So doing a small, lower end, mass concrete pour, the section is a 1.4m x 1.4m x 50m beam with a standard C1 concrete 35Mpa, 280 kg/m3 type 10 cement with 120 kg/m3 slag. Sealed the exposed top, left the forms on and covered the whole thing with insulated tarps for 3 days. Through the weekend...