A downhole placement tool (216, 516, 716, 1216, 1616) for placing a wellbore material in a wellbore, the downhole placement tool comprising: an actuation assembly (118a, 518a, 1618a); and a placement assembly (118b, 718b, 1218b, 1618b) connected to the actuation assembly; characterized in that: the actuation assembly comprises an actuation housing (226a, 526a, 1626) having a fluid pathway therethrough and an actuation piston (238, 536, 1638) seated in the actuation housing to block the fluid pathway, the actuation piston movable by fluid applied thereto to open the fluid pathway and allow the fluid to pass through the fluid pathway; and the placement assembly comprises: a placement housing (226b, 726b, 1626b) having a pressure chamber (217b, 717b, 1217b, 1617b) to store the wellbore material therein; a door (219, 719, 1219, 1619) positioned in an outlet of the placement housing; and a placement piston (248, 1648) positioned in the placement housing, the placement piston comprising a piston head (264a, 1679a) and a placement rod (264b, 264c, 1664c, 1679c), the piston head slidably movable in the placement housing, the placement rod connected between the piston head and to the door, the piston head movable in response to flow of the fluid from the actuation assembly into the placement assembly to advance the placement piston and open the door whereby the wellbore material is selectively released into the wellbore. an actuation assembly (118a, 518a, 1618a); and a placement assembly (118b, 718b, 1218b, 1618b) connected to the actuation assembly; characterized in that: the actuation assembly comprises an actuation housing (226a, 526a, 1626) having a fluid pathway therethrough and an actuation piston (238, 536, 1638) seated in the actuation housing to block the fluid pathway, the actuation piston movable by fluid applied thereto to open the fluid pathway and allow the fluid to pass through the fluid pathway; and the placement assembly comprises: a placement housing (226b, 726b, 1626b) having a pressure chamber (217b, 717b, 1217b, 1617b) to store the wellbore material therein; a door (219, 719, 1219, 1619) positioned in an outlet of the placement housing; and a placement piston (248, 1648) positioned in the placement housing, the placement piston comprising a piston head (264a, 1679a) and a placement rod (264b, 264c, 1664c, 1679c), the piston head slidably movable in the placement housing, the placement rod connected between the piston head and to the door, the piston head movable in response to flow of the fluid from the actuation assembly into the placement assembly to advance the placement piston and open the door whereby the wellbore material is selectively released into the wellbore. the actuation assembly comprises an actuation housing (226a, 526a, 1626) having a fluid pathway therethrough and an actuation piston (238, 536, 1638) seated in the actuation housing to block the fluid pathway, the actuation piston movable by fluid applied thereto to open the fluid pathway and allow the fluid to pass through the fluid pathway; and the placement assembly comprises: a placement housing (226b, 726b, 1626b) having a pressure chamber (217b, 717b, 1217b, 1617b) to store the wellbore material therein; a door (219, 719, 1219, 1619) positioned in an outlet of the placement housing; and a placement piston (248, 1648) positioned in the placement housing, the placement piston comprising a piston head (264a, 1679a) and a placement rod (264b, 264c, 1664c, 1679c), the piston head slidably movable in the placement housing, the placement rod connected between the piston head and to the door, the piston head movable in response to flow of the fluid from the actuation assembly into the placement assembly to advance the placement piston and open the door whereby the wellbore material is selectively released into the wellbore. a placement housing (226b, 726b, 1626b) having a pressure chamber (217b, 717b, 1217b, 1617b) to store the wellbore material therein; a door (219, 719, 1219, 1619) positioned in an outlet of the placement housing; and a placement piston (248, 1648) positioned in the placement housing, the placement piston comprising a piston head (264a, 1679a) and a placement rod (264b, 264c, 1664c, 1679c), the piston head slidably movable in the placement housing, the placement rod connected between the piston head and to the door, the piston head movable in response to flow of the fluid from the actuation assembly into the placement assembly to advance the placement piston and open the door whereby the wellbore material is selectively released into the wellbore.