Answer:
E = 94,5048 lb/ft^2
Step-by-step explanation:
Given:
- The density of the concrete specimen W = 135 lb/ft^3
- The 28-day compression strength of S = 4,000 psi
Find:
Calculate the Young’s modulus of a concrete specimen
Briefly discuss how the Young’s modulus (modulus of elasticity) of concrete is determined
Solution:
- ACI Committee 318 recommends the following empirical relationship between Young’s modulus and compressive strength of normal strength concrete:
E = 33*W^1.5*sqrt(S)
- Plug in the values:
E = 33*(135)^1.5*sqrt(4,000/12)
E = 94,5048 lb/ft^2
- Piezoelectric materials can be used as both sensors and actuators. One piezoelectric acts as an actuator and sends high frequency stress waves through a concrete test cylinder. A second piezoelectric, acting as a sensor, then picks up a signal due to the propagated stress waves at the opposite end of the cylinder. Based on a relation with the speed of sound in an elastic solid, an approximation of the Young’s modulus, E, can be
made from the equation shown below:
E = V^2 ( ( 1 + v)(1-2v)*W) / ( 1 - v))
Where,
V: Speed of sound
v: poisson ratio
W: Density of concrete