Figure 8 . Flexural strength of different concrete mixes
Figure 9 . Relationship between compressive strength and flexural strength of concrete mixes
Flexural Strength Flexural strength based on curing periods of control and coal concretes are shown in Figure 8 . The flexural strength values at the age of 28 days are 5.24MPa and 5.8 MPa for control and coal concrete , respectively . Coal concrete has a 21 % higher flexural strength than control concrete . This is due to the higher percentage of filler compared with control concrete which increases the bonding between the aggregates and cement . As such , this makes coal concrete stronger compared with control concrete . Moreover , flexural strength is directly proportional to the pozzolanic reaction and hydration reaction of cement .
As illustrated in Figure 9 , both compressive and flexural strengths have a positive and strong linear relationship . A perfect estimation of the correlation was depicted by the determination of the R 2 coefficient value of 99 % and 91 %. The relationship was established for the compressive
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