What is the weight of a cubic meter of concrete?

mass = density * volume

weight = mass * acceleration due to gravity

W = (2400 kg/m^3)*(1 m^3)*(9.8 m/s^2) = 23520 Newtons

convert to pounds

23520 Newtons = 5287.5 lbs

(note 1 lb is approximately 4.448 Newtons)