GateKeeper is the first roller coaster ride that you see when entering Cedar Point Amusement Park in Sandusky Ohio.  Each person entering the park must walk between the two massive columns that support GateKeeper.  These columns were constructed using up to 50% Slag cement and measure 6’ wide by 20’ deep by 24’ high. They support the tower section of the tallest wing roller coaster in the world.

The massive columns were constructed using monolithic pours so heat of hydration was a major concern.  In addition, the concrete near the bottom of the columns had to gain sufficient strength, during the pour, to support the fluid weight of the concrete above.  To accomplish these two objectives, Slag cement was used in three different mix designs.  Type III cement was used with 25% slag cement for the first 6’ of each column, Type III with 50% slag cement was used from 6’ to 12’ and type I cement with 50% slag cement was used for the last 12 feet of the columns.   To avoid thermal cracking in the massive columns a maximum temperature of 158 F was specified with a maximum temperature differential from interior of concrete to external concrete of 36 F.   The 28-day strength requirement was 4000 psi and the three mix designs achieved an average of 5800 psi. The speed of construction was also of the essence since construction was on a tight timeline in order to have the entire project completed prior to the amusement park reopening in the spring. The use of slag cement for thermal heat control allowed for time and cost savings because cooling pipes were not required to cool the interior of the concrete.

Project credits: Cedar Fair Entertainment Company, Owner; Tony Ravagani Architects, Architect; Bowser-Morner, Inc., Engineer; AA Boos & Sons Inc., Contractor; Elite Concrete Industries, Concrete Supplier; St Marys Cement Inc., Slag Cement Supplier.