A concrete flow leakage-preventing shut-off valve mounted on a concrete delivery hose, whereby a flow of concrete is controlled between an open concrete flow condition and a closed concrete flow condition, the valve comprising: an outer flexible fabric casing configured to be disposed around the concrete delivery hose, the outer flexible fabric casing having opposite first and second casing ends (16a, 16b) lying adjacent and spaced from each other; a flexible inflatable bladder disposed within the outer flexible fabric casing along an inner surface thereof, the flexible bladder defining a gas chamber therein, and having opposite first and second bladder ends (18a, 18b) lying adjacent and spaced from one another and inside the opposite first and second casing ends (16a, 16b), the concrete delivery hose passing through the outer flexible fabric casing and the flexible bladder and isolating the concrete flow from the outer flexible fabric casing and the flexible bladder; a gas intake/exhaust device extending through the outer flexible fabric casing and into the gas chamber such that pressurized gas is introduced into the gas chamber causing the flexible bladder to be forced radially inward to constrict and close upon the concrete delivery hose to define the closed concrete flow condition wherein concrete flow from an outlet end of the concrete delivery hose is terminated, and whereby pressurized gas is exhausted from the gas chamber for quickly exhausting gas delivered to the gas intake/exhaust device to define the open concrete flow condition, wherein concrete flow from the outlet end of the concrete delivery hose is permitted; and a clamping arrangement securing the opposite first and second casing ends (16a, 16b) and the opposite first and second bladder ends (18a, 18b) together in radially and axially spaced apart relationship relative thereto, the clamping arrangement being configured to maintain a surrounding relationship of the outer flexible fabric casing and the flexible bladder with respect to the concrete delivery hose. an outer flexible fabric casing configured to be disposed around the concrete delivery hose, the outer flexible fabric casing having opposite first and second casing ends (16a, 16b) lying adjacent and spaced from each other; a flexible inflatable bladder disposed within the outer flexible fabric casing along an inner surface thereof, the flexible bladder defining a gas chamber therein, and having opposite first and second bladder ends (18a, 18b) lying adjacent and spaced from one another and inside the opposite first and second casing ends (16a, 16b), the concrete delivery hose passing through the outer flexible fabric casing and the flexible bladder and isolating the concrete flow from the outer flexible fabric casing and the flexible bladder; a gas intake/exhaust device extending through the outer flexible fabric casing and into the gas chamber such that pressurized gas is introduced into the gas chamber causing the flexible bladder to be forced radially inward to constrict and close upon the concrete delivery hose to define the closed concrete flow condition wherein concrete flow from an outlet end of the concrete delivery hose is terminated, and whereby pressurized gas is exhausted from the gas chamber for quickly exhausting gas delivered to the gas intake/exhaust device to define the open concrete flow condition, wherein concrete flow from the outlet end of the concrete delivery hose is permitted; and a clamping arrangement securing the opposite first and second casing ends (16a, 16b) and the opposite first and second bladder ends (18a, 18b) together in radially and axially spaced apart relationship relative thereto, the clamping arrangement being configured to maintain a surrounding relationship of the outer flexible fabric casing and the flexible bladder with respect to the concrete delivery hose.