A method of controlling a paving process is disclosed. Before inputting a signal current, a precharge operation is performed by flowing a large current. The first pump speed desirably is different from the second pump speed. % of the composition; and at least one acidic stabilizing agent having a pKa ionization constant of from about 1 to about 7. A circulation valve for cementing casing in a well bore, the valve having: a valve housing connected to the casing and comprising a reactive material; a plurality of holes in the housing, wherein the plurality of holes allow fluid communication between an inner diameter of the housing and an exterior of the housing, wherein the reactive material is expandable to close the plurality of holes. According to the invention, at least one play compensating element is arranged circumferentially between two adjacent main bodies, and the play compensating element has circumferentially a higher elasticity than a main body, and the segments are arranged circumferentially without play at room temperature.