The effect of rate of loading upon the static and fatigue strengths of plain concrete in compression

Synopsis The paper describes an experimental investigation into the effect of the rate of application of steadily increasing loads upon the static strength and of fluctuating loads upon the fatigue strength of plain concretes in compression. Concretes made with gravel, limestone or Lytag aggregate were tested. Increasing the rate of application of load was found, in general, to enhance the static strength andfatigue strength of all three types of concrete. The increase in static strength was found to be greatest in concrete with a relatively weak and soft aggregate such as Lytag and least in a concrete with relatively strong and stiff aggregate such as limestone. In the fatigue tests, a strong correlation was found between the rate of strain increase per cycle during most of the life of a specimen and the endurance of the specimen, irrespective of the rate of application of the load.