what is compressive strength of concrete?

Question

i have a lab report to submit on monday a.m. it's incomplete help find the definition of compressive strength of concrete and the factors affecting it.

Answer 1

Concrete is a structural material which consists of Portland cement, aggregate (sand and rock), and water (to make the chemical reaction called hydration occur.) Concrete can sometimes contain other substances, such as fly ash from industrial smoke stacks, which can change its properties.
Concrete is a very strong material when it is placed in compression. It is, however, extremely weak in tension. It is for this reason that we use reinforcement in concrete structures. The reinforcement, which is usually steel, takes up the slack for the weakness of the concrete in tension.
There are many ways to test the strength of a batch of concrete. The tests used can be categorized as destructive and nondestructive tests. Usually when a batch of concrete is ordered on a job site it is specified to be of a specific compressive strength -- 4000 psi, for instance. When the concrete comes to the job site in a ready-mix truck, the contractor places some of the batch in cylinders which are 6 inches in diameter and 12 inches in height. These cylinders are cured for 28 days and tested by compression until they are crushed. This will give the contractor or the engineer the compressive strength for that batch of concrete. He or she can then compare that value to the design value used to make sure that the structure was constructed properly.
Once the concrete has been placed for a particular structure, there is a nondestructive test which can be performed to estimate the strength of the concrete. This method uses a Schmidt hammer (also called a Swiss hammer). This method of testing is based on the inertia of a ball inside the Schmidt hammer testing apparatus that is "bounced off" of the concrete.

Answer 2

Compressive Strength Definition

Answer 3

The strength of concrete is determined using small specimens like 6 X 12 in. cylinders. The test cylinders are cast in steel mould in three layers, each layer being compacted by 25 strokes of a steel rod. The moulded specimens are stored at specified time and condition until the prescribed age of testing, usually 28 days. The compressive strength of the cylinder is the maximum uniaxial load recorded divided by the cross sectional area of the cylinder when tested using hydraulically operated compression machines. The cylinders give the potential strength of the concrete.

The compressive strength is influenced by the curing conditions, specimen preparation, age at testing, mode of testing, and mode of failure of the specimen.

Answer 4

Compressive strength or compression strength is the capacity of a material or structure to withstand loads tending to reduce size, as opposed to tensile strength, which withstands loads tending to elongate. In other words, compressive strength resists compression (being pushed together), whereas tensile strength resists tension (being pulled apart). In the study of strength of materials, tensile strength, compressive strength, and shear strength can be analyzed independently.

Answer 5

The strength which can resist from the compression is called compressive strength.
Concrete is good in compressive strength....so we use concrete.

Answer 6

Factors affecting strength:

Water-to-cement ratio.

Amount of air entrainment.

Shape of the rock.

Sieve analysis.

Quality of the rock and sand

Accelerators or retarders used.

Answer 7

See http://www.nrmca.org/aboutconcrete/cips/35p.pdf