Construction Machine

A construction machine including a hydraulic fluid tank for storing a hydraulic fluid, a hydraulic pump for pressurizing the hydraulic fluid of the hydraulic fluid tank, a hydraulic actuator, and a control valve for controlling supply of the hydraulic fluid from the hydraulic pump to the hydraulic actuator and discharge of the hydraulic fluid from the hydraulic actuator to the hydraulic fluid tank, the construction machine comprising:

• an additive tank for storing an additive;
• an additive supply line for supplying the additive from the additive tank to the hydraulic fluid tank;
• an on-off valve disposed on the additive supply line and switchable between a closed state and an open state, for cutting off the supply of the additive from the additive tank to the hydraulic fluid tank in the closed state and supplying the additive from the additive tank to the hydraulic fluid tank in the open state;
• a degree-of-oxidation sensor for sensing a degree to which the hydraulic fluid has been oxidized;
• and
• a controller,
• wherein the controller
• is configured to compute a rate of change in the degree to which the hydraulic fluid has been oxidized, on a basis of a sensed result from the degree-of-oxidation sensor, and perform control for reporting that the on-off valve is to switch into the open state or control for switching the on-off valve into the open state when the rate of change in the degree to which the hydraulic fluid has been oxidized is equal to or higher than a predetermined value, and performs control for reporting that the on-off valve is to switch into the open state or control for switching the on-off valve into the open state when the rate of change in the degree to which the hydraulic fluid has been oxidized is lower than the predetermined value but a machine uptime from a time of replacement of the hydraulic fluid or a machine uptime from a time of switching of the on-off valve from the open state into the closed state is equal to or longer than a predetermined value.