To evaluate the effect of a certain admixture on the flexure strength of concrete, two mixes were prepared, one without admixture and one with admixture. Three beams were prepared of each mix. All the beams had a cross sectionof 0.15 m by 0.15 m and a span of 0.45 m. The third-point loading flexurestrength test was performed on each beam after 7 days of curing. The loads atfailure of the beams without admixture were 32.8, 34.5, and 31.7 kN, whilethe loads at failure of beams with admixture were 39.4, 35.6, and 35.0 kN.Determine:a. The modulus of rupture of each beam in MPa.b. The average moduli of rupture of the beams without and with admixture.c. The percent of increase of the average modulus of rupture due to addingthe admixture.
To evaluate the effect of a certain admixture on the flexure strength of concrete, two mixes were prepared, one without admixture and one with admixture.
Three beams were prepared of each mix. All the beams had a cross section
of 0.15 m by 0.15 m and a span of 0.45 m. The third-point loading flexure
strength test was performed on each beam after 7 days of curing. The loads at
failure of the beams without admixture were 32.8, 34.5, and 31.7 kN, while
the loads at failure of beams with admixture were 39.4, 35.6, and 35.0 kN.
Determine:
a. The modulus of rupture of each beam in MPa.
b. The average moduli of rupture of the beams without and with admixture.
c. The percent of increase of the average modulus of rupture due to adding
the admixture.
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