13.4. PRSR 07-09-2014 - Laserfiche WebLink

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Mix Design After speaking with our mentor engineers from Cretex,we have recommended that a self- consolidating,high strength concrete mix would be aesthetically and structurally the best choice for the skatepark. Concrete that is self-consolidating can be placed quickly and easily with little vibration,which gives a smooth texture to the exterior. Not only would this be an aesthetically positive choice,but it is also necessary for skaters to have a surface free of bumps and impediments. In addition,the concrete must be high strength,particularly around the ends of skating elements,to resist cracking and flaking due to the repeated impacts where the skaters land. The self-consolidating concrete mix design that was chosen can be found in Appendix D.A small scale test of this mix was performed to assess the usability of the concrete based on aesthetic and strength properties.This was done by us at Cretex Concrete Solutions in Elk River with the guidance of a mentor engineer who specializes in concrete mix design.The test was done by mixing a small batch of the concrete; the mix included water,Type I-II cement, 3/4", #67 rock gravel,washed sand, and three specific admixtures to enhance the mix design including Daravair M Air Entrainer, HRWR plasticizer, and VMAR3 Viscosity Modifier. The concrete mix was then tested for both the air content, and the spread; which resulted in a 6.7% air content and a 24.5 inch spread. Both of these properties indicated a successful concrete mixture to use for a smooth and quickly running concrete. The current mix design may be changed due to cost and the contractor chosen for the project. Skate parks are not unlike basketball courts and tennis courts in that they are highly sensitive and potentially useless when deformations occur.This warrants the use of a contractor that is experienced in skate park design and construction.As previously stated, other work to be done for the site may be subcontracted. However, it is our recommendation that a specialized company be used for the construction of skate park elements.This company will likely have a mix design of their own.As stated previously, there are companies which make precast,modular skatepark elements from concrete. If these elements are purchased, a slightly different concrete mix may be utilized by the 6