Factors Affecting Concrete Strength

properties of concrete

In addition to Mixing, Pouring and Compaction, the concrete strength mainly depends on the following factors:

Factors Affecting Concrete Strength

(1) Water-Cement Ratio (W/C)

                 To decrease in W/C  will increase the strength of concrete. Normally water-cement ratio is 0.45-0.55 for normal concrete.Affects of W/C on Concrete Strength

(2) Aggregate-Cement Ratio

                    To decrease in Aggregate-Cement Ratio increase the strength of concrete upto numerical value of 2, further decrease of Agg/Cement may cause decrease in strength on concrete.

(3) Aggregate

                    The concrete strength is affected by 

• Aggregate Strength
• Surface Texture
• Grading
• Maximum size of aggregate in concrete

(4) Curing

                 Prolonged moist curing results in getting highest concrete strength.

Rate Of Strength Gain by Concrete

                 The ACI code proposes the rate of strength gain for concrete in which type-I concrete was used at 70F° by the following Equation

  fc’(t)= fc'(28)(t⁄ 4+0.85t) 

In the above Equation t= Time in days fc’= Compressive strength at age “t” in days

Variation in Strength of Concrete

The strength variation of finished concrete depends on

1. Property of concrete component
2. Methods of transportation of concrete
3. Compaction of concrete
4. Discripancies in the test of concrete
5. Compressive Strength of Concrete