Similarly to the indirect tensile strength calculations, the measured and approximate flexural strength calculations are engineering and empirical calculations, respectively. Equation XX3 calculates the flexural strength by calculating the sheer stress at the breaking point while the maximum load is applied. The four point bending test typically overestimates the direct tensile strength by 50 to 100 percent. The approximate flexural strength equation was developed using data from many test specimens. Equation XX4 is only valid with compressive strength units are in MPa.

Only two samples were testes for compressive strength and flexural strength. Therefore a good estimate about the relationship between approximate and measured strength cannot be made. Test sample V had strength in the range of the approximate strength. Sample VIII had a measured strength that was only 17 percent greater than the upper bound of the approximate strength. The limited data collected shows that this approximate relationship works well.

For test sample test sample VII the measured indirect tensile strength was in the range of the approximate strength. Conversely, the measured strength of sample VI was almost twice as much as the upper bound of the approximate strength. Since only two samples were tested there is not enough data to make a strong assessment about the correlation between the measured and approximate indirect tensile strength. The data shows that there is a relationship between the two methods, but the strengths may have a lot of variance as shown in test VI.

Similarly to the indirect tensile strength calculations, the measured and approximate flexural strength calculations are engineering and empirical calculations, respectively. Equation XX3 calculates the flexural strength by calculating the sheer stress at the breaking point while the maximum load is applied. The four point bending test typically overestimates the direct tensile strength by 50 to 100 percent. The approximate flexural strength equation was developed using data from many test specimens. Equation XX4 is only valid with compressive strength units are in MPa.

Only two samples were testes for compressive strength and flexural strength. Therefore a good estimate about the relationship between approximate and measured strength cannot be made. Test sample V had strength in the range of the approximate strength. Sample VIII had a measured strength that was only 17 percent greater than the upper bound of the approximate strength. The limited data collected shows that this approximate relationship works well.

For test sample test sample VII the measured indirect tensile strength was in the range of the approximate strength. Conversely, the measured strength of sample VI was almost twice as much as the upper bound of the approximate strength. Since only two samples were tested there is not enough data to make a strong assessment about the correlation between the measured and approximate indirect tensile strength. The data shows that there is a relationship between the two methods, but the strengths may have a lot of variance as shown in test VI.

Similarly to the indirect tensile strength calculations, the measured and approximate flexural strength calculations are engineering and empirical calculations, respectively. Equation XX3 calculates the flexural strength by calculating the sheer stress at the