 concrete at 7 days will be between 6-7.5 N/mm2 .
The ability to compress is compressive strength but when it acts upon something it becomes latter one
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if water increse stergth will reduce
Neither tensile strength nor compressive strength is inherently "stronger." Some materials are stronger in tension; other materials are stronger in compression. For example, rope is much stronger in tension than in compression, but concrete is much stronger in compression than in tension.
43 grade OPC Cement it denotes the compressive strength of concrete in 43 Mega pascals will attain in 28 days. it is normally used for pavements, Non RCC structures and which are not important for initial strength. where as 53 Grade OPC Cement it denotes the compressive strength of 53 Mega Pascals will attain in concrete with the 28days, and it is used for RCC strengths and which are important to gain initial strength.
The number relates to the compressive strength of a cube of concrete when tested (i.e. 30 N/mm2 or 40N/mm2) The higher the number the greater the strength of the concrete. The choice of concrete grade is usually made at the design stage for the strucutre and effects the overall strength and resistance of the strucutre to decay. You would use a higher strength concrete in a more exposed environment. It is important to use the concrete grade specified for the proposed strucutre.