14 Feb 2019

Concrete and Its Properties

Normal Concrete

Concrete

Concrete is the mixture of Coarse aggregate, Fine aggregate, Water, Cement, Air (entraped) and sometimes admixtures.

Proportions of the Materials

The normal composition of concrete include
  • Cement→ 7% to 15%
  • Aggregate (Fine and Coarse Aggregate)→ 60% to 75%
  • Water→ 14% to 21%
  • Air (entraped)→ 4% to 8%

Properties of Concrete

Compressive Strength 

The uniaxial compressive strength is normally measured by compressive test of a standard cylinder, normally tested after 28 days of curing. Using the testing method of ASTM standard "C31" and 'C39". The compressive strength of concrete is normally represented by strain-stress curve. Which is used to check concrete strength for quality control. The normal rang for standard concrete strength is:

fc'= 3000 psi to fc'= 5000 psi

fc'= Compressive strength
Concrete Compressive Test 

Tensile Strength

This strength normally ranges from 8% to 15% of compressive strength (fc'). The type of test used to determine tensile strength is 
  1. Flexure Test
  2. Split Cylinder Test
Concrete Tensile Test

Relationship b/w Compressive & Tensile Strength

The concrete tensile strength increases with increase in compressive strength. So these both properties are directly proportional to each other:

Tensile Strength ∝ √fc'
Concrete

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