Question

1.A concrete cylinder has a measured height of 12.1 in. and a measured circumference of 18.6 in. When tested in unconfined compression, it fails at an axial load of 136,500 lb. What is the unconfined compressive strength of this cylinder?

2.A concrete cylinder has a measured height of 11.9 in. and a measured circumference of 18.7 in. A split cylinder test on this specimen fails at a load of 43,700 lb. What is the tensile strength of this cylinder?

3.A concrete beam specimen has a measured height of 6.01 in., a measured width of 5.75 in., and a length of 20.92 in. It is tested in flexure using beam supports spaced 18.0 in. apart. If the beam fails at an applied load of 4950 lb, what is the modulus of rupture of the specimen?

4.A concrete cylinder has a measured height of 12.0 in. and a measured circumference of 18.8 in. It is to be tested to determine its elastic modulus using a compressometer. According to ASTM, you need to measure the applied load corresponding to a vertical strain of 50 microstrain (i.e., 0.000050 in/in). What measured deflection will be recorded on the dial gage at that point in the test?

5.Assuming a concrete compressive strength of cf= 5420 psi, what load would you apply to the cylinder in Problem 4 to achieve a stress of 0.4cf= 2168 psi?

6.The concrete cylinder in the previous problem supported a measured load of 4500 lb at 50 microstrain and recorded a change in height of 0.0059 in. at a stress of 2168 psi. What is the elastic modulus of the concrete?

Answer 1