It is the grade of concrete which indicates the strength of concrete after 28 days curing. M #) means the strength of concrete after 28 days of curing will be 30 N/mm2 .
stress in old concrete
Concretes from grade M-60 to M-80 are called as high strength concretes as per IS 456-2000
In this M refer to Maximum compressive strength and 20 refer that concrete that with stand upto 20KN compressive strength.
Concrete is generally heavier than both sand and gravel. The density of concrete typically ranges from 2,200 to 2,500 kg/m³, while sand has a density of about 1,600 to 2,000 kg/m³ and gravel usually falls between 1,500 to 2,000 kg/m³. Therefore, when comparing equal volumes, concrete will weigh the most.
Concrete is generally heavier than sand. The density of concrete typically ranges from about 2,200 to 2,500 kg/m³, while dry sand has a density of approximately 1,500 kg/m³. Therefore, for the same volume, concrete will weigh significantly more than sand.
The equivalent concrete for M-30 cylinder strength is M-40 cube strength
m-30
1:1:2
Density of M30 and any fresh concrete is 2400kg/cu.m and reinforced concrete density you can take 2500 kg/cu.m
What is mixing ratio for concrete grade 30
30 - 2 = 28 .25 - 2 = 23 .28 * 23 = 644Answer The area covered by grass is 644 square meters
M. D. A. Thomas has written: 'Durability of pfa concrete' -- subject(s): Concrete, Testing, Concrete construction
L. M. James has written: 'Concrete technology' -- subject(s): Concrete
Seven days strength of any concrete usually comes 67% of 28 day strength. So 7 day strength of M30 may be .67*30=20.10 MPa
stress in old concrete
m 35 is the high constituents of concrete
L. M. Poukhonto has written: 'Durability of concrete structures and constructions' -- subject(s): Concrete, Deterioration, Reinforced concrete construction, Testing